Food packaging material with low water vapor transmission rate and preparation method and application thereof

Abstract

The application relates to the field of food packaging materials, and particularly discloses a food packaging material with low water vapor permeability, a preparation method and application thereof. The food packaging material with low water vapor permeability comprises the following raw materials in parts by mass: 40-50 parts of polyamide, 10-20 parts of modified polyamide A, 5-15 parts of modified polyamide B, 15-20 parts of polyether ester elastomer, 5-8 parts of a filler, 1-3 parts of an antioxidant and 2-5 parts of a compatilizer. The food packaging material has the advantage of good water vapor barrier property.

Description

Technical Field

[0001] This application relates to the field of food packaging materials, and more specifically, to a food packaging material with low water vapor permeability, its preparation method, and its application. Background Technology

[0002] With the increasing demands for food safety, hygiene, and convenience in modern society, the technological development of food packaging materials has received growing attention. Among these, retort-resistant packaging materials, as a crucial element in ensuring long-term safe storage of food, are finding increasingly widespread application in areas such as pre-prepared dishes and medical nutrition meals. Currently, widely used materials include polyethylene, polylactic acid, and polyamide. Polyethylene packaging materials dominate due to their low cost, good flexibility, and ease of processing; however, their gas barrier properties are poor, exhibiting a significant weakness in blocking oxygen. Polylactic acid packaging materials demonstrate significant advantages in environmental protection, but their insufficient flexibility and impact resistance, along with their low heat resistance, make them unsuitable for food packaging scenarios requiring high-temperature sterilization or hot-filling.

[0003] Polyamide packaging materials are typically made primarily of nylon 6 and nylon 66, possessing excellent mechanical strength and low oxygen permeability, making them suitable for packaging easily oxidized and perishable products such as cooked food, meat, and cheese. They also exhibit relatively good temperature resistance (-30℃ to 135℃), giving them application potential in emerging and popular fields such as ready-to-eat meals and ready-to-eat packs. However, polyamide materials have strong hygroscopic properties; absorbing water can easily lead to dimensional changes, decreased barrier properties, and the formation of bubbles during cooking, affecting appearance and sealing reliability.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] In order to obtain a food packaging material with good water vapor barrier effect and low water vapor permeability, this application provides a food packaging material with low water vapor permeability, its preparation method, and its application.

[0006] In a first aspect, this application provides a food packaging material with low water vapor permeability, employing the following technical solution:

[0007] A food packaging material with low water vapor permeability, comprising the following raw materials in parts by weight:

[0008] 40-50 parts polyamide, 10-20 parts modified polyamide A, 5-15 parts modified polyamide B, 15-20 parts polyether ester elastomer, 5-8 parts filler, 1-3 parts antioxidant, 2-5 parts compatibilizer;

[0009] The modified polyamide A is obtained by a ring-opening reaction between an amino-terminated polyamide and a multifunctional epoxy siloxane;

[0010] The modified polyamide B is a shellac-modified hyperbranched polyamide; the filler is nano-sized montmorillonite with a silane coupling agent surface modified; the mass ratio of the modified polyamide B to the filler is (1-2):1.

[0011] Preferably, the multifunctional epoxy siloxane is a difunctional epoxy siloxane, specifically a bis(glycidoxypropyl)-terminated polydimethylsiloxane.

[0012] Preferably, the modified polyamide B is obtained by carboxyl-amino condensation reaction of shellac acid and amino-containing hyperbranched polyamide.

[0013] Preferably, the filler is nanoscale montmorillonite surface-modified with γ-glycidoxypropyltrimethoxysilane.

[0014] Preferably, the polyamide is selected from one or more of PA6, PA66, PA610, PA1010, and PA12.

[0015] Preferably, the antioxidant is selected from one or more of hindered phenolic antioxidants and phosphite antioxidants;

[0016] The compatibilizer is maleic anhydride-grafted polyolefin.

[0017] Preferably, the filler is compounded with the modified polyamide B and then blended with other components.

[0018] Preferably, the method for preparing the food packaging material includes the following steps:

[0019] According to the formula, modified polyamide B, filler and antioxidant are melt-extruded and granulated at 210-230℃ to obtain modified masterbatch;

[0020] According to the formula, polyamide, modified polyamide A, modified masterbatch, polyether ester elastomer and compatibilizer are mixed evenly, melt extruded at 240-260℃, and blown into film to obtain food packaging material.

