High-toughness anti-falling plastic woven bag and preparation method thereof

Abstract

The invention relates to a high-toughness anti-falling plastic woven bag and a preparation method thereof. The high-toughness anti-falling plastic woven bag comprises 85-100 parts of polypropylene, 3-5 parts of polyethylene and 5-10 parts of filler, the filling material contains 10%-15% of LDPE and can induce beta-shaped crystallization, the filling material capable of inducing the beta-shaped crystallization is selected, and the polypropylene beta crystal has a loose spherocrystal structure, so that the elongation of the flat filament can be improved within a certain range; meanwhile, polypropylene and polyethylene are blended and have similar polarity and better thermodynamic compatibility, so that the melting viscosity is increased, the flat filaments are effectively prevented from fuzzing and splitting, and the toughness and the elongation of the flat filaments are increased, and therefore, the toughness and the falling resistance of the plastic woven bag are improved; the macromolecular chains are arranged in parallel along the direction of external force, and by selecting a relatively small cutter pad, the stretching multiple is reduced, and the elongation consumption during flat filament orientation is reduced, so that the potential elongation deformation capability of the molecular chains is recovered, and the toughness and the falling resistance of the plastic woven bag are improved.

Description

Technical Field

[0001] The invention relates to the field of plastic woven bag preparation, in particular to a high-toughness drop-resistant plastic woven bag and a preparation method thereof. Background Art

[0002] Plastic woven bags are made of polypropylene (PP) and polyethylene (PE) resins as the main raw materials, with a small amount of auxiliary materials added, mixed and melted by an extruder, extruded plastic film cut into filaments, stretched at a temperature lower than the melting temperature of the resin, and made into high-strength, low-elongation flat filaments through molecular orientation and heat setting, and then made into plastic woven bags through winding, weaving, cutting and sewing. Plastic woven bags have the advantages of flatness, high tensile strength, convenient packaging, corrosion resistance, no water absorption, no mildew, easy loading and unloading, stacking, handling and storage.

[0003] The General Technical Requirements for Plastic Woven Bags GB / T 8946-2013 states that the drop resistance height is 1.2 meters, and the quality standard is "the packaging bag is not damaged, and the contents are not leaking. The bag is qualified if the material is not leaking after being lifted from the ground due to the impact from the warp and weft flat wires or the seam holes when it falls." However, in actual use, woven bags filled with materials are often manually thrown down from a height of no less than 1.2 meters, so that the woven bags may be damaged and leak materials in different directions after falling to the ground.

[0004] Therefore, we propose a high-toughness drop-resistant plastic woven bag with high elongation and drop resistance at a height of 2 meters. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art, meet the actual needs, and provide a high-toughness, drop-resistant plastic woven bag and a preparation method thereof, so as to solve the current "General Technical Requirements for Plastic Woven Bags" GB / T 8946-2013, which states that the drop resistance height is 1.2 meters, and the quality standard is "the packaging bag is not damaged, and the contents are not leaked. The material that is impacted from the sealing warp and weft flat wires or the suture holes when falling will not leak after the bag is lifted from the ground, and is qualified". However, in the actual use process, the woven bag filled with materials is often manually thrown down from a height of not less than 1.2 meters, so that the woven bag may be damaged and leak materials in different directions after landing.

[0006] In order to achieve the purpose of the present invention, the technical solution adopted by the present invention is: design a high-toughness anti-drop plastic woven bag, including: 85-100 parts of polypropylene, 3-5 parts of polyethylene, and 5-10 parts of filler;

[0007] The filler contains 10%-15% of LDPE and can induce β-type crystallization.

[0008] Preferably, the polypropylene is one of coal chemical L5E89, Shenhua 1102K and Yulin S1003, and the melt flow index is preferably 2-3.5 g / 10 min.

[0009] Preferably, the polyethylene is one or more of high-density polyethylene and linear low-density polyethylene, and the melt flow index is preferably 0.5-1.2 g / 10 min.

[0010] A method for preparing a high-toughness drop-resistant plastic woven bag is also provided, comprising the following steps:

[0011] S1, using polypropylene as the main raw material, mixing with a small amount of polyethylene, and adding an appropriate amount of filler;

[0012] S2, after mixing, melted by extruder, extruded plastic film passes through knife pad, cut into wires under appropriate stretch multiples, and made into flat wires with high elongation through molecular orientation and heat setting;

[0013] S3, and then through winding, weaving, coating, cutting and sewing, it is made into a high-toughness anti-drop plastic woven bag.

[0014] Preferably, the extrusion melting temperature in S2 is controlled between 240-270° C., and the temperature in each interval increases in a step-by-step manner.

