Flexible furl bag antistatic composite material and its melt blending method and application

Abstract

The application discloses a flexible container bag antistatic composite material and a melt blending method for preparing the same and application, and is characterized in that the following steps are adopted: the antistatic agent bistrifluoromethanesulfonimide sodium, maleic anhydride and polypropylene are uniformly premixed in a high-speed mixer, the premixed material is added into a double-screw extruder, and melting, shearing and dispersing are carried out so that the ionic liquid antistatic agent is uniformly dispersed in the polymer matrix, and after extrusion, water cooling, air drying and granulation, the antistatic master batch is obtained. The application significantly reduces the surface resistance of the material, and enables the flexible container bag to have a durable, stable and permanent antistatic function.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a flexible container bag antistatic composite material, its melt blending preparation method, and its application. Background Technology

[0002] Flexible intermediary bags (FIBCs) are flexible transport packaging containers widely used for transporting powdery, granular, and lumpy goods such as food, grains, pharmaceuticals, chemicals, and minerals. Due to their large volume, light weight, and ease of loading and unloading, they hold an irreplaceable dominant position in the packaging material application field. Polypropylene (PP) is a thermoplastic polymer with advantages such as low price, easy molding and processing, and excellent performance. Most existing flexible intermediary bags use PP as the base fabric, but PP has low water absorption and strong electrical insulation properties, with a surface resistivity typically around 10⁻⁶. 16 -10 18 Static electricity, measured in Ω·cm, easily accumulates during use, leading to a series of electrostatic hazards and even accidents. Antistatic flexible container bags can conduct and dissipate the static electricity generated by friction between the packaging fabric and the product during loading and unloading, thus ensuring the safety of goods during the process.

[0003] Type C flexible FIBCs, also known as conductive or grounded flexible FIBCs, are made by weaving conductive flat yarns into non-conductive PP fabric, typically in a mesh pattern. These conductive yarns must be internally interconnected to conduct static electricity to specific grounding points. Throughout the filling and emptying process, these grounding points must be connected to the system grounding point. Type D flexible FIBCs are made of antistatic materials, effectively preventing electrical sparks, brush discharges, and propagating brush discharges. They do not require connection to the ground. Developing PP materials with excellent antistatic properties is key to the production of Type D flexible FIBCs.

[0004] Traditional methods for improving the antistatic properties of PP mainly involve adding antistatic agents or conductive fillers. Adding antistatic agents primarily involves incorporating them into the material during melt blending, ensuring uniform dispersion throughout the polymer. After film stretching or molding, the hydrophilic antistatic agents migrate to the material surface via polymer chain movement, absorbing moisture from the air and forming a water film on the surface, thus dissipating charge. When the antistatic agent on the surface becomes ineffective, internal antistatic agents continue to fill the interface. Conductive filler methods mainly involve dispersing conductive fillers within the PP matrix through mixing, creating conductive pathways or networks within the PP to dissipate charge. However, the antistatic effect of some surfactant-based antistatic agents is often overly dependent on environmental humidity, while the addition of conductive fillers such as carbon black, carbon fiber, and graphite often leads to a loss of the original properties and color of the PP material. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a flexible container bag antistatic composite material, its melt blending preparation method, and its application, which significantly reduces the surface resistance of the material, enabling the flexible container bag to have a long-lasting, stable, and permanent antistatic function.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a method for preparing antistatic composite materials for flexible container bags by melt blending, characterized by the following steps: antistatic agents sodium bis(trifluoromethanesulfonyl)imide (Na-TFSI), maleic anhydride (MA), and polypropylene (PP) are premixed uniformly in a high-speed mixer; the premix is ​​added to a twin-screw extruder for melting, shearing, and dispersion, so that the ionic liquid antistatic agent is uniformly dispersed in the polymer matrix; after extrusion, the mixture is water-cooled, air-dried, and pelletized to obtain antistatic masterbatch.

[0007] In the above scheme, the mass fraction ratio of the antistatic agent sodium bis(trifluoromethanesulfonyl)imide, maleic anhydride and polypropylene is 3-4:0.8-1:95-96.2.

[0008] In the above scheme: the antistatic agent sodium bis(trifluoromethanesulfonyl)imide, maleic anhydride and polypropylene (PP) are dried at 60-80℃ beforehand.

[0009] In the above scheme, the feeding temperature of the twin-screw extruder is 170℃-180℃.

[0010] In the above scheme: the melting temperature is 200℃, the homogenization temperature is 210℃, and the extrusion temperature is 210℃.