[0021] Secondly, this application provides a method for preparing a food packaging material with low water vapor permeability, using the following technical solution:

[0022] According to the formula, modified polyamide B, filler and antioxidant are melt-extruded and granulated at 210-230℃ to obtain modified masterbatch;

[0023] According to the formula, polyamide, modified polyamide A, modified masterbatch, polyether ester elastomer and compatibilizer are mixed evenly, melt extruded at 240-260℃, and blown into film to obtain food packaging material.

[0024] Thirdly, this application provides the application of the food packaging material with low water vapor permeability or the food packaging material prepared by the above-mentioned method in the packaging of pre-prepared foods.

[0025] In summary, this application has the following beneficial effects:

[0026] 1. By adding modified polyamide A containing an organosilicon segment structure and modified polyamide B that can anchor with the filler, a dual protection system combining an organosilicon segment hydrophobic network and a chemically anchored montmorillonite sheet physical barrier network is constructed, which effectively extends the water vapor diffusion path and plays a highly efficient water vapor barrier role.

[0027] 2. This application optimizes the preparation steps of food packaging materials by using a two-step method of first compounding and then blending to achieve effective chemical anchoring of filler and modified polyamide B. This helps maintain the uniform distribution and directional arrangement of montmorillonite in the packaging material, forming a more continuous physical barrier network and promoting the water vapor barrier performance of montmorillonite. It also improves the interfacial transmission of stress, which is conducive to further improving the mechanical strength and dimensional stability of the material. Detailed Implementation

[0028] To further aid in understanding the technical solution of this invention, several specific implementation examples are provided below to describe the technical solution of this invention in more detail. All described embodiments are only some embodiments of this invention, not all of them. It should be understood that the following description is merely illustrative and is not intended to limit the scope of this invention. The scope of protection of this invention is defined by the appended claims. Furthermore, those skilled in the art will understand that modifications can be made to the technical solution of this invention without departing from the spirit and intent of this invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter pertains. Before a detailed description of the invention, the following definitions are provided to better understand it.

[0030] In cases where numerical ranges are provided, such as concentration ranges, percentage ranges, or ratio ranges, it should be understood that, unless the context explicitly specifies otherwise, all intermediate values ​​between the upper and lower limits of the range, up to one-tenth of the lower limit unit, and any other values ​​or intermediate values ​​within the range are included in the subject matter. The upper and lower limits of these smaller ranges may be independently included in the smaller ranges, and such embodiments are also included in the subject matter, limited by any specific excluded limit values ​​within the range. Where the range includes one or two limit values, the range excluding any one or both of those included limit values ​​is also included in the subject matter.

[0031] In the context of this invention, many embodiments use the expressions "comprising," "including," or "basically / mainly composed of." The expressions "comprising," "including," or "basically / mainly composed of" are generally understood as open-ended expressions, indicating that they include not only the elements, components, parts, or method steps specifically listed after the expression, but also other elements, components, parts, or method steps. However, in this document, the expressions "comprising," "including," or "basically / mainly composed of" can also be understood as closed-ended expressions in certain cases, indicating that they only include the elements, components, parts, or method steps specifically listed after the expression, and do not include any other elements, components, parts, or method steps. In this case, the expression is equivalent to the expression "composed of."

[0032] To better understand this teaching and without limiting its scope, all figures and other numerical values ​​used in the specification and claims to express quantities, percentages, or proportions should, in all cases, be understood to be modified by the term "about." Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​that may vary depending on the desired properties sought. At a minimum, each numerical parameter should be interpreted based at least on the reported significant figures and by applying common rounding techniques.

[0033] In the context of the invention, ordinal numbers such as “first,” “second,” “third,” or “(1),” “(2),” “(3)” are used to describe the invention. It should be understood that the purpose of using ordinal numbers is only to distinguish the different components, structures, elements, steps, etc. involved in the description of the invention, and is not intended to limit the order or hierarchy of these different components, structures, elements, steps, etc., unless explicitly stated in the context.

[0034] In order to obtain food packaging materials with good water vapor barrier properties, this application provides a food packaging material with low water vapor permeability, its preparation method, and its application.

[0035] In a first aspect, this application provides a food packaging material with low water vapor permeability, comprising the following raw materials in parts by weight:

[0036] 40-50 parts polyamide, 10-20 parts modified polyamide A, 5-15 parts modified polyamide B, 15-20 parts polyether ester elastomer, 5-8 parts filler, 1-3 parts antioxidant, and 2-5 parts compatibilizer.

