A food packaging bag and a method of manufacturing the same

Abstract

The application provides a food packaging bag and a preparation method thereof. The food packaging bag comprises the following raw materials in mass parts: 50 parts of polylactic acid, 50-100 parts of polybutylene adipate terephthalate, 5-10 parts of a plasticizer, and 5-10 parts of a modified filler; wherein the modified filler comprises a multi-arm grafted filler, the end group of the arm is an acyl chloride group, and the arm comprises a polyethylene glycol segment. The food packaging bag uses polylactic acid and polybutylene adipate terephthalate as main materials, further reduces the brittleness and improves the flexibility of the food packaging bag by using the plasticizer, and in addition, by adding the modified filler comprising the multi-arm grafted filler, the multi-arm grafted filler can improve the barrier property of the food packaging bag without deteriorating the flexibility of the food packaging bag, so that the obtained food packaging bag has good flexibility and barrier property.

Description

Technical Field

[0001] This application relates to the field of food packaging materials technology, specifically to a food packaging bag and its preparation method. Background Technology

[0002] With increasing environmental awareness and the popularization of sustainable development concepts, biodegradable materials are gradually becoming alternatives to traditional plastics. Among many biodegradable plastics, polylactic acid (PLA) is increasingly being widely used in the food packaging field due to its renewable resource origin, good biodegradability, and non-toxicity. However, as a thermoplastic, PLA faces some challenges in its application, especially in the food packaging sector.

[0003] Polylactic acid (PLA) has poor flexibility, especially at low temperatures where it is prone to embrittlement. Due to its high glass transition temperature, PLA exhibits high rigidity and low toughness at room temperature, making it susceptible to breakage or tearing in practical applications, thus affecting its effectiveness in food packaging. Furthermore, PLA has limited barrier properties, particularly poor barrier properties against water vapor and oxygen. Food packaging materials require high gas barrier properties to effectively extend shelf life and prevent the penetration of moisture and oxygen. However, due to its structural characteristics, PLA has poor barrier properties against these gases, making it unsuitable for packaging foods in high humidity or requiring long shelf lives.

[0004] Therefore, when using polylactic acid (PLA) to prepare food packaging bags, the PLA material needs to be modified accordingly to improve its flexibility and barrier properties, so that it can be suitable for the food packaging field.

[0005] Patent CN117799272A discloses a bio-based food packaging bag and its preparation method. The bio-based food packaging bag comprises the following components by weight: the outer layer comprises 100 parts PLA and 5-25 parts silicate; the middle layer comprises 100 parts PLA, 5-25 parts silicate, and 2-5 parts 2-methoxycinnamicaldehyde; and the inner layer comprises 100 parts PLA, 5-25 parts silicate, and 2-5 parts 2-methoxycinnamicaldehyde. This patent improves the gas barrier properties of PLA by adding silicate to form a blend; and improves the compatibility between PLA and silicate by adding 2-methoxycinnamicaldehyde, thereby enhancing the toughness of the bio-based food packaging bag.

[0006] The aforementioned patent improves the toughness and barrier properties of bio-based food packaging bags through a multi-layer design and the modification of PLA materials using silicates and 2-methoxycinnamic acid. The problem is that it primarily enhances the barrier properties of bio-based food packaging bags through a multi-layer design, with minimal impact on the material's inherent barrier properties. Furthermore, the multi-layer design increases the production cost of the food packaging bags.

[0007] Therefore, there is a need to provide a food packaging bag with good barrier properties. Summary of the Invention

[0008] This application provides a food packaging bag and a method for preparing the same. The food packaging bag has good barrier properties and flexibility by optimizing the composition of the raw materials.

[0009] In a first aspect, this application provides a food packaging bag comprising the following parts by weight of raw materials:

[0010] 50 parts polylactic acid, 50-100 parts poly(butylene adipate / terephthalate), 5-10 parts plasticizer, and 5-10 parts modified filler; wherein the modified filler includes multi-arm grafted filler, the end groups of the arms are acyl chloride groups, and the arms include polyethylene glycol segments.