[0015] Preferably, the specification of the knife pad is 4.2-4.4 mm, and accordingly, the stretching ratio is controlled at 5.3-5.5 times.

[0016] Preferably, the high elongation flat yarn has an elongation of at least 22% under a single yarn strength tester, and the plastic woven bag made by winding, weaving, coating, cutting and sewing has a high elongation of more than 25% when tested by a tensile tester, and passes the 2m high bag drop test.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention selects fillers that can induce β-crystals. The polypropylene β-crystals have a loose spherulite structure and can improve the elongation of the flat wire within a certain range. At the same time, polypropylene and polyethylene are blended. The two have similar polarities and good thermodynamic compatibility, which increases the melt viscosity, effectively prevents the flat wire from fluffing and splitting, increases the toughness and elongation of the flat wire, and thus increases the toughness and drop resistance of the plastic woven bag.

[0019] 2. After uniaxial orientation in the wire drawing process, the polymer chains are arranged in parallel along the direction of the external force. By selecting a smaller knife pad, the stretching multiple is reduced, and the elongation consumption during flat wire orientation is reduced, thereby restoring the potential elongation and deformation ability of the molecular chain and increasing the toughness and drop resistance of the plastic woven bag. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0022] A high-toughness, drop-resistant plastic woven bag, see Figure 1 , including: 85-100 parts of polypropylene, 3-5 parts of polyethylene, and 5-10 parts of filler;

[0023] The filler contains 10%-15% LDPE and can induce β-type crystallization.

[0024] For details, see Figure 1 The polypropylene is one of coal chemical L5E89, Shenhua 1102K and Yulin S1003, and the melt flow index is preferably 2-3.5g / 10min.

[0025] For further information, see Figure 1 The polyethylene is one or more of high-density polyethylene and linear low-density polyethylene, and the melt flow index is preferably 0.5-1.2 g / 10 min.

[0026] A method for preparing a high-toughness drop-resistant plastic woven bag comprises the following steps:

[0027] S1, using polypropylene as the main raw material, mixing with a small amount of polyethylene, and adding an appropriate amount of filler;

[0028] S2, after mixing, melted by extruder, extruded plastic film passes through knife pad, cut into wires under appropriate stretch multiples, and made into flat wires with high elongation through molecular orientation and heat setting;

[0029] S3, and then through winding, weaving, coating, cutting and sewing, it is made into a high-toughness anti-drop plastic woven bag.

[0030] It is worth noting that see Figure 1 , the extrusion melt temperature in S2 is controlled between 240-270°C, and the temperature in each interval increases in a step-by-step manner.

[0031] It is worth noting that see Figure 1 The specification of the knife pad is 4.2-4.4mm, and accordingly, the stretching multiple is controlled at 5.3-5.5 times.

[0032] It is worth mentioning that see Figure 1The high elongation flat yarn has an elongation of at least 22% under the single yarn strength tester. The plastic woven bag made by winding, weaving, coating, cutting and sewing has a high elongation of more than 25% when tested by the tensile tester, and it passes the 2m high bag drop test.

[0033] Embodiment 1

[0034] A method for preparing a high-toughness drop-resistant plastic woven bag comprises the following steps:

[0035] S1. Mix 90 parts of L5E89, 3 parts of 7042N and 7 parts of filler and stir evenly;

[0036] S2, the mixed material is melt-extruded into a film through an extruder, and the extrusion temperature is set in five temperature zones from heating to extrusion, namely 240°C, 250°C, 260°C, 265°C, and 270°C;

[0037] S3, the plastic film is cut into filaments with a 4.4mm knife pad and a stretching ratio of 5.3 times, and is made into flat filaments with high elongation through molecular orientation and heat setting. The single filament strength and elongation are measured with a single filament strength tester;

[0038] S4. The monofilament is then wound, woven, coated, cut and sewn to make a high-toughness, drop-resistant plastic woven bag, and the strength and elongation of the bag are measured using a tensile testing machine.

[0039] Comparative Example 1

[0040] A method for preparing a high-toughness drop-resistant plastic woven bag comprises the following steps:

[0041] S1. Mix 90 parts of L5E89, 3 parts of 7042N and 7 parts of filler and stir evenly;

[0042] S2, the mixed material is melt-extruded into a film through an extruder, and the extrusion temperature is set in five temperature zones from heating to extrusion, namely 240°C, 250°C, 260°C, 265°C, and 270°C;

[0043] S3, the plastic film is cut into filaments with a 4.3mm knife pad and a stretching ratio of 6 times, and is made into flat filaments with high elongation through molecular orientation and heat setting. The single filament strength and elongation are measured with a single filament strength tester;

[0044] S4. The monofilament is then wound, woven, coated, cut and sewn to make a high-toughness, drop-resistant plastic woven bag, and the strength and elongation of the bag are measured using a tensile testing machine.