[0037] In a preferred embodiment, the polyamide is selected from one or more of PA6, PA66, PA610, PA1010, and PA12. Polyamide-based packaging materials generally possess excellent mechanical strength and low oxygen permeability. To improve the moisture barrier properties of polyamide-based packaging materials, this application improves the packaging material formulation by adding modified polyamide components and barrier fillers. Specifically,

[0038] In a preferred embodiment, the modified polyamide A is obtained by a ring-opening reaction between an amino-terminated polyamide and a polyfunctional epoxysiloxane. More preferably, the polyfunctional epoxysiloxane is a difunctional epoxysiloxane, specifically a bis(glycidoxypropyl)-terminated polydimethylsiloxane.

[0039] In a preferred embodiment, modified polyamide A can be obtained by melt graft co-extrusion. Specifically, terminal amino polyamide and multifunctional epoxy siloxane are grafted under nitrogen atmosphere, followed by vacuum devolatilization and curing to obtain modified polyamide A masterbatch. The terminal amino polyamide can be derived from commercially available linear or branched terminal amino polyamides, or obtained by melt polycondensation of amide monomers. In this application, the reaction amount of epoxy siloxane can be adjusted according to the molecular weight and functionality of the terminal amino polyamide prepolymer. Specifically, the reaction mass ratio of the terminal amino polyamide prepolymer to the multifunctional epoxy siloxane can be 100:(20-200).

[0040] This application improves the compatibility between low-polarity organosilicon segments and polyamide segments by adding modified polyamide containing organosiloxane segments. It introduces the Si-O-Si structure of polydimethylsiloxane into the polyamide system, reduces the overall polarity of the material, reduces the adsorption and diffusion of water molecules, and helps to improve the overall water vapor barrier performance of the composite film and reduce the water vapor permeability.

[0041] The polyamide segments of modified polyamide A are well miscible with the polyamide matrix and have good dispersibility. The low-polarity siloxane segments can accumulate at the interface of the amorphous region on the surface and inside the packaging material, filling the free volume and shielding the hydrophilic groups. Furthermore, it can form a gradient compatibility interface with modified polyamide B through hydrogen bonding or polar interactions, effectively bridging weakly polar components such as polyether ester elastomers and suppressing phase separation defects. In addition, its flexible siloxane chains can promote the uniform dispersion of fillers and construct a highly tortuous "maze" barrier path in the system, promoting the realization of the inorganic barrier effect of the filler.

[0042] In a preferred embodiment, the modified polyamide B is a shellac-modified hyperbranched polyamide.

[0043] In a preferred embodiment, modified polyamide B can be obtained by a condensation reaction of shellac acid and an amino-containing hyperbranched polyamide. Specifically, the modified polyamide B can be prepared by: activating the carboxyl group of shellac acid using an EDC / NHS system to obtain activated shellac acid; then mixing the activated shellac acid with an amino-containing hyperbranched polyamide to undergo a carboxyl-amino condensation reaction.

[0044] By introducing long-chain shellac acid (9,10,16-trihydroxyhexadecanoic acid, also known as poppy tung acid) grafted with unit amines, modified hyperbranched polyamides can form hydrogen bonds or covalent connections with the polyamide matrix and modified polyamide A, achieving good compatibility. They can also participate in the formation of the polyamide hydrogen bond network, enriching the hydrogen bond network, extending the water vapor diffusion path, and reducing the diffusion rate of water vapor molecules. The shellac acid unit contains long alkyl chains and multiple aliphatic hydroxyl groups. On the one hand, it has good affinity with the soft segments of polyether ester elastomers (such as polyether and polyester), effectively reducing interfacial tension, refining the elastomer dispersion phase, and improving the material's impact resistance while mitigating embrittlement caused by the introduction of rigid fillers. On the other hand, the hydroxyl groups of shellac acid enhance the coating and anchoring effect of the modified hyperbranched polyamide on the filler, significantly promoting the peeling and uniform dispersion of the filler in the polyamide matrix, enhancing the barrier effect of the filler, and can also combine with the filler through the active groups of shellac acid, playing a certain compatibilizer effect and promoting stress transfer between the phases of each component.

[0045] In a preferred embodiment, the polyether ester elastomer may be TPEE. Polyether ester elastomers have good compatibility with polyamide systems, which helps stabilize the toughness and processability of the material.

[0046] In a preferred embodiment, the filler is a nanoscale layered silicate surface-modified with a coupling agent. More preferably, the filler is nanoscale montmorillonite modified with a silane coupling agent, wherein the silane coupling agent is preferably KH560 (γ-glycidoxypropyltrimethoxysilane).

