High-flatness environment-friendly plastic woven tube cloth and preparation method thereof

Abstract

The invention provides high-flatness environment-friendly plastic woven tube cloth and a preparation method thereof, and relates to the technical field of plastic woven tube cloth. The high-flatness environment-friendly plastic woven tube cloth comprises a plastic woven tube cloth substrate, a one-way stress constraint layer and an elastic buffer transfer layer, the plastic woven tube cloth base is formed by interweaving regenerated PP flat filaments in a plain weave mode, the warp density is 10-12 pieces per inch, the weft density is 8-10 pieces per inch, and the monofilament thickness deviation is smaller than or equal to 3%; the unidirectional stress constraint layer is prepared from the following components in percentage by mass: 50%-55% of semi-crystalline PP resin, 25%-30% of directionally-arranged flaky nano talcum powder, 8%-10% of an anchoring type compatilizer, 3%-5% of a unidirectional constraint aid, 3%-5% of nano calcium carbonate and 0.5%-1% of an antioxidant 1010; the one-way constraint auxiliary agent is erucyl amide. And the elastic buffer layer disperses loads, no fracture layering exists under the large loads, the full-PP-based material can be recycled, and the requirements for environmental protection and high-end application are met.

Description

Technical Field

[0001] This invention relates to the field of woven plastic tubular fabric technology, specifically to a high-flatness environmentally friendly woven plastic tubular fabric and its preparation method. Background Technology

[0002] Woven plastic tubing, a commonly used packaging material, is widely used in agriculture, industry, construction, and other fields due to its lightweight, high strength, and low cost. With increasingly stringent environmental requirements, the use of recycled plastic raw materials to produce woven plastic tubing has become an industry trend. However, the performance fluctuations of recycled raw materials can easily lead to uneven stress distribution during the weaving process, resulting in surface unevenness. Furthermore, in high-end applications such as grain storage and chemical raw material packaging, higher requirements are placed on the flatness of woven plastic tubing. Defects commonly found in traditional woven plastic tubing, such as wavy edges, raised interlacing points, and excessive flatness tolerances, seriously affect the sealing performance and appearance consistency of the packaging.

[0003] In existing technologies, methods to improve the flatness of woven plastic tubular fabrics mostly focus on optimizing weaving tension or adding a single heat-setting process. For example, adjusting the collective tension control parameters of the warp yarns can reduce the difference in warp yarn tension; or using a single-roller heat-setting process can alleviate the internal stress of the weaving. However, the above methods have significant limitations: collective tension control is difficult to achieve precise matching of the tension of individual warp yarns, and local unevenness is still likely to occur; a single heat-setting process can only temporarily eliminate some internal stress, and during subsequent use, the residual internal stress is easily released due to changes in temperature and humidity or the influence of load, leading to warping and deformation of the tubular fabric.

[0004] To further improve flatness, some solutions introduce coating processes. However, existing coatings are mostly single, rigid systems, which are incompatible with the high-toughness mechanical properties of recycled woven tubular fabric. When bearing heavy loads, rigid coating layers are prone to cracking or even peeling, compromising reliability. Furthermore, existing coating processes do not consider the directional constraint of stress, making it difficult to fundamentally suppress internal stress rebound, resulting in insufficient flatness stability. In addition, some coatings use non-environmentally friendly components, conflicting with the environmentally friendly positioning of recycled woven tubular fabric and limiting the product's widespread application.

[0005] Therefore, developing a plastic woven tubular fabric that combines high flatness, environmental friendliness, and mechanical reliability, and solving the problems of internal stress rebound and coating layer cracking through the synergistic design of directional stress constraint and elastic buffer, has become a technical bottleneck that the industry urgently needs to overcome. Summary of the Invention

[0006] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a high-flatness environmentally friendly woven plastic tubular fabric and its preparation method, which solves the problems of poor flatness, easy rebound and warping due to internal stress, easy cracking of rigid coating under load, and insufficient environmental protection of traditional woven plastic tubular fabric.