[0011] According to this application, the food packaging bag uses polylactic acid and polybutylene adipate / terephthalate (PBAT) as the main materials. PBAT is also a biodegradable polymer material and will not affect the biodegradability of the food packaging bag. It also has good flexibility and a low glass transition temperature, and good compatibility with polylactic acid. Therefore, using these two materials as the main materials can effectively improve the flexibility of the food packaging bag. Furthermore, the use of plasticizers further reduces the brittleness of the food packaging bag and improves its flexibility. In addition, by adding modified fillers including multi-arm grafted fillers, whose arms are polyethylene glycol segments with acyl chloride end groups, the multi-arm grafted fillers can improve the barrier properties of the food packaging bag without deteriorating its flexibility. Thus, the resulting food packaging bag has both good flexibility and barrier properties.

[0012] In some embodiments, the raw materials include the following parts by weight:

[0013] 50 parts polylactic acid, 50-75 parts poly(butylene adipate / terephthalate), 5-8 parts plasticizer, and 5-8 parts modified filler.

[0014] In some embodiments, the preparation method of the multi-arm grafted filler includes the following steps:

[0015] S1: Polyethylene glycol with a weight-average molecular weight of 300-1000 is reacted with succinic anhydride in toluene, so that the hydroxyl groups at both ends of polyethylene glycol react with succinic anhydride, and carboxyl groups are grafted onto both ends of polyethylene glycol to obtain carboxylated polyethylene glycol.

[0016] S2: Carboxylated polyethylene glycol is reacted with thionyl chloride in toluene to react the carboxyl groups at both ends of the carboxylated polyethylene glycol with thionyl chloride, and acyl chloride groups are grafted onto both ends of the carboxylated polyethylene glycol to obtain acyl chloride polyethylene glycol.

[0017] S3: The filler is reacted with an aminosilane coupling agent in an ethanol-water solution to graft amino-containing branches onto the surface of the filler, thereby obtaining an amino-modified filler; the aminosilane coupling agent includes N-phenyl-γ-aminopropyltrimethoxysilane.

[0018] S4: The acyl chloride polyethylene glycol is reacted with the aminated filler in toluene, wherein the amino groups on the surface of the modified filler react with the acyl chloride polyethylene glycol to graft the acyl chloride polyethylene glycol onto the filler surface, thereby obtaining a multi-arm grafted filler.

[0019] In some implementations, S1 specifically includes:

[0020] Ten parts by mass of polyethylene glycol with a weight average molecular weight of 300-1000 and five to ten parts by mass of succinic anhydride were dispersed in 150-300 parts by mass of toluene and reacted at 60-80°C for 5-12 hours to obtain carboxylated polyethylene glycol.

[0021] In some implementations, S2 specifically includes:

[0022] 10 parts by mass of carboxylated polyethylene glycol and 10-30 parts by mass of thionyl chloride are dispersed in 100-200 parts by mass of toluene and reacted at 75-90°C for 18-36 h to obtain acyl-chlorinated polyethylene glycol.

[0023] In some implementations, S3 specifically includes:

[0024] Five parts by mass of filler and 40-60 parts by mass of aminosilane coupling agent are dispersed in 200-300 parts by mass of ethanol aqueous solution and reacted at 75-90℃ for 0.5-2 hours to obtain aminated filler.

[0025] In some embodiments, the filler comprises graphene oxide and carbon nanotubes, wherein the mass ratio of graphene oxide to carbon nanotubes is 1:0.1 to 0.5.

[0026] In some implementations, S4 specifically includes:

[0027] Ten parts by mass of acyl chloride polyethylene glycol and 1-5 parts by mass of the aminated filler are dispersed in 100-200 parts by mass of toluene and reacted at 80-90°C for 6-12 hours to obtain a multi-arm grafted filler.

[0028] In some embodiments, the polylactic acid has a weight-average molecular weight of 100,000 to 200,000.

[0029] In some embodiments, the weight-average molecular weight of the poly(butylene adipate / terephthalate) is 150,000 to 300,000.

[0030] In some embodiments, the plasticizer includes at least one of triacetyl citrate, tributyl citrate, triethyl citrate, polybutylene adipate, and epoxidized soybean oil.