[0047] Layered montmorillonite dispersed in the system forms a physical barrier layer, extending the water vapor permeation path and exhibiting excellent water vapor barrier properties. In a preferred embodiment, the filler can be prepared by dissolving a silane coupling agent in an aqueous ethanol solution with a mass fraction of 5-8%, adjusting the pH to 4-5, adding nano-sized montmorillonite at a mass-to-volume ratio of 1:4-10 g / ml, dispersing evenly, stirring at 60-80℃ for 2-4 h, filtering, washing, and drying to obtain silane coupling agent-modified nano-sized montmorillonite.

[0048] In a preferred embodiment, to improve the stability of the packaging material, an antioxidant is added to the system. The antioxidant can be selected from one or more hindered phenolic antioxidants and phosphite antioxidants. To improve the compatibility between the components, maleic anhydride-grafted polyolefin can be added as a compatibilizer.

[0049] Other additives may also be added as needed in this application, such as dispersants (e.g., ethylene wax, ethylene-vinyl acetate wax, monopolyester wax, stearates (calcium stearate, magnesium stearate, zinc stearate), amide waxes (vinyl bis-stearamide EBS, erucamide, oleamide)) to improve dispersibility and processing performance; and antistatic agents (e.g., cationic surfactants, anionic surfactants) to improve the antistatic properties of the material.

[0050] In a preferred embodiment, the filler is melt-co-extruded with the modified polyamide B, and then blended and extruded with other components.

[0051] In a preferred embodiment, the mass ratio of the modified polyamide B to the filler is (1-2):1.

[0052] In a specific implementation plan, the preparation method of the food packaging material includes the following steps: according to the formula, modified polyamide B, filler, and antioxidant are melt-extruded and granulated at 210-230℃ to obtain modified masterbatch; according to the formula, polyamide, modified polyamide A, modified masterbatch, polyether ester elastomer, and compatibilizer are mixed evenly, melt-extruded at 220-240℃, and blown into film to obtain food packaging material.

[0053] Under melt processing conditions, the hydroxyl groups of the shellac-grafted units of modified polyamide B can form chemical bonds with the silane coupling agent molecules grafted onto the filler surface, achieving chemical anchoring between the filler and modified polyamide B. The system compatibility of modified polyamide, the compatibility of shellac with other components, and the hyperbranched structure improve the dispersibility and compatibility of montmorillonite filler in the polyamide system, establishing a stable interfacial link between the polyamide organic network system and the montmorillonite lamellar network. This reduces the migration and peeling of montmorillonite during granulation and blown film production, maintaining the uniform distribution and directional arrangement of montmorillonite in the packaging material. This facilitates the formation of a more continuous physical barrier network, promoting the water vapor barrier performance of montmorillonite and effectively extending the water vapor diffusion path. Furthermore, the "molecular sealing layer" formed by modified polyamide B at the filler-matrix interface further reduces interfacial microporosity, effectively inhibiting water molecule penetration along the interface. On the other hand, it also improves the interfacial stress transfer, which is beneficial for further improving the mechanical strength and dimensional stability of the material, reducing the possibility of dimensional changes in the packaging material after high-temperature cooking.

[0054] In a preferred embodiment, the molecular weight of the hyperbranched polyamide is 800-1500 g / mol; the mass ratio of the shellac acid to the hyperbranched polyamide can be (0.4-1):1.

[0055] In a second aspect, this application provides a method for preparing a food packaging material with low water vapor permeability, employing the following technical solution:

[0056] According to the formula, modified polyamide B, filler and antioxidant are melt-extruded and granulated at 210-230℃ to obtain modified masterbatch;

[0057] According to the formula, polyamide, modified polyamide A, modified masterbatch, polyether ester elastomer and compatibilizer are mixed evenly, melt extruded at 220-240℃, and blown into film to obtain food packaging material.

[0058] In a third aspect, this application provides the application of a food packaging material with low water vapor permeability or a food packaging material with low water vapor permeability prepared by the above-mentioned method in the packaging of pre-prepared foods.