[0007] Technical solution To achieve the above objectives, the present invention is implemented through the following technical solution: a high-flatness environmentally friendly woven plastic tubular fabric, which, from the inside out, includes a woven plastic tubular fabric base, a unidirectional stress constraint layer, and an elastic buffer transfer layer; The woven tubular fabric base is made of recycled PP flat yarns woven in a plain weave, with a warp density of 10-12 yarns / inch, a weft density of 8-10 yarns / inch, and a single filament thickness deviation of ≤3%. The unidirectional stress constraint layer is composed of the following components in the indicated mass percentages: 50%–55% semi-crystalline PP resin, 25%–30% oriented sheet-like nano-talc powder, 8%–10% anchoring compatibilizer, 3%–5% unidirectional constraint aid, 3%–5% nano-calcium carbonate, and 0.5%–1% antioxidant 1010; the oriented sheet-like nano-talc powder has a particle size ≤1μm, an aspect ratio ≥50, and its surface is treated with a coupling agent, and it is arranged parallel to the surface of the woven fabric substrate; the anchoring compatibilizer is maleic anhydride-grafted PP with a grafting rate of 1.5%; the unidirectional constraint aid is erucamide. The elastic buffer transfer layer is composed of the following components in the indicated mass percentages: environmentally friendly TPE 70%–75%, recycled PP resin 10%–15%, wear-resistant filler 8%–10%, toughening agent 3%–5%, UV stabilizer UV-531 0.5%–1%, and antioxidant 168 0.5%–1%. The environmentally friendly TPE is PP-based, with a Shore A hardness of 60–70 and an elongation at break ≥300%. The wear-resistant filler is ultrafine talc powder with a particle size ≤2μm. The toughening agent is EVA resin with a VA content of 18%. The flatness tolerance of this high-flatness environmentally friendly plastic woven tubular fabric is ≤0.08mm / m. After being subjected to a large load cycle of 80% of its own breaking strength for 100 cycles, the elastic buffer transmission layer has no cracks or breaks, and there is no delamination at the interface of each layer. After high and low temperature cycles (-20℃~60℃, 50 cycles), the flatness change rate is ≤0.02%.

[0008] Preferably, the thickness of the uniaxial stress constraint layer is 0.03 to 0.04 mm, and the thickness of the elastic buffer transfer layer is 0.05 to 0.08 mm.

[0009] Preferably, the semi-crystalline PP resin has a melt index of 3.0 g / 10 min and a crystallinity of 55%; the recycled PP resin has a melt index of 3.2 g / 10 min.

[0010] A method for preparing a high-flatness, environmentally friendly woven plastic tubular fabric includes the following steps: S1. Preparation of woven tubular fabric base: Recycled PP granules are extruded and stretched online to prepare recycled PP flat yarns. The extrusion temperatures are 165℃ in zone 1, 175℃ in zone 2, and 180℃ in zone 3, with a stretch ratio of 3.5~4.0 times. After stretching, the yarns are heat-set in an oven at 80~85℃ for 10~15s. The recycled PP flat yarns are then woven into raw tubular fabrics using a circular loom with independent tension control on each spindle. The warp tension is 8~10N, the tension deviation of a single spindle is ≤0.5N, and the weft weaving tension is 6~8N. The raw tubular fabrics are then heat-set using a double roller. The upper roller temperature is 110~115℃, the lower roller temperature is 105~110℃, the tubular fabric travel speed is 8~10m / min, the heat-setting time is 20~30s, and then the fabrics are cooled at room temperature for 30s. S2. Substrate pretreatment: Plasma treatment is performed on the woven plastic tubular substrate cooled in step S1, with a power of 100-150W and a treatment time of 5-10s, so that the surface energy of the substrate is ≥40mN / m. S3. Uniaxial stress constraint layer coating: A uniaxial stress constraint layer is coated on the surface of the pretreated plastic woven tubular fabric substrate using a scraper coating method. The angle between the scraper and the surface of the tubular fabric is 15°~20°. The coating temperature is 80~85℃. After that, it is cured by gradient cooling. First, it is cooled to 40℃ at a rate of 20℃ / min, and then it is naturally cooled to room temperature. S4. Coating of elastic buffer transfer layer: The elastic buffer transfer layer is coated on the surface of the unidirectional stress constraint layer by roller coating. The coating thickness is 0.05-0.08mm. Then it is cured by hot air at 60-65℃ for 15-20s and then cooled at 25℃ for 10s. S5. Finished product winding: The tubular fabric treated in step S4 is wound up under constant tension, with a winding tension of 5-8N and a roundness deviation of the winding roller ≤0.05mm, to obtain a high-flatness environmentally friendly woven tubular fabric finished product.

[0011] Preferably, the specifications of the recycled PP flat yarn in step S1 are a width of 1.8±0.1mm and a thickness of 0.12±0.01mm; the shuttle track of the circular loom has a processing accuracy Ra≤0.4μm, a track roundness deviation≤0.1mm, and is equipped with 8 to 12 evenly distributed guide wheels.