[0011] In the above scheme: the screw speed of the twin-screw extruder is 350-400 rpm.

[0012] The method for preparing flexible container bag antistatic composite material by melt blending provides a flexible container bag antistatic composite material.

[0013] The application of the aforementioned antistatic composite material for flexible container bags in the preparation of antistatic flexible container bags.

[0014] This invention uses the ionic liquid Na-TFSI as an antistatic agent. During melt blending, MA undergoes a grafting reaction with the PP matrix to generate MAPP in situ. MA acts as a good compatibilizer for PP and Na-TFSI, effectively reducing the interfacial tension between the two phases and improving the dispersibility of Na-TFSI in the PP matrix, thereby enhancing the antistatic and mechanical properties of the PP / Na-TFSI system. By optimizing the ratio of Na-TFSI, MA, and PP, a composite material with good electrical conductivity and high strength was prepared.

[0015] Na-TFSI, an antistatic agent, is an ionic liquid composed of sodium ions and trifluoromethanesulfonyl imide ions. It possesses unique physicochemical properties such as non-flammability, high conductivity, high heat capacity, low vapor pressure, and stable properties. As an ionic liquid, its strong conductivity allows it to form continuous ion transport channels within the polymer matrix, significantly reducing the surface resistance of the material and giving the flexible container bag a durable and stable permanent antistatic function. Simultaneously, Na-TFSI exhibits good fluidity in its high-temperature melt processing state, effectively filling the varying sizes of pores formed within the antistatic material of the flexible container bag during extrusion and fiber drawing. This eliminates the "open circuit" phenomenon in charge movement channels and improves the yield of extruded fibers due to the densification of the material structure.

[0016] Beneficial effects:

[0017] (1) By using the above technical solution and optimizing the ratio of Na-TFSI to MA, the prepared antistatic masterbatch has excellent antistatic properties. The ionic liquid antistatic agent can form a continuous ion transport channel in the PP matrix, which significantly reduces the surface resistivity of the material.

[0018] (2) Na-TFSI ionic liquid is used, which has better conductivity than traditional antistatic agents, and the surface resistivity of the composite material is reduced to (6.3-7.5)×10. 7 Ω·cm, compared with pure PP without antistatic agent, the surface resistivity is reduced by 9-11 orders of magnitude.

[0019] (3) The tensile strength of the composite material is 3.8%-5% higher than that of pure PP without antistatic agent. By filling defects and eliminating the "open circuit" phenomenon of charge transmission channels, the extrusion and drawing yield is increased by more than 12%. Detailed Implementation

[0020] The present invention will be further described below with reference to embodiments.

[0021] Example 1

[0022] Preparation of Antistatic Composite Materials for Flexible Intermediate Bulk Containers (FIBCs) by Melt Blending

[0023] The antistatic agents Na-TFSI, MA, and PP were pre-dried at 60-80℃. The antistatic agents Na-TFSI, MA, and PP were pre-mixed uniformly in a high-speed mixer at a mass fraction of 3%:0.8%:96.2%. The premixed material was added to a twin-screw extruder for melting, shearing, and dispersion to ensure the ionic liquid antistatic agent was uniformly dispersed in the polymer matrix. After extrusion, the mixture was water-cooled, air-dried, and pelletized to obtain antistatic masterbatch. The feeding temperature of the twin-screw extruder was 170℃-180℃. The melting temperature was 200℃, the homogenization temperature was 210℃, and the extrusion temperature was 210℃. The screw speed of the twin-screw extruder was 350-400 rpm. The surface resistivity of the material was 7.1×10⁻⁶. 7 Ω·cm, tensile strength is 32.5 MPa (the tensile strength of PP is 31.2 MPa).

[0024] Example 2

[0025] Preparation of Antistatic Composite Materials for Flexible Intermediate Bulk Containers (FIBCs) by Melt Blending

[0026] The antistatic agents Na-TFSI, MA, and PP were pre-dried at 60-80℃. The antistatic agents Na-TFSI, MA, and PP were pre-mixed uniformly in a high-speed mixer at a mass fraction of 3.5%: 0.8%: 95.7%. The premixed material was added to a twin-screw extruder for melting, shearing, and dispersion to ensure the ionic liquid antistatic agent was uniformly dispersed in the polymer matrix. After extrusion, the mixture was water-cooled, air-dried, and pelletized to obtain the antistatic masterbatch. The feeding temperature of the twin-screw extruder was 170℃-180℃. The melting temperature was 200℃, the homogenization temperature was 210℃, and the extrusion temperature was 210℃. The screw speed of the twin-screw extruder was 350-400 rpm. The surface resistivity of the material was 6.3×10⁻⁶. 7 Ω·cm, tensile strength 32.7 MPa (the tensile strength of PP is 31.2 MPa).