[0059] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments; and the reaction apparatus, monomer compounds, etc. involved in the following embodiments are all commercially available. Specifically, the raw material grades / types that can be used in the following embodiments include:

[0060] Polyamide PA6: DuPont FG7301 NC010; Hyperbranched polyamide: HyPer N101, HyPer N102, HyPer N103; Bis(glycidoxypropyl)-terminated polydimethylsiloxane: Gelest DMS-E09; Polyether ester elastomer TPEE: DuPont Hytrel 4053FG; Hindered phenolic antioxidant: Antioxidant 1010; Phosphite antioxidant: Antioxidant 168; Maleic anhydride grafted polyolefin: AMPLIFY™ GR 216; Nanoscale montmorillonite: Fenghong New Materials DK1N.

[0061] Example

[0062] Example 1

[0063] This embodiment discloses a food packaging material, the preparation method of which is as follows;

[0064] (1) Raw material preparation

[0065] Modified polyamide A was prepared by the following method:

[0066] Ethylenediamine and adipic acid were dissolved in water at a molar ratio of 1.2:1, with the solid content controlled at approximately 50%. The mixture was stirred at room temperature for 30 minutes, dehydrated under reduced pressure at 60°C, and dried under vacuum at 80°C. The dried nylon salt was added to a reactor and reacted at 100°C for 30 minutes, 160°C for 1 hour, and then at 200°C for 2-3 hours under nitrogen atmosphere. After vacuum dehydration for 30 minutes, the mixture was cooled, pulverized, and granulated to obtain amino-terminated polyamide.

[0067] The di(glycidoxypropyl)-terminated polydimethylsiloxane DMS-E09 was degassed under reduced pressure at 60°C.

[0068] 1000g of amino-terminated polyamide, 1300g of bis(glycidoxypropyl)-terminated polydimethylsiloxane DMS-E09, and 2.3g of catalyst DABCO were added to a reactor. The mixture was heated to 80°C under nitrogen atmosphere and stirred for about 40 minutes. The temperature was then raised to 95°C and reacted for 5 hours. The mixture was then cooled to 80°C and discharged while hot. After cooling, the mixture was pulverized and granulated to obtain modified polyamide A.

[0069] Modified polyamide B was prepared by the following method:

[0070] Dissolve 750g of shellac acid in 1.2L of DMF, add 460g of EDC·HCl and 275g of NHS, and stir the reaction in a light-protected reactor for 1h to obtain an activated shellac acid solution.

[0071] 1000g of hyperbranched polyamide Hyper N102 (molecular weight approximately 1000g / mol) was dissolved in 1.2L of DMF and added to the above-mentioned shellac acid activation solution. The mixture was heated to 50℃ in a nitrogen atmosphere and stirred for 16h. After the reaction was completed, the mixture was cooled to room temperature, and pre-cooled methanol was added to the reaction solution to precipitate the precipitate. The precipitate was separated and collected, washed three times with methanol and acetone, and dried under vacuum at 45℃ to obtain modified polyamide B.

[0072] Silane coupling agent modified nano-sized montmorillonite was prepared by the following method:

[0073] Nanoscale montmorillonite was vacuum dried at 120℃ for 4 hours;

[0074] Dissolve silane coupling agent KH560 in a 90% (w / w) aqueous ethanol solution to prepare a 5% coupling agent solution, adjust the pH to approximately 4.5, and stir for 20 min.

[0075] Take 100g of nano-sized montmorillonite, add it to 600g of coupling agent solution, ultrasonically disperse for 20min, stir at 60℃ for 2h, filter and wash, and vacuum dry at 65℃ for 48h to obtain silane coupling agent modified nano-sized montmorillonite.

[0076] (2) Preparation of food packaging materials:

[0077] All raw materials were vacuum dried at 80℃ for 24 hours and then set aside for use.

[0078] 12 parts by weight of modified polyamide B, 6 parts by weight of silane coupling agent modified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0079] The prepared modified masterbatch, 50 parts by weight of polyamide PA6, 16 parts by weight of modified polyamide A, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0080] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0081] Example 2

[0082] The difference between this embodiment and Embodiment 1 is that the preparation method of the food packaging material is as follows:

[0083] Modified polyamide A, modified polyamide B, and silane coupling agent-modified nano-sized montmorillonite were prepared using the method described in Example 1.

[0084] All raw materials were vacuum dried at 80℃ for 24 hours and then set aside for use.

[0085] 14 parts by weight of modified polyamide B, 8 parts by weight of silane coupling agent modified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0086] The prepared modified masterbatch, 50 parts by weight of polyamide PA6, 12 parts by weight of modified polyamide A, 18 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0087] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0088] Example 3

[0089] The difference between this embodiment and Embodiment 1 is that the preparation method of the food packaging material is as follows:

[0090] Modified polyamide A, modified polyamide B, and silane coupling agent-modified nano-sized montmorillonite were prepared using the method described in Example 1.