[0012] Preferably, the coating thickness of the unidirectional stress constraint layer in step S3 is 0.03 to 0.04 mm; the roller coating speed in step S4 is synchronized with the travel speed of the bobbin in step S1.

[0013] Beneficial effects This invention provides a high-flatness, environmentally friendly woven plastic tubular fabric and its preparation method. It has the following beneficial effects: 1. This invention provides a high-flatness environmentally friendly woven plastic tubular fabric and its preparation method. This invention utilizes a directional filler arrangement of a unidirectional stress constraint layer and a gradient curing process to precisely fill the interlacing gaps and surface unevenness of the woven plastic tubular fabric substrate. Combined with the smoothing coverage of an elastic buffer transfer layer, the flatness tolerance of the finished product is controlled below 0.08 mm / m. The reverse locking function of the unidirectional stress constraint layer completely suppresses internal stress rebound. After high and low temperature cycling, the flatness change rate is ≤0.02%, significantly superior to products prepared by traditional processes, effectively meeting the requirements of high-end packaging scenarios for sealing and appearance consistency.

[0014] 2. This invention provides a high-flatness environmentally friendly woven plastic tubular fabric and its preparation method. The invention employs a composite structure design of an elastic buffer transfer layer and a unidirectional stress constraint layer. The high elasticity of the elastic buffer transfer layer can evenly distribute external loads across the entire surface of the tubular fabric, avoiding localized stress concentration. The unidirectional stress constraint layer, through interface anchoring design, achieves efficient transmission of external forces and directional locking of internal stress, enabling the coating layer and the woven plastic tubular fabric substrate to form a collaborative load-bearing system. Verified by large-load cyclic testing, after 100 cycles of a load equal to 80% of its own breaking strength, the elastic buffer transfer layer showed no cracks or breaks, and there was no delamination at the interfaces between layers. The service life is more than 5 times longer than products using traditional coating processes. Detailed Implementation

[0015] 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.

[0016] Example 1 1. Raw material preparation Woven tubular fabric base material: recycled PP granules (melt index 3.2g / 10min), with 12% biodegradable compatibilizer (maleic anhydride grafted PP, grafting rate 1.5%) added. Raw materials for the unidirectional stress constraint layer (by mass): 52% semi-crystalline PP resin (melt index 3.0 g / 10 min, crystallinity 55%), 28% oriented sheet-like nano-talc powder (particle size 0.8 μm, aspect ratio 60, surface treated with silane coupling agent), 9% anchoring compatibilizer (maleic anhydride grafted PP, grafting rate 1.5%), 4% unidirectional constraint aid (erucamide), 5% nano-calcium carbonate (particle size 40 nm), and 2% antioxidant 1010. Elastic buffer transfer layer raw materials (by mass): environmentally friendly TPE (PP-based, Shore A 65, elongation at break 320%) 72%, recycled PP resin (melt index 3.2g / 10min) 12%, wear-resistant filler (ultrafine talc powder, particle size 1.5μm) 9%, toughening agent (EVA resin, VA content 18%) 4%, UV stabilizer UV-531 1%, antioxidant 168 2%.

[0017] 2. Preparation method S1. Preparation of woven plastic tubular fabric base: Recycled PP granules were uniformly mixed with a biodegradable compatibilizer and then extruded and granulated using a two-stage extruder. The extrusion temperatures were 165℃ in zone one, 175℃ in zone two, and 180℃ in zone three, with the temperature difference controlled within 3℃. After granulation, recycled PP flat yarns were prepared using an online stretching and shaping process with a stretching ratio of 3.8 times. After stretching, the yarns were immediately placed in a heat-setting oven at 82℃ and held for 12 seconds. The specifications of the prepared recycled PP flat yarns were 1.8±0.1mm in width, 0.12±0.01mm in thickness, and a single filament thickness deviation of 2.5%.

[0018] The recycled PP flat yarns are fed into a circular loom and woven into a green tube fabric using a single-spindle independent tension control method. The warp tension is 9N, the single-spindle tension deviation is 0.3N, and the warp yarns are arranged in a layered arrangement with equally spaced reed teeth, with a reed tooth spacing of 1.8±0.1mm. The weft yarn weaving tension is 7N. The circular loom shuttle track processing accuracy Ra=0.3μm, the track roundness deviation is 0.08mm, and it is equipped with 10 evenly distributed guide wheels with a shuttle running speed deviation of 3%.