[0045] Comparative Example 2

[0046] A method for preparing a high-toughness drop-resistant plastic woven bag comprises the following steps:

[0047] S1. Mix 90 parts of L5E89 and 7 parts of filler and stir evenly without adding polyethylene;

[0048] S2, the mixed material is melt-extruded into a film through an extruder, and the extrusion temperature is set in five temperature zones from heating to extrusion, namely 240°C, 250°C, 260°C, 265°C, and 270°C;

[0049] S3, the plastic film is cut into filaments with a 4.3mm knife pad and a stretching ratio of 5.3 times, and is made into flat filaments with high elongation through molecular orientation and heat setting. The single filament strength value and elongation are measured with a single filament strength tester;

[0050] S4. The monofilament is then wound, woven, coated, cut and sewn to make a high-toughness, drop-resistant plastic woven bag, and the strength and elongation of the bag are measured using a tensile testing machine.

[0051] The finished bags in Example 1 and Comparative Examples 1 and 2 were tested, wherein:

[0052] Mechanical properties: The tensile properties of the bag were tested in accordance with GB / T8946-2013.

[0053] Bag drop test: refer to GB / T8946-2013 to test the bag's anti-drop performance, and increase the bag drop height to 2m.

[0054] The experimental results are shown in the following table:

[0055]

[0056] The data of Example 1 and Comparative Example 1 show that increasing the stretching multiple causes excessive elongation consumption during orientation of the flat yarn molecules, thereby reducing the potential elongation and deformation capacity of the molecular chain, thereby reducing the toughness and drop resistance of the plastic woven bag.

[0057] The data of Example 1 and Comparative Example 2 show that when polyethylene is added to the formula of Example 1, the elongation of the finished bag is greater than 25%, and is higher than that of Comparative Example 2. This is because polypropylene and polyethylene are blended, and their similar polarities are utilized to have good thermodynamic compatibility, increase melt viscosity, effectively prevent flat wire fuzzing and splitting, increase flat wire toughness and elongation, thereby increasing the toughness and drop resistance of the plastic woven bag.

[0058] In addition, the components designed in the present invention are all universal standard parts or components known to technical personnel in this field. Their structures and principles can be known to technical personnel through technical manuals or through conventional experimental methods. They can be fully implemented by technical personnel in this field. Needless to say, the content protected by the present invention does not involve improvements to internal structures and methods.

[0059] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A high-toughness, drop-resistant plastic woven bag, characterized in that: include: Polypropylene 85-100 parts, polyethylene 3-5 parts, filler 5-10 parts; The filler contains 10%-15% of LDPE and can induce β-type crystallization.

2. The high-toughness anti-drop plastic woven bag as claimed in claim 1, characterized in that: The polypropylene is one of coal chemical L5E89, Shenhua 1102K and Yulin S1003.

3. The high-toughness anti-drop plastic woven bag as claimed in claim 1, characterized in that: The melt flow index of the polypropylene is preferably 2-3.5 g / 10 min.

4. The high-toughness anti-drop plastic woven bag as claimed in claim 1, characterized in that: The polyethylene is one or more of high-density polyethylene and linear low-density polyethylene.

5. The high-toughness anti-drop plastic woven bag as claimed in claim 1, characterized in that: The melt flow index of the polyethylene is preferably 0.5-1.2 g / 10 min.

6. A method for preparing a high-toughness anti-drop plastic woven bag, using the high-toughness anti-drop plastic woven bag as described in claims 1-5, comprising the following steps: S1, using polypropylene as the main raw material, mixing with a small amount of polyethylene, and adding an appropriate amount of filler; S2, after mixing, melted by extruder, extruded plastic film passes through knife pad, cut into wires under appropriate stretch multiples, and made into flat wires with high elongation through molecular orientation and heat setting; S3, and then through winding, weaving, coating, cutting and sewing, it is made into a high-toughness anti-drop plastic woven bag.

7. The method for preparing a high-toughness drop-resistant plastic woven bag according to claim 6, characterized in that: The extrusion melting temperature in S2 is controlled between 240° C. and 270° C., and the temperature in each interval increases in a step-by-step manner.

8. The method for preparing a high-toughness drop-resistant plastic woven bag according to claim 6, characterized in that: The specification of the knife pad is 4.2-4.4 mm, and accordingly, the stretching multiple is controlled at 5.3-5.5 times.

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