[0091] All raw materials were vacuum dried at 80℃ for 24 hours and set aside for later use.

[0092] 50 parts by weight of polyamide PA6, 16 parts by weight of modified polyamide A, 12 parts by weight of modified polyamide B, 6 parts by weight of silane coupling agent modified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, 0.5 parts by weight of antioxidant 1010, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin were put into a high-speed mixer and mixed evenly. The mixture was then melt-extruded and granulated at 240-260℃ to obtain packaging material masterbatch.

[0093] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0094] Example 4

[0095] The difference between this embodiment and Embodiment 1 is that the preparation method of the food packaging material is as follows:

[0096] Modified polyamide A, modified polyamide B, and silane coupling agent-modified nano-sized montmorillonite were prepared using the method described in Example 1.

[0097] All raw materials were vacuum dried at 80℃ for 24 hours and set aside for later use.

[0098] 10 parts by weight of modified polyamide B, 8 parts by weight of silane coupling agent modified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0099] The prepared modified masterbatch, 50 parts by weight of polyamide PA6, 16 parts by weight of modified polyamide A, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0100] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0101] Example 5

[0102] The difference between this embodiment and Embodiment 1 is that the preparation method of the food packaging material is as follows:

[0103] Modified polyamide B was prepared by the following method:

[0104] Dissolve 750g of shellac acid in 1.2L of DMF, add 460g of EDC·HCl and 275g of NHS, and stir the reaction in a light-protected reactor for 1h to obtain an activated shellac acid solution.

[0105] 1000g of hyperbranched polyamide Hyper N101 (molecular weight approximately 360g / mol) solution was added to 1.2L of DMF and then to the above-mentioned shellac acid activation solution. The mixture was heated to 50℃ under nitrogen atmosphere and stirred for 16h. After the reaction was completed, the mixture was cooled to room temperature, and pre-cooled methanol was added to the reaction solution to precipitate the precipitate. The precipitate was separated and collected, washed three times with methanol and acetone, and dried under vacuum at 45℃ to obtain modified polyamide B.

[0106] Nanoscale montmorillonite modified with modified polyamide A and silane coupling agent was prepared according to the method in Example 1;

[0107] All raw materials were vacuum dried at 80℃ for 24 hours and set aside for later use.

[0108] 12 parts by weight of modified polyamide B, 6 parts by weight of silane coupling agent modified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0109] The prepared modified masterbatch, 50 parts by weight of polyamide PA6, 16 parts by weight of modified polyamide A, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0110] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0111] Example 6

[0112] The difference between this embodiment and Embodiment 1 is that the preparation method of the food packaging material is as follows:

[0113] Modified polyamide B was prepared by the following method:

[0114] Dissolve 750g of shellac acid in 1.2L of DMF, add 460g of EDC·HCl and 275g of NHS, and stir the reaction in a light-protected reactor for 1h to obtain an activated shellac acid solution.

[0115] 1000g of hyperbranched polyamide Hyper N103 (molecular weight approximately 2000g / mol) solution was added to 1.2L of DMF and then to the above-mentioned shellac acid activation solution. The mixture was heated to 50℃ under nitrogen atmosphere and stirred for 16h. After the reaction was completed, the mixture was cooled to room temperature, and pre-cooled methanol was added to the reaction solution to precipitate the precipitate. The precipitate was separated and collected, washed three times with methanol and acetone, and dried under vacuum at 45℃ to obtain modified polyamide B.

[0116] Nanoscale montmorillonite modified with modified polyamide A and silane coupling agent was prepared according to the method in Example 1;

[0117] All raw materials were vacuum dried at 80℃ for 24 hours and set aside for later use.

[0118] 12 parts by weight of modified polyamide B, 6 parts by weight of silane coupling agent modified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0119] The prepared modified masterbatch, 50 parts by weight of polyamide PA6, 16 parts by weight of modified polyamide A, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0120] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0121] Comparative Example

[0122] Comparative Example 1

[0123] The difference between this comparative example and Example 1 is that the preparation method of the food packaging material is as follows:

[0124] Nanoscale montmorillonite modified with modified polyamide B and silane coupling agent was prepared according to the method in Example 1;

[0125] All raw materials were vacuum dried at 80℃ for 24 hours and then set aside for use.