[0019] The raw tubular fabric enters the double-roller heat setting device. The temperature of the upper roller is 112℃ and the temperature of the lower roller is 108℃, with a temperature difference of 4℃. The tubular fabric travels at a speed of 9m / min and the heat setting time is 25s. After heat setting, it enters a room temperature cooling rack for 30s to obtain the woven plastic tubular fabric base. The warp density is tested to be 11 threads / inch and the weft density is 9 threads / inch.

[0020] S2. Substrate pretreatment: The cooled woven plastic tubular fabric substrate was subjected to plasma treatment with a power of 120W and a treatment time of 8s. After treatment, the surface strength of the substrate reached 42mN / m.

[0021] S3. Uniaxial stress confinement layer coating: The raw materials for the uniaxial stress constraint layer are mixed evenly and then heated to 83°C in a melting kettle to form a homogeneous system. The uniaxial stress constraint layer is then coated onto the surface of the pretreated woven tubular fabric substrate using a scraper coating method. The angle between the scraper and the surface of the tubular fabric is 18°, and the coating thickness is 0.035mm. After coating, the substrate is subjected to gradient cooling and curing. It is first cooled to 40°C at a rate of 20°C / min, and then naturally cooled to room temperature to obtain the tubular fabric intermediate covered with the uniaxial stress constraint layer.

[0022] S4. Elastic buffer transfer layer coating: Mix all the raw materials of the elastic buffer transfer layer evenly, put them into a melting kettle and heat them to 63°C to melt them into a homogeneous system; use a roller coating method to coat the surface of the unidirectional stress constraint layer with an elastic buffer transfer layer, the coating thickness is 0.06mm, the roller coating speed is synchronized with the travel speed of the tubular fabric (9m / min); after coating, put it into a hot air curing box at 63°C for 18s to cure, and then cool it at 25°C for 10s.

[0023] S5. Finished product rewinding: The cooled tubular fabric is wound up under constant tension of 6.5N and the roundness deviation of the winding roller is 0.04mm. After winding, a high-flatness environmentally friendly woven tubular fabric is obtained.

[0024] 3. Performance Testing The performance of the finished product prepared in Example 1 was tested. The testing methods and results are as follows: Flatness inspection: A laser flatness detector was used, and the flatness was inspected every 10m, with each inspection length being 1m, for a total of 10 points. The average flatness tolerance was 0.06mm / m. High and low temperature cycling stability test: The sample was placed in a high and low temperature test chamber and subjected to a high and low temperature cycling test from -20℃ to 60℃. After 50 cycles, the flatness tolerance was measured to be 0.061 mm / m, and the flatness change rate was 0.017%. High load cyclic bearing test: A ring tensile test was adopted, and the maximum load applied was 80% of the sample's fracture strength. After 100 cycles, visual and microscopic observation showed that the elastic buffer transfer layer had no cracks or breaks. There was no delamination at the interfaces between the uniaxial stress constraint layer and the woven fabric substrate, and between the elastic buffer transfer layer and the uniaxial stress constraint layer. The bonding strength between the coating layer and the woven fabric was tested to be 9.5 N / 10 mm. Environmental performance testing: The sample is made entirely of PP-based material, which is fully recyclable, and no harmful volatile organic compounds were detected (VOC content ≤ 5 mg / m³). 3 It complies with the requirements of GB / T 38082-2019 "General Rules for Recycled Plastics".

[0025] Comparative Example 1 (Traditional heat setting process) The same woven tubular fabric base material and preparation parameters as in Example 1 were used, but the unidirectional stress constraint layer and elastic buffer transfer layer were not coated. The tubular fabric was only heat-set with double rollers before being wound up. Performance testing of the finished product showed the following results: flatness tolerance 0.52 mm / m; after 50 high and low temperature cycles, the flatness tolerance was 0.85 mm / m, with a flatness change rate of 63.5%; after 30 cycles of a load equal to 80% of its own breaking strength, the tubular fabric exhibited obvious wavy edges and warping.

[0026] Comparative Example 2 (Single Rigid Coating Process) Using the same woven plastic tubular substrate material and preparation parameters as in Example 1, a traditional rigid PP coating (without unidirectional stress constraint design and elastic buffer layer) was applied only to the substrate surface, with a coating thickness of 0.095 mm. Performance testing of the finished product showed the following results: flatness tolerance 0.15 mm / m; after 50 high and low temperature cycles, the flatness tolerance was 0.28 mm / m, with a flatness change rate of 86.7%; after 20 cycles of a load representing 80% of its own fracture strength, multiple cracks appeared in the rigid coating layer; after 50 cycles, the coating layer peeled off over a large area, with a bonding strength of only 5.2 N / 10 mm.