[0027] Example 3

[0028] Preparation of Antistatic Composite Materials for Flexible Intermediate Bulk Containers (FIBCs) by Melt Blending

[0029] The antistatic agents Na-TFSI, MA, and PP were pre-dried at 60-80℃. The antistatic agents Na-TFSI, MA, and PP were pre-mixed uniformly in a high-speed mixer at a mass fraction of 3.2%: 1%: 95.8%. The premixed material was added to a twin-screw extruder for melting, shearing, and dispersion to ensure the ionic liquid antistatic agent was uniformly dispersed in the polymer matrix. After extrusion, the mixture was water-cooled, air-dried, and pelletized to obtain antistatic masterbatch. The feeding temperature of the twin-screw extruder was 170℃-180℃. The melt temperature was 200℃, the homogenization temperature was 210℃, and the extrusion temperature was 210℃. The screw speed of the twin-screw extruder was 350-400 rpm. The surface resistivity of the material was 7.5×10⁻⁶. 7 Ω·cm, tensile strength 32.4 MPa (the tensile strength of PP is 31.2 MPa).

[0030] Example 4

[0031] Preparation of Antistatic Composite Materials for Flexible Intermediate Bulk Containers (FIBCs) by Melt Blending

[0032] The antistatic agents Na-TFSI, MA, and PP are pre-dried at 60-80℃. The antistatic agents Na-TFSI, MA, and PP are pre-mixed uniformly in a high-speed mixer at a mass fraction of 3%:1%:96%. The premix is ​​then added to a twin-screw extruder for melting, shearing, and dispersion to ensure the ionic liquid antistatic agent is uniformly dispersed in the polymer matrix. After extrusion, the mixture is water-cooled, air-dried, and pelletized to obtain antistatic masterbatch. The feeding temperature of the twin-screw extruder is 170℃-180℃. The melt temperature is 200℃, the homogenization temperature is 210℃, and the extrusion temperature is 210℃. The screw speed of the twin-screw extruder is 350-400 rpm. The surface resistivity of the material is 6.6×10⁻⁶. 7 Ω·cm, tensile strength 32.5 MPa (the tensile strength of PP is 31.2 MPa).

[0033] 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 method for preparing antistatic composite materials for flexible container bags by melt blending, characterized in that, The following steps were followed to prepare the antistatic agent sodium bis(trifluoromethanesulfonyl)imide, maleic anhydride, and polypropylene: the antistatic agent sodium bis(trifluoromethanesulfonyl)imide, maleic anhydride, and polypropylene were premixed evenly in a high-speed mixer. The premix was then added to a twin-screw extruder for melting, shearing, and dispersion to ensure that the ionic liquid antistatic agent was evenly dispersed in the polymer matrix. After extrusion, the mixture was cooled with water, air-dried, and pelletized to obtain the antistatic masterbatch.

2. The method for preparing flexible container bag antistatic composite material by melt blending according to claim 1, characterized in that: The mass fraction ratio of the antistatic agent sodium bis(trifluoromethanesulfonyl)imide, maleic anhydride, and polypropylene is 3-4:0.8-1:95-96.

2.

3. The method for preparing flexible container bag antistatic composite materials by melt blending according to claim 1 or 2, characterized in that: The antistatic agents sodium bis(trifluoromethanesulfonyl)imide, maleic anhydride, and polypropylene are dried at 60-80°C beforehand.

4. The method for preparing flexible container bag antistatic composite material by melt blending according to claim 3, characterized in that: The feeding temperature of the twin-screw extruder is 170℃-180℃.

5. The method for preparing flexible container bag antistatic composite material by melt blending according to claim 4, characterized in that: The melting temperature is 200℃, the homogenization temperature is 210℃, and the extrusion temperature is 210℃.

6. The method for preparing flexible container bag antistatic composite material by melt blending according to claim 5, characterized in that: The screw speed of the twin-screw extruder is 350-400 rpm.

7. A flexible container bag antistatic composite material prepared by the melt blending method according to any one of claims 1-6.

8. The application of the antistatic composite material of the flexible container bag according to claim 7 in the preparation of antistatic flexible container bags.