[0126] 12 parts by weight of modified polyamide B, 6 parts by weight of silane coupling agent modified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0127] The prepared modified masterbatch, 50 parts by weight of polyamide PA6, 16 parts by weight of modified polyamide B, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0128] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0129] Comparative Example 2

[0130] The difference between this comparative example and Example 1 is that the preparation method of the food packaging material is as follows:

[0131] Nanoscale montmorillonite modified with modified polyamide A and silane coupling agent was prepared according to the method in Example 1;

[0132] All raw materials were vacuum dried at 80℃ for 24 hours and then set aside for use.

[0133] 12 parts by weight of modified polyamide A, 6 parts by weight of silane coupling agent modified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0134] The prepared modified masterbatch, 50 parts by weight of polyamide PA6, 16 parts by weight of modified polyamide A, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0135] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0136] Comparative Example 3

[0137] The difference between this comparative example and Example 1 is that the preparation method of the food packaging material is as follows:

[0138] Modified polyamide A and modified polyamide B were prepared according to the method in Example 1.

[0139] All raw materials were vacuum dried at 80℃ for 24 hours and set aside for later use.

[0140] 12 parts by weight of modified polyamide B, 6 parts by weight of unmodified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0141] The prepared modified masterbatch, 50 parts by weight of polyamide PA6, 16 parts by weight of modified polyamide A, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0142] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0143] Comparative Example 4

[0144] The difference between this comparative example and Example 1 is that the preparation method of the food packaging material is as follows:

[0145] Modified polyamide B was prepared by the following method:

[0146] Ethylenediamine and adipic acid were dissolved in water at a molar ratio of 1.2:1, with the solid content controlled at approximately 50%. The mixture was stirred at room temperature for 30 minutes, dehydrated under reduced pressure at 60°C, and dried under vacuum at 80°C. The dried nylon salt was added to a reactor and reacted at 100°C for 30 minutes, 160°C for 1 hour, and then at 200°C for 2-3 hours under nitrogen atmosphere. After vacuum dehydration for 30 minutes, the mixture was cooled, pulverized, and granulated to obtain amino-terminated polyamide.

[0147] Dissolve 750g of shellac acid in 1.2L of DMF, add 460g of EDC·HCl and 275g of NHS, and stir the reaction in a light-protected reactor for 1h to obtain an activated shellac acid solution.

[0148] 1000g of amino-terminated polyamide was dissolved in 1.2L of DMF and added to the above shellac activation solution. The mixture was heated to 50℃ in a nitrogen atmosphere and stirred for 16h. After the reaction was completed, the mixture was cooled to room temperature, and pre-cooled methanol was added to the reaction solution to precipitate the precipitate. The precipitate was separated and collected, washed three times with methanol and acetone, and dried under vacuum at 45℃ to obtain modified polyamide B.

[0149] Modified polyamide A was prepared according to the method in Example 1.

[0150] All raw materials were vacuum dried at 80℃ for 24 hours and set aside for later use.

[0151] 12 parts by weight of modified polyamide B, 6 parts by weight of unmodified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0152] The prepared modified masterbatch, 50 parts by weight of polyamide PA6, 16 parts by weight of modified polyamide A, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0153] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0154] Comparative Example 5

[0155] The difference between this comparative example and Example 1 is that the preparation method of the food packaging material is as follows:

[0156] All raw materials were vacuum dried at 80℃ for 24 hours and set aside for later use.

[0157] 12 parts by weight of polyamide PA6, 6 parts by weight of unmodified nano-sized montmorillonite, 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of antioxidant 1010 were put into a mixer and mixed evenly. The mixture was then melt-extruded and granulated at 210-230℃ to obtain the modified masterbatch.

[0158] The prepared modified masterbatch, 66 parts by weight of polyamide PA6, 16 parts by weight of TPEE, and 3 parts by weight of maleic anhydride grafted polyolefin are put into a high-speed mixer and mixed evenly. The mixture is then melt-extruded and granulated at 240-260℃ to obtain the packaging material masterbatch.

[0159] The packaging material masterbatch is added to a blown film machine, heated and blown into film, cooled and pressed at the edges, then slit and bagged to obtain food packaging material.

[0160] Performance testing

[0161] Samples of food packaging materials from each embodiment and comparative example were tested as follows:

[0162] Samples were cut according to GB / T 1040.3-2006 and cured for 48 hours at a temperature of 23±2℃ and a relative humidity of 50±10%. Tensile properties were then tested. Each sample was then boiled at 135℃ for 1 hour. After boiling, the samples were rapidly cooled to room temperature with cold water, the surface moisture was wiped dry, and the samples were cured for 24 hours under the same temperature and humidity conditions. Tensile properties were then tested, and the rate of change of tensile strength was calculated (rate of change of tensile strength = tensile strength after boiling / tensile strength before boiling × 100%).