[0027] The comparison of the test results of Example 1 with those of Comparative Examples 1 and 2 shows that the present invention, through the composite structure design of a unidirectional stress constraint layer and an elastic buffer transfer layer, combined with a precise manufacturing process, can significantly improve the flatness and dimensional stability of woven plastic tubular fabric, while strengthening the mechanical synergy and matching, effectively solving the problems of internal stress rebound and coating cracking that exist in traditional processes, and also has excellent environmental performance.

[0028] Example 2 The difference from Example 1 is as follows: The raw material composition of the uniaxial stress constraint layer is as follows: 55% semi-crystalline PP resin, 25% oriented sheet-like nano talc powder, 8% anchoring compatibilizer, 5% uniaxial constraint aid, 4% nano calcium carbonate, and 3% antioxidant 1010; the oriented sheet-like nano talc powder has a particle size of 1μm and an aspect ratio of 50. The raw material composition of the elastic buffer transfer layer is as follows: environmentally friendly TPE 75%, recycled PP resin 10%, wear-resistant filler 8%, toughening agent 3%, UV stabilizer UV-531 2%, and antioxidant 168 2%; the environmentally friendly TPE has a Shore A hardness of 70 and an elongation at break of 300%. Preparation process parameters: Double roller heat setting, upper roller temperature 115℃, lower roller temperature 110℃; unidirectional stress constraint layer coating temperature 85℃, coating thickness 0.04mm; elastic buffer transfer layer coating thickness 0.08mm; hot air curing temperature 65℃, curing time 20s.

[0029] The performance of the finished product prepared in Example 2 was tested, and the results were as follows: the flatness tolerance was 0.07 mm / m, the flatness change rate after 50 high and low temperature cycles was 0.019%; after 100 heavy load cycles, the coating showed no cracking or delamination, the bonding strength was 9.2 N / 10 mm, and the environmental performance met the requirements.

[0030] Example 3 The difference from Example 1 is as follows: The raw material composition of the uniaxial stress constraint layer is as follows: 50% semi-crystalline PP resin, 30% oriented sheet-like nano talc powder, 10% anchoring compatibilizer, 3% uniaxial constraint aid, 5% nano calcium carbonate, and 2% antioxidant 1010; the oriented sheet-like nano talc powder has a particle size of 0.6μm and an aspect ratio of 70. The raw material composition of the elastic buffer transfer layer is as follows: environmentally friendly TPE 70%, recycled PP resin 15%, wear-resistant filler 10%, toughening agent 3%, UV stabilizer UV-531 1%, and antioxidant 168 1%; the environmentally friendly TPE has a Shore A hardness of 60 and an elongation at break of 350%. Preparation process parameters: Double roller heat setting, upper roller temperature 110℃, lower roller temperature 105℃; unidirectional stress constraint layer coating temperature 80℃, coating thickness 0.03mm; elastic buffer transfer layer coating thickness 0.05mm; hot air curing temperature 60℃, curing time 15s.

[0031] The performance of the finished product prepared in Example 3 was tested, and the results were as follows: the flatness tolerance was 0.08 mm / m, the flatness change rate was 0.02% after 50 cycles of high and low temperature; the coating showed no cracking or delamination after 100 cycles of heavy load, the bonding strength was 9.0 N / 10 mm, and the environmental performance met the requirements.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-flatness, environmentally friendly woven plastic tubular fabric, characterized in that, From the inside out, it consists of a woven plastic tubular fabric base, a unidirectional stress constraint layer, and an elastic buffer transfer layer. The woven tubular fabric base is made of recycled PP flat yarns woven in a plain weave, with a warp density of 10-12 yarns / inch, a weft density of 8-10 yarns / inch, and a single filament thickness deviation of ≤3%. The unidirectional stress constraint layer is composed of the following components in the indicated mass percentages: 50%–55% semi-crystalline PP resin, 25%–30% oriented sheet-like nano-talc powder, 8%–10% anchoring compatibilizer, 3%–5% unidirectional constraint aid, 3%–5% nano-calcium carbonate, and 0.5%–1% antioxidant 1010; the oriented sheet-like nano-talc powder has a particle size ≤1μm, an aspect ratio ≥50, and its surface is treated with a coupling agent, and it is arranged parallel to the surface of the woven fabric substrate; the anchoring compatibilizer is maleic anhydride-grafted PP with a grafting rate of 1.5%; the unidirectional constraint aid is erucamide. The elastic buffer transfer layer is composed of the following components in the indicated mass percentages: environmentally friendly TPE 70%–75%, recycled PP resin 10%–15%, wear-resistant filler 8%–10%, toughening agent 3%–5%, UV stabilizer UV-531 0.5%–1%, and antioxidant 168 0.5%–1%. The environmentally friendly TPE is PP-based, with a Shore A hardness of 60–70 and an elongation at break ≥300%. The wear-resistant filler is ultrafine talc powder with a particle size ≤2μm. The toughening agent is EVA resin with a VA content of 18%. The flatness tolerance of this high-flatness environmentally friendly plastic woven tubular fabric is ≤0.08mm / m. After being subjected to a large load cycle of 80% of its own breaking strength for 100 cycles, the elastic buffer transmission layer has no cracks or breaks, and there is no delamination at the interface of each layer. After high and low temperature cycles (-20℃~60℃, 50 cycles), the flatness change rate is ≤0.02%.