[0031] In some embodiments, 0.5 to 2 parts of an antioxidant are also included; the antioxidant includes at least one of 2,6-di-tert-butyl-p-cresol, dilauryl thiopropionate, and vitamin E.

[0032] Secondly, this application provides a method for preparing food packaging bags, comprising:

[0033] Provide raw materials for food packaging bags according to any embodiment of the first aspect;

[0034] The raw materials are dried, melt-blended, extruded, granulated, and blow-molded to obtain food packaging bags.

[0035] According to this application, since it is prepared by using the raw materials in the food packaging bag described in any embodiment of the first aspect, it has the beneficial effects of the first aspect. Detailed Implementation

[0036] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0037] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] This application provides a food packaging bag and a method for preparing the same. By optimizing its raw material composition, the food packaging bag exhibits good flexibility and barrier properties. The specific embodiments provided in this application are described in detail below.

[0040] In a first aspect, this application provides a food packaging bag comprising the following parts by weight of raw materials:

[0041] 50 parts polylactic acid, 50-100 parts poly(butylene adipate / terephthalate), 5-10 parts plasticizer, and 5-10 parts modified filler; wherein the modified filler includes multi-arm grafted filler, the end groups of the arms are acyl chloride groups, and the arms include polyethylene glycol segments.

[0042] According to this application, the food packaging bag uses polylactic acid and polybutylene adipate terephthalate (PBAT) as the main materials. PBAT is also a biodegradable polymer material and will not affect the biodegradability of the food packaging bag. It also has good flexibility and a low glass transition temperature, and good compatibility with polylactic acid. Therefore, using these two materials as the main materials can effectively improve the flexibility of the food packaging bag. Furthermore, the use of plasticizers further reduces the brittleness of the food packaging bag and improves its flexibility. In addition, by adding a modified filler including multi-arm grafted fillers, where the end groups of the arms are reactive acyl chloride groups and the arms include polyethylene glycol segments, the multi-arm grafted filler can improve the barrier properties of the food packaging bag without deteriorating its flexibility. Therefore, the resulting food packaging bag has both good flexibility and barrier properties.

[0043] Specifically, in related technologies, by adding fillers to food packaging bags, the fillers can improve the crystallinity of the main material through heterogeneous nucleation during melt extrusion, thereby enhancing the barrier properties of the food packaging bags. However, increased crystallinity deteriorates the flexibility of the food packaging bags, making it impossible for them to simultaneously achieve good flexibility and barrier properties. Based on this, the inventors have prepared a multi-arm grafted filler. This multi-arm grafted filler consists of multiple reactive arms grafted in a star shape onto the filler surface. The end groups of the arms are acyl chloride groups, which exhibit good reactivity with the end groups (hydroxyl and / or carboxyl groups) of PLA and PBAT. During melt blending, the multi-arm grafted filler can utilize its reactivity, serving as a crosslinking center. Increasing the crosslinking density of the main material, combined with the physical barrier effect in the filler system, and extending the gas diffusion path can effectively improve the barrier performance of food packaging bags. Simultaneously, the inventors discovered that increasing the crosslinking density also reduces the flexibility of the food packaging bag. Grafting polyethylene glycol segments onto the arms can effectively reduce the impact of multi-arm grafted fillers on the flexibility of the food packaging bag. This is likely because in the crosslinking product between the multi-arm grafted filler and the main material, the filler and the main material are connected through arms, and the polyethylene glycol segments on the arms can effectively disperse the stress on the food packaging bag, thereby effectively reducing the impact of the multi-arm grafted filler as a crosslinking center on the flexibility of the food packaging bag. The resulting food packaging bag balances good flexibility and barrier performance.

[0044] In some embodiments, the raw materials include the following parts by weight:

[0045] 50 parts polylactic acid, 50-75 parts poly(butylene adipate / terephthalate), 5-8 parts plasticizer, and 5-8 parts modified filler.

[0046] In some of the above embodiments, by further optimizing the content of each component of the raw materials, the resulting food packaging bags have better flexibility and barrier properties.