[0163] Samples were cut according to GB / T 26253-2010 and cured for 12 hours at a temperature of 23±2℃ and a relative humidity of 50±10%. The water vapor transmission rate of the material was tested at 38℃ and a relative humidity difference of 90% RH: 0% RH.

[0164] The test results are summarized in Table 1.

[0165] Table 1

[0166]

[0167] As can be seen from Examples 1-6 and Comparative Examples 1-3 and Comparative Example 5, by referring to the method disclosed in this application, the modified polyamide-based food packaging material is modified with modified polyamide A and modified polyamide B-silane coupling agent modified montmorillonite composite material, which improves the water vapor barrier performance and dimensional stability of the polyamide-based food packaging material and enriches the application of polyamide-based food packaging material in the field of pre-made food packaging.

[0168] As can be seen from Examples 1 and 3, the two-step reaction first involves melt co-extrusion of modified polyamide B and filler, followed by composite extrusion with other components. This allows modified polyamide B to anchor the filler through chemical bonds via its active groups, promoting the effective composite of the organic network and physical sheet barrier layer, which is beneficial for improving the water vapor barrier effect of the material.

[0169] As can be seen from Examples 1, 5-6, and Comparative Example 4, by using hyperbranched polyamide and controlling the molecular weight of hyperbranched polyamide, the water vapor barrier effect and tensile properties of the material can be made more stable within the scope of this application, which is beneficial to ensuring the dimensional stability of the material.

[0170] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A food packaging material with low water vapor permeability, characterized in that, The following raw materials are included in parts by weight: 40-50 parts polyamide, 10-20 parts modified polyamide A, 5-15 parts modified polyamide B, 15-20 parts polyether ester elastomer, 5-8 parts filler, 1-3 parts antioxidant, 2-5 parts compatibilizer; The modified polyamide A is obtained by a ring-opening reaction between an amino-terminated polyamide and a multifunctional epoxy siloxane; The modified polyamide B is obtained by carboxyl-amino condensation reaction of shellac acid and amino-containing hyperbranched polyamide. The filler is nano-sized montmorillonite modified with a silane coupling agent; the mass ratio of the modified polyamide B to the filler is (1-2):1; The multifunctional epoxy siloxane is a bis(glycidoxypropyl)-terminated polydimethylsiloxane.

2. The food packaging material with low water vapor permeability according to claim 1, characterized in that, The filler is specifically nanoscale montmorillonite with γ-glycidoxypropyltrimethoxysilane surface modification.

3. The food packaging material with low water vapor permeability according to claim 1, characterized in that, The polyamide is selected from one or more of PA6, PA66, PA610, PA1010, and PA12.

4. The food packaging material with low water vapor permeability according to claim 1, characterized in that, The antioxidant is selected from one or more hindered phenolic antioxidants and phosphite antioxidants; The compatibilizer is maleic anhydride-grafted polyolefin.

5. The food packaging material with low water vapor permeability according to claim 1, characterized in that, The filler and the modified polyamide B are melt co-extruded together, and then blended and extruded with other components.

6. The food packaging material with low water vapor permeability according to claim 5, characterized in that, The method for preparing the food packaging material includes the following steps: According to the formula, modified polyamide B, filler and antioxidant are melt-extruded and granulated at 210-230℃ to obtain modified masterbatch; According to the formula, polyamide, modified polyamide A, modified masterbatch, polyether ester elastomer and compatibilizer are mixed evenly, melt extruded at 240-260℃, and blown into film to obtain food packaging material.

7. A method for preparing a food packaging material with low water vapor permeability as described in any one of claims 1-6, Its features are, Includes the following steps: According to the formula, modified polyamide B, filler and antioxidant are melt-extruded and granulated at 210-230℃ to obtain modified masterbatch; According to the formula, polyamide, modified polyamide A, modified masterbatch, polyether ester elastomer and compatibilizer are mixed evenly, melt extruded at 240-260℃, and blown into film to obtain food packaging material.

8. The application of a food packaging material with low water vapor permeability as described in any one of claims 1-6 or a food packaging material prepared by the method described in claim 7 in the packaging of pre-prepared foods.

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