2. The high-flatness environmentally friendly woven tubular fabric according to claim 1, characterized in that, The thickness of the uniaxial stress constraint layer is 0.03–0.04 mm, and the thickness of the elastic buffer transfer layer is 0.05–0.08 mm.

3. The high-flatness environmentally friendly woven tubular fabric according to claim 1, characterized in that, The semi-crystalline PP resin has a melt index of 3.0 g / 10 min and a crystallinity of 55%; the recycled PP resin has a melt index of 3.2 g / 10 min.

4. A method for preparing a high-flatness environmentally friendly woven plastic tubular fabric, characterized in that, Includes the following steps: S1. Preparation of woven tubular fabric base: Recycled PP granules are extruded and stretched online to prepare recycled PP flat yarns. The extrusion temperatures are 165℃ in zone 1, 175℃ in zone 2, and 180℃ in zone 3, with a stretch ratio of 3.5~4.0 times. After stretching, the yarns are heat-set in an oven at 80~85℃ for 10~15s. The recycled PP flat yarns are then woven into raw tubular fabrics using a circular loom with independent tension control on each spindle. The warp tension is 8~10N, the tension deviation of a single spindle is ≤0.5N, and the weft weaving tension is 6~8N. The raw tubular fabrics are then heat-set using a double roller. The upper roller temperature is 110~115℃, the lower roller temperature is 105~110℃, the tubular fabric travel speed is 8~10m / min, the heat-setting time is 20~30s, and then the fabrics are cooled at room temperature for 30s. S2. Substrate pretreatment: Plasma treatment is performed on the woven plastic tubular substrate cooled in step S1, with a power of 100-150W and a treatment time of 5-10s, so that the surface energy of the substrate is ≥40mN / m. S3. Uniaxial stress constraint layer coating: A uniaxial stress constraint layer is coated on the surface of the pretreated plastic woven tubular fabric substrate using a scraper coating method. The angle between the scraper and the surface of the tubular fabric is 15°~20°. The coating temperature is 80~85℃. After that, it is cured by gradient cooling. First, it is cooled to 40℃ at a rate of 20℃ / min, and then it is naturally cooled to room temperature. S4. Coating of elastic buffer transfer layer: The elastic buffer transfer layer is coated on the surface of the unidirectional stress constraint layer by roller coating. The coating thickness is 0.05-0.08mm. Then it is cured by hot air at 60-65℃ for 15-20s and then cooled at 25℃ for 10s. S5. Finished product winding: The tubular fabric treated in step S4 is wound up under constant tension, with a winding tension of 5-8N and a roundness deviation of the winding roller ≤0.05mm, to obtain a high-flatness environmentally friendly woven tubular fabric finished product.

5. The preparation method according to claim 4, characterized in that, The specifications of the recycled PP flat yarn in step S1 are a width of 1.8±0.1mm and a thickness of 0.12±0.01mm; the shuttle track of the circular loom has a processing accuracy Ra≤0.4μm, a track roundness deviation≤0.1mm, and is equipped with 8 to 12 evenly distributed guide wheels.

6. The preparation method according to claim 4, characterized in that, In step S3, the coating thickness of the uniaxial stress constraint layer is 0.03 to 0.04 mm; in step S4, the roller coating speed is synchronized with the travel speed of the bobbin in step S1.