[0047] In some embodiments, the preparation method of multi-arm grafted filler includes the following steps:

[0048] S1: Polyethylene glycol with a weight-average molecular weight of 300-1000 is reacted with succinic anhydride in toluene, so that the hydroxyl groups at both ends of polyethylene glycol react with succinic anhydride, and carboxyl groups are grafted onto both ends of polyethylene glycol to obtain carboxylated polyethylene glycol.

[0049] S2: Carboxylated polyethylene glycol is reacted with thionyl chloride in toluene to react the carboxyl groups at both ends of the carboxylated polyethylene glycol with thionyl chloride, and acyl chloride groups are grafted onto both ends of the carboxylated polyethylene glycol to obtain acyl chloride polyethylene glycol.

[0050] S3: The filler is reacted with an aminosilane coupling agent in an ethanol-water solution to graft amino-containing branches onto the surface of the filler, thus obtaining an amino-modified filler; the aminosilane coupling agent includes N-phenyl-γ-aminopropyltrimethoxysilane.

[0051] S4: The acyl chloride polyethylene glycol is reacted with the aminated filler in toluene, wherein the amino groups on the surface of the modified filler react with the acyl chloride polyethylene glycol to graft the acyl chloride polyethylene glycol onto the filler surface, thereby obtaining a multi-arm grafted filler.

[0052] In some of the above embodiments, the multi-arm grafted filler is obtained by the above preparation method. Specifically, in step S1, polyethylene glycol with a weight-average molecular weight of 300-1000 is modified by end-group carboxylation with succinic anhydride. The inventors have found that the weight-average molecular weight of polyethylene glycol has a certain influence on the flexibility and barrier properties of food packaging bags. When the weight-average molecular weight is within the above range, an appropriate chain length can effectively improve the compatibility of the multi-arm grafted filler, thereby making the multi-arm grafted filler easier to disperse uniformly and increasing the crosslinking density more uniformly in the system, thereby improving the flexibility and barrier properties. On the other hand, it can also reduce the influence of excessively long polyethylene glycol segments on the crosslinking density. Preferably, the weight-average molecular weight of polyethylene glycol in step S1 is 400-600.

[0053] In step S2, thionyl chloride is further used to modify the carboxylated polyethylene glycol by end-group acyl chloride, so that acyl chloride groups are grafted to both ends of the polyethylene glycol chain segments, thereby giving it good reactivity with hydroxyl and carboxyl groups.

[0054] In step S3, amino-containing branches are grafted onto the surface of the filler using an aminosilane coupling agent to obtain an aminated filler; wherein the aminosilane coupling agent includes N-phenyl-γ-aminopropyltrimethoxysilane; the inventors have discovered that by using an aminosilane coupling agent to graft amino-containing branches onto the surface of the filler, the residues after hydrolysis of the aminosilane coupling agent also act as branches on the surface of the filler. The use of different aminosilane coupling agents to obtain multi-arm grafted fillers has a certain impact on the performance of food packaging bags. When N-phenyl-γ-aminopropyltrimethoxysilane is used as the aminosilane coupling agent, the food packaging bag exhibits better barrier properties; the reason for this may be... The key advantage lies in the fact that the residues grafted onto the filler surface by N-phenyl-γ-aminopropyltrimethoxysilane exhibit stronger rigidity and hydrophobicity compared to other aminosilane coupling agents, such as γ-aminopropyltrimethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane. The presence of hydrophobic residues near the filler surface can increase the crystallization rate as a heterogeneous nucleus, reduce the free energy required to form a critical nucleus, thereby increasing crystallinity and further improving the barrier properties of food packaging bags. Furthermore, since polyethylene glycol segments are subsequently grafted, these residues do not affect the dispersibility of the multi-arm grafted filler in the system and have minimal impact on the flexibility of the food packaging bags.

[0055] In step S4, acyl chloride polyethylene glycol is used to graft and modify the aminated filler, so that polyethylene glycol segments with acyl chloride end groups are grafted onto the surface of the filler. It can be understood that after the acyl chloride polyethylene glycol reacts with the aminated filler, due to steric hindrance, the acyl chloride groups grafted onto the surface of the filler are difficult to react further with the unreacted amino groups on the surface of other fillers. Therefore, the fillers are not prone to agglomeration and cross-linking, and the resulting multi-arm grafted filler has better dispersibility and reactivity.

[0056] It should be noted that, unless otherwise specified, the amino groups mentioned in this application include primary and secondary amino groups that are reactive with acyl chloride groups.

[0057] In some implementations, S1 specifically includes:

[0058] Ten parts by mass of polyethylene glycol with a weight average molecular weight of 300-1000 and five to ten parts by mass of succinic anhydride were dispersed in 150-300 parts by mass of toluene, and the mixture was reacted at 60-80°C for 5-12 hours to obtain carboxylated polyethylene glycol. Based on the above embodiments, under the above conditions, the hydroxyl groups at both ends of polyethylene glycol can react with succinic anhydride to obtain carboxylated polyethylene glycol.

[0059] In some implementations, S2 specifically includes:

[0060] Ten parts by mass of carboxylated polyethylene glycol and 10-30 parts by mass of thionyl chloride were dispersed in 100-200 parts by mass of toluene and reacted at 75-90°C for 18-36 hours to obtain acyl-chlorinated polyethylene glycol. Based on the above embodiments, under the above conditions, the carboxyl groups at both ends of the carboxylated polyethylene glycol can react with thionyl chloride to obtain acyl-chlorinated polyethylene glycol.

[0061] In some implementations, S3 specifically includes:

[0062] Five parts by mass of filler and 40-60 parts by mass of aminosilane coupling agent are dispersed in 200-300 parts by mass of ethanol aqueous solution and reacted at 75-90℃ for 0.5-2 hours to obtain aminated filler.

[0063] In some of the above embodiments, under the above conditions, amino-containing side chains can be fully grafted onto the surface of the filler to obtain an aminated filler.

[0064] In some embodiments, the filler includes at least one of nano-calcium carbonate, graphene oxide, and carbon nanotubes.

[0065] It is understood that graphene oxide and carbon nanotube oxide have the meaning known in the art, namely, graphene and carbon nanotubes that have undergone oxidation treatment, the surface of which may include hydroxyl and / or carboxyl groups. For example, carbon nanotube oxide includes, but is not limited to, hydroxylated carbon nanotubes or carboxylated carbon nanotubes.

[0066] In some embodiments, the filler includes graphene oxide and carbon nanotubes, with a mass ratio of graphene oxide to carbon nanotubes of 1:0.1 to 0.5.

[0067] In some of the above embodiments, the inventors found that when the filler includes graphene oxide and carbon nanotubes in the above mass ratio, the resulting food packaging bag has better barrier properties. The possible reason is that by using the above composite filler, graphene oxide and carbon nanotubes act as crosslinking centers in the system to crosslink the main material. The two-dimensional graphene oxide and one-dimensional carbon nanotubes form a complex spatial network structure in the system, which can further reduce the diffusion of moisture and gas in the food packaging bag, thereby further improving the barrier properties of the food packaging bag.

[0068] In some implementations, S4 specifically includes:

[0069] Ten parts by mass of acyl chloride polyethylene glycol and 1-5 parts by mass of aminated filler are dispersed in 100-200 parts by mass of toluene and reacted at 80-90℃ for 6-12 hours to obtain multi-arm grafted filler.

[0070] In some of the above embodiments, under the above conditions, acyl chloride polyethylene glycol can fully graft acyl chloride polyethylene glycol segments onto the surface of the aminated filler, while further reducing the cross-linking between fillers caused by acyl chloride polyethylene glycol, thereby obtaining multi-arm grafted fillers with better dispersibility and reactivity, thus giving the resulting food packaging bags good flexibility and barrier properties.

[0071] In some embodiments, the weight-average molecular weight of polylactic acid (PLA) is 100,000 to 200,000. Based on the above embodiments, PLA with the above-mentioned weight-average molecular weight can better balance flexibility and biodegradability. As an example, in one embodiment of this application, PLA with a weight-average molecular weight of 150,000 is used.

[0072] In some embodiments, the weight-average molecular weight of polybutylene adipate (PBA) is 150,000 to 300,000. Based on the above embodiments, PBA with the above-mentioned weight-average molecular weight can give food packaging bags better flexibility. As an example, in one embodiment of this application, PBA with a weight-average molecular weight of 200,000 is used.

[0073] In some embodiments, the plasticizer includes at least one selected from triacetyl citrate, tributyl citrate, triethyl citrate, polybutylene adipate, and epoxidized soybean oil. As an example, triacetyl citrate is used as a plasticizer in one embodiment of this application.

[0074] In some embodiments, 0.5 to 2 parts of an antioxidant are also included; the antioxidant includes at least one selected from 2,6-di-tert-butyl-p-cresol, dilauryl thiopropionate, and vitamin E. Based on the above embodiments, further addition of antioxidants can reduce the oxidative decomposition of the main material and improve the service life of the food packaging bag. As an example, 2,6-di-tert-butyl-p-cresol is used as an antioxidant in one embodiment of this application.

[0075] Secondly, this application provides a method for preparing food packaging bags, comprising:

[0076] Provide raw materials for food packaging bags according to any embodiment of the first aspect;

[0077] After the raw materials are dried, they are melt-blended, extruded, granulated, and blow-molded to obtain food packaging bags.

[0078] According to this application, since it is prepared by using raw materials in a food packaging bag according to any embodiment of the first aspect, it has the beneficial effects of the first aspect.

[0079] In some embodiments, the process specifically includes: drying 50 parts of polylactic acid, 50-100 parts of poly(butylene adipate / terephthalate), and 5-10 parts of modified filler, then adding 5-10 parts of plasticizer and 0.5-2 parts of antioxidant and dispersing them evenly, extruding and granulating them using a twin-screw extruder, and blow molding them to obtain a food packaging bag.

[0080] In some embodiments, the feed zone temperature of the twin-screw extruder is 140–150°C, the melting zone temperature is 160–180°C, the homogenization zone temperature is 180–190°C, the extrusion zone temperature is 170–180°C, and the screw shear rate is 20–60 rpm.

[0081] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0082] The graphene oxide was a carboxyl-based graphene purchased from Jiangsu Xianfeng Nanomaterials, with a thickness of 0.8–1.2 nm and a carboxyl content of approximately 5 wt%.

[0083] Carbon nanotubes, specifically carboxylated multi-walled carbon nanotubes purchased from Jiangsu Xianfeng Nanomaterials, have a diameter of 10–20 nm, an inner diameter of 5–10 nm, a length of 0.5–2 μm, and a carboxyl content of 2 wt%.

[0084] Example 1

[0085] Preparation of food packaging bags:

[0086] 50 parts by weight of polylactic acid with a weight average molecular weight of 150,000, 70 parts by weight of polybutylene adipate / terephthalate with a weight average molecular weight of 200,000, and 6 parts by weight of multi-arm grafted filler were dried, and then 8 parts by weight of triacetyl citrate and 1 part by weight of 2,6-di-tert-butyl-p-cresol were added and uniformly dispersed. The mixture was then extruded and granulated using a twin-screw extruder and blow-molded to obtain a food packaging bag.

[0087] The multi-arm grafted filler was prepared by the following method:

[0088] 10 parts by mass of polyethylene glycol with a weight average molecular weight of 400 and 6 parts by mass of succinic anhydride were dissolved in 200 parts by mass of toluene. The mixture was heated at 75°C for 9 hours. After extraction with chloroform, the mixture was dried. After removing chloroform by rotary evaporation, the mixture was dissolved in diethyl ether and dried to obtain carboxylated polyethylene glycol.

[0089] 10 parts by mass of carboxylated polyethylene glycol and 20 parts by mass of thionyl chloride were dissolved in 150 parts by mass of toluene, and the mixture was heated at 85°C for 24 h. The mixture was then dried by rotary evaporation to obtain acyl chloride polyethylene glycol.

[0090] Five parts by mass of the filler were ultrasonically dispersed in 200 parts by mass of an aqueous ethanol solution (ethanol to water volume ratio of 1:1), and then 50 parts by mass of N-phenyl-γ-aminopropyltrimethoxysilane were added. The mixture was heated at 85°C for 1 hour. After the reaction was completed, the mixture was centrifuged, washed and dried to obtain the aminated filler.

[0091] 10 parts by mass of acyl chloride polyethylene glycol and 4 parts by mass of aminated filler were dispersed in 150 parts by mass of toluene, ultrasonically dispersed for 15 min, heated at 85℃ for 8 h, and centrifuged and dried to obtain multi-arm grafted filler.

[0092] The filler is a mixture of graphene oxide and carbon nanotubes in a mass ratio of 1:0.2.

[0093] Example 2

[0094] Preparation of food packaging bags:

[0095] It is largely the same as Example 1, except that the filler used in the preparation of the multi-arm grafted filler is graphene oxide.

[0096] Example 3

[0097] Preparation of food packaging bags:

[0098] Similar to Example 1, except that the filler used in the preparation of the multi-arm grafted filler is carbon oxide nanotube.

[0099] Example 4

[0100] Preparation of food packaging bags:

[0101] Similar to Example 1, except that polyethylene glycol with a weight-average molecular weight of 600 was used in the preparation of the multi-arm grafted filler.

[0102] Example 5

[0103] Preparation of food packaging bags:

[0104] Similar to Example 1, except that polyethylene glycol with a weight-average molecular weight of 300 was used in the preparation of the multi-arm grafted filler.

[0105] Example 6

[0106] Preparation of food packaging bags:

[0107] Similar to Example 1, except that polyethylene glycol with a weight-average molecular weight of 1000 was used in the preparation of the multi-arm grafted filler.

[0108] Example 7

[0109] Preparation of food packaging bags:

[0110] Similar to Example 1, except that γ-aminopropyltrimethoxysilane is used as an aminosilane coupling agent in the preparation of the multi-arm grafted filler.

[0111] Example 8

[0112] Preparation of food packaging bags:

[0113] Similar to Example 1, except that N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was used as an aminosilane coupling agent in the preparation of the multi-arm grafted filler.

[0114] Example 9

[0115] Similar to Example 1, except that the multi-arm grafted filler is prepared by the following method:

[0116] 10 parts by mass of polyethylene glycol with a weight average molecular weight of 400 and 6 parts by mass of succinic anhydride were dissolved in 200 parts by mass of toluene. The mixture was heated at 75°C for 9 hours. After extraction with chloroform, the mixture was dried. After removing chloroform by rotary evaporation, the mixture was dissolved in diethyl ether and dried to obtain carboxylated polyethylene glycol.

[0117] 10 parts by mass of carboxylated polyethylene glycol and 20 parts by mass of thionyl chloride were dissolved in 150 parts by mass of toluene, and the mixture was heated at 85°C for 24 h. The mixture was then dried by rotary evaporation to obtain acyl chloride polyethylene glycol.

[0118] 10 parts by mass of acyl chloride polyethylene glycol and 4 parts by mass of filler were ultrasonically dispersed in 150 parts by mass of toluene. The ultrasonic dispersion was carried out for 15 min, and the reaction was carried out at 85℃ for 8 h. The multi-arm grafted filler was obtained by centrifugation and drying.

[0119] The filler is a mixture of graphene oxide and carbon nanotubes in a mass ratio of 1:0.2.

[0120] Comparative Example 1

[0121] Preparation of food packaging bags:

[0122] 50 parts by weight of polylactic acid with a weight average molecular weight of 150,000, 70 parts by weight of polybutylene adipate with a weight average molecular weight of 200,000, and 6 parts by weight of acyl-chlorographene were dried. Then, 5 parts by weight of polyethylene glycol with a weight average molecular weight of 400, 8 parts by weight of triacetyl citrate, and 1 part by weight of 2,6-di-tert-butyl-p-cresol were added and uniformly dispersed. The mixture was then extruded and granulated using a twin-screw extruder and blow-molded to obtain a food packