Production method of PA / PE high-barrier composite film bag

Abstract

The invention discloses a production method of a PA / PE high-barrier composite film bag. The composite film bag comprises an outer layer, a middle layer and an inner layer, the outer layer is prepared from PA6, glass fibers, maleic anhydride grafted polyethylene, an antioxidant, a slipping agent, an ultraviolet light absorber, titanium dioxide, nano silicon dioxide and polyimide; the middle layer is prepared from EVOH (Ethylene Vinyl Alcohol), polyamide-imide, nano montmorillonite, maleic anhydride grafted polypropylene, an antioxidant, a slipping agent, terpene resin, polyvinylidene chloride and polybutylene terephthalate; the inner layer is prepared from HDPE, LLDPE, mPE, an antistatic agent, silicon dioxide, dioctyl phthalate, an antibacterial agent and polylactic acid. The composite film bag prepared by the invention not only has high barrier property and good strength, but also has various functions.

Description

Technical Field

[0001] This invention relates to a method for producing PA / PE high-barrier composite film bags. Background Technology

[0002] With the rapid development of the modern packaging industry, the requirements for packaging materials are increasing, especially in the food, pharmaceutical, and daily chemical industries, where stricter standards are applied to the barrier properties, safety, environmental friendliness, and cost-effectiveness of packaging materials. Traditional packaging materials, such as single polyethylene (PE) or polyamide (PA) films, often fail to meet the demands of modern packaging in terms of barrier performance, mechanical strength, or environmental friendliness. Therefore, developing a composite film material that combines high barrier properties, excellent mechanical properties, and environmental characteristics is particularly important. Summary of the Invention

[0003] In view of the above-mentioned deficiencies of the prior art, the object of the present invention is: a method for producing PA / PE high-barrier composite film bags.

[0004] The technical solution of the present invention is: a method for producing a PA / PE high-barrier composite film bag, wherein the composite film bag includes an outer layer, a middle layer and an inner layer; The outer layer is composed of PA6, glass fiber, maleic anhydride-grafted polyethylene, antioxidant, slip agent, ultraviolet absorber, titanium dioxide, nano silica, and polyimide; The intermediate layer is composed of EVOH, polyamide-imide, nano-montmorillonite, maleic anhydride-grafted polypropylene, antioxidant, slip agent, terpene resin, polyvinylidene chloride, and polybutylene terephthalate. The inner layer is composed of HDPE, LLDPE, mPE, antistatic agent, silica, dioctyl phthalate, antibacterial agent, and polylactic acid; The production method includes the following steps: (1) The raw materials for the outer layer, middle layer and inner layer are blended separately and sent to their respective extruders for mixing and plasticizing; (2) The molten melt is fed into the die head separately. After the melt merges in the die head, it forms a molten sheet through the flat die head opening. (3) Use an air knife to attach the sheet to the cooling roller and cool it rapidly to form an unshaped sheet. Then, after cooling in a water bath, the sheet is shaped to form a cast sheet. (4) The cast sheet is stretched to form a thin film; (5) Coat the outer surface with a polydopamine coating; (6) Wind up the film; (7) The film roll is processed by a bag making machine, which cuts, seals and punches holes to make a composite film bag.

[0005] Furthermore, the outer layer consists of the following components by mass ratio: PA6 50%, glass fiber 25%, maleic anhydride-grafted polyethylene 6%, antioxidant 2%, slip agent 1%, ultraviolet absorber 4%, titanium dioxide 5%, nano silica 3%, and polyimide 4%.

[0006] Furthermore, the components of the intermediate layer are as follows by mass ratio: 30% EVOH, 25% polyamide-imide, 12% nano-montmorillonite, 6% maleic anhydride-grafted polypropylene, 2% antioxidant, 3% slip agent, 10% terpene resin, 8% polyvinylidene chloride, and 4% polybutylene terephthalate.

[0007] Furthermore, the components of the inner layer are as follows by mass: HDPE 45%, LLDPE 25%, mPE 12%, antistatic agent 3%, silica 2%, dioctyl phthalate 5%, antibacterial agent 5%, and polylactic acid 3%.

[0008] Furthermore, step (5) specifically involves: (51) Dissolve dopamine hydrochloride in a buffer solution to prepare a dopamine solution with a concentration of 5 mg / mL; (52) Rinse the film surface with deionized water to remove surface contaminants, and dry it in a nitrogen atmosphere; (53) Coat the outer surface of the dopamine solution evenly; (54) Gently rinse the film surface with deionized water; (55) Dry the film at 40°C for 2 hours.

[0009] The beneficial effects of this invention are: The outer layer of PA6 and glass fiber provides high strength and rigidity, nano-silica and polyimide enhance wear resistance and high temperature resistance, antioxidants and UV absorbers protect the stability, and maleic anhydride-grafted polyethylene and slip agents improve processing and interlayer bonding. The intermediate layer of EVOH, polyvinylidene chloride and nano-montmorillonite synergistically achieves excellent barrier properties, while polyamide-imide and polybutylene terephthalate enhance mechanical and chemical stability, and maleic anhydride-grafted polypropylene, terpene resin and slip agent ensure good bonding with the inner and outer layers. The inner layers of HDPE, LLDPE, and mPE provide flexibility and heat-sealing properties, while antistatic agents, silica, dioctyl phthalate, and antimicrobial agents meet the special requirements of contact with the contents, and polylactic acid adds environmental protection properties. Dopamine coating can further improve the barrier properties of the film. Detailed Implementation

[0010] To provide a more intuitive and complete understanding of the technical solution of this invention, the following non-limiting features are described: A method for producing a PA / PE high-barrier composite film bag, wherein the composite film bag comprises an outer layer, a middle layer and an inner layer; The outer layer is composed of PA6, glass fiber, maleic anhydride-grafted polyethylene, antioxidant, slip agent, ultraviolet absorber, titanium dioxide, nano silica, and polyimide. The antioxidant is antioxidant 168, the slip agent is erucamide, and the ultraviolet absorber is benzotriazole ultraviolet absorber. The intermediate layer is composed of EVOH, polyamide-imide, nano-montmorillonite, maleic anhydride-grafted polypropylene, antioxidant, slip agent, terpene resin, polyvinylidene chloride, and polybutylene terephthalate. The antioxidant is antioxidant 1010 and the slip agent is oleamide. The inner layer is composed of HDPE, LLDPE, mPE, antistatic agent, silica, dioctyl phthalate, antibacterial agent, and polylactic acid. The antistatic agent is ethoxylated alkylamine, and the antibacterial agent is silver ion-loaded nano zinc oxide. The production method of PA / PE high-barrier composite film bags includes the following steps: (1) The raw materials for the outer layer, middle layer and inner layer are blended separately and sent to their respective extruders for mixing and plasticizing; (2) The molten melt is fed into the die head separately. After the melt merges in the die head, it forms a molten sheet through the flat die head opening. (3) Use an air knife to attach the sheet to the cooling roller and cool it rapidly to form an unshaped sheet. Then, after cooling in a water bath, the sheet is shaped to form a cast sheet. (4) The cast sheet is stretched to form a thin film; (5) Coat the outer surface with a polydopamine coating; (6) Wind up the film; (7) The film roll is processed by a bag making machine, which cuts, seals and punches holes to make a composite film bag.

[0011] The outer layer consists of the following components by mass ratio: PA6 50%, glass fiber 25%, maleic anhydride-grafted polyethylene 6%, antioxidant 2%, slip agent 1%, ultraviolet absorber 4%, titanium dioxide 5%, nano silica 3%, and polyimide 4%.

[0012] The components of the intermediate layer are as follows by mass ratio: 30% EVOH, 25% polyamide-imide, 12% nano-montmorillonite, 6% maleic anhydride-grafted polypropylene, 2% antioxidant, 3% slip agent, 10% terpene resin, 8% polyvinylidene chloride, and 4% polybutylene terephthalate.

[0013] The components of the inner layer are as follows by mass ratio: HDPE 45%, LLDPE 25%, mPE 12%, antistatic agent 3%, silica 2%, dioctyl phthalate 5%, antibacterial agent 5%, polylactic acid 3%.

[0014] Step (5) is as follows: (51) Dissolve dopamine hydrochloride in a buffer solution (such as Tris-HCl buffer, pH 8.5) to prepare a dopamine solution with a concentration of 5 mg / mL; (52) Rinse the film surface with deionized water to remove surface contaminants, and dry it in a nitrogen atmosphere; (53) Coat the outer surface of the dopamine solution evenly; (54) Gently rinse the film surface with deionized water; (55) Dry the film at 40°C for 2 hours.

[0015] The outer layer of PA6 and glass fiber provides high strength and rigidity, while nano-silica and polyimide enhance wear resistance and high-temperature resistance. Antioxidants and UV absorbers provide stable protection, and maleic anhydride-grafted polyethylene and slip agents improve processing and interlayer bonding. The outer glass fiber increases the tensile strength and rigidity of the composite film, enhancing its wear resistance and impact resistance. Maleic anhydride-grafted polyethylene improves the compatibility of PA6 with glass fiber and other additives, ensuring uniform dispersion and good interfacial bonding of each component. The slip agent reduces the coefficient of friction on the outer surface, facilitating smooth operation of the composite film during processing and use. The UV absorber absorbs ultraviolet rays, preventing the outer layer from aging, fading, and performance degradation due to UV exposure. Titanium dioxide gives the outer layer a beautiful white appearance and reflects some sunlight, reducing heat absorption. Nano-silica enhances the hardness and wear resistance of the outer layer, extending its service life. Polyimide further improves the high-temperature resistance and mechanical strength of the outer layer, enabling it to adapt to more extreme usage conditions.

[0016] The synergistic effect of EVOH, polyvinylidene chloride, and nano-montmorillonite in the intermediate layer achieves excellent barrier properties. Polyamide-imide and polybutylene terephthalate enhance mechanical and chemical stability. Maleic anhydride-grafted polypropylene, terpene resin, and slip agent ensure good bonding with the inner and outer layers. The layered structure of nano-montmorillonite significantly extends the permeation path of gases and water vapor, greatly improving barrier performance. Maleic anhydride-grafted polypropylene promotes the compatibility between EVOH, polyamide-imide, and nano-montmorillonite, forming a tightly bonded structure and enhancing the stability of the barrier effect. The slip agent oleamide reduces friction between the intermediate layer and the inner and outer layers, which is beneficial for the molding and processing of the composite film and good interlayer bonding. Terpene resin improves the bonding strength between the intermediate layer and the outer and inner layers, ensuring the overall structural stability of the composite film. Polyvinylidene chloride further enhances the barrier performance of the intermediate layer, especially the barrier effect against oxygen and water vapor. Polybutylene terephthalate increases the dimensional stability and chemical corrosion resistance of the intermediate layer, enabling it to maintain excellent barrier performance in complex environments.

[0017] The inner layers of HDPE, LLDPE, and mPE provide flexibility and heat-sealing properties. Antistatic agents, silica, dioctyl phthalate, and antibacterial agents meet the special requirements of contact with the contents, while polylactic acid adds environmental benefits. The combination of these three polyethylenes provides excellent flexibility, puncture resistance, and heat-sealing performance, ensuring the reliability of the inner layer during the packaging process. The antistatic agent, ethoxylated alkylamine, effectively reduces static electricity accumulation in the inner layer, preventing dust adsorption and electrostatic discharge, thus improving the safety and hygiene of the packaging. Silica acts as an opening agent, preventing adhesion between the inner film layers, facilitating the unfolding and use of the composite film, and improving operational efficiency. Dioctyl phthalate increases the softness and extensibility of the inner layer, allowing it to better adapt to contents of different shapes and sizes. The antibacterial agent, silver ion-loaded nano-zinc oxide, imparts antibacterial properties to the inner layer, inhibiting the growth and reproduction of microorganisms. Polylactic acid improves the biocompatibility and biodegradability of the inner layer, meeting the requirements of environmental protection and sustainable development.

[0018] Dopamine coatings can further improve the barrier properties of thin films. Polydopamine forms a uniform and dense coating on the surface of the composite membrane. This coating increases the path length that gas or liquid molecules need to traverse during permeation, thereby slowing down their permeation rate and improving barrier performance. The composite membrane surface may contain some tiny pores and defects, which are channels for gas and liquid permeation. Polydopamine can fill these pores and defects, making the surface smoother and more continuous, reducing the possibility of permeation. The polydopamine coating can interact strongly with the surface of the composite membrane, enhancing the interfacial adhesion between the coating and the substrate. This good adhesion helps maintain the integrity and stability of the coating, preventing coating peeling or cracking during use, thus maintaining barrier performance. The functional groups in polydopamine (such as hydroxyl and amino groups) can interact with permeating molecules through chemical interactions, such as hydrogen bonding and electrostatic interactions, thereby hindering their permeation. In summary, polydopamine coatings effectively improve the barrier performance of composite membranes through the synergistic effects of multiple mechanisms, including physical barriers, pore filling, enhanced interfacial adhesion, and chemical interactions.

Claims

1. A method of producing a PA / PE high barrier composite film bag, characterized by: The composite film bag comprises an outer layer, an intermediate layer and an inner layer; The outer layer is composed of PA6, glass fiber, maleic anhydride grafted polyethylene, antioxidant, slip agent, ultraviolet absorber, titanium dioxide, nano silicon dioxide and polyimide; The intermediate layer is composed of EVOH, polyamide-imide, nano montmorillonite, maleic anhydride grafted polypropylene, antioxidant, slip agent, terpene resin, polyvinylidene chloride and polybutylene terephthalate; The inner layer is composed of HDPE, LLDPE, mPE, antistatic agent, silica, dioctyl phthalate, antibacterial agent and polylactic acid; The production method comprises the following steps: (1) The raw materials of the outer layer, the intermediate layer and the inner layer are respectively blended and sent into respective extruders for plasticizing and mixing; (2) The molten melt is respectively sent into a die, and the melt is combined in the die to form a molten sheet through a flat die opening; (3) The sheet is attached to a chill roll by an air knife for quenching to form an unformed sheet, which is then cooled in a water bath to form a cast sheet; (4) The cast sheet is stretched to form a film; (5) A polydopamine coating is coated on the surface of the outer layer; (6) The film is wound up; (7) The film roll is processed by a bag making machine to cut, seal and punch to form a composite film bag.

2. The method for producing a PA / PE high-barrier composite film bag according to claim 1, characterized by: The components of the outer layer are in a mass ratio of PA6 50%, glass fiber 25%, maleic anhydride grafted polyethylene 6%, antioxidant 2%, slip agent 1%, ultraviolet absorber 4%, titanium dioxide 5%, nano silicon dioxide 3% and polyimide 4%.

3. The method of producing a PA / PE high barrier composite film bag according to claim 1, characterized by: The components of the intermediate layer are in a mass ratio of EVOH 30%, polyamide-imide 25%, nano montmorillonite 12%, maleic anhydride grafted polypropylene 6%, antioxidant 2%, slip agent 3%, terpene resin 10%, polyvinylidene chloride 8% and polybutylene terephthalate 4%.

4. The method of producing a PA / PE high barrier composite film bag according to claim 1, characterized by: The components of the inner layer are in a mass ratio of HDPE 45%, LLDPE 25%, mPE 12%, antistatic agent 3%, silica 2%, dioctyl phthalate 5%, antibacterial agent 5% and polylactic acid 3%.

5. The method of producing a PA / PE high barrier composite film bag according to claim 1, characterized by: Step (5) is specifically: (51) Dopamine hydrochloride is dissolved in a buffer solution to prepare a dopamine solution with a concentration of 5 mg / mL; (52) The surface of the film is rinsed with deionized water to remove contaminants, and then dried in a nitrogen atmosphere; (53) The dopamine solution is uniformly coated on the surface of the outer layer; (54) The surface of the film is gently rinsed with deionized water; (55) The film is dried at 40°C for 2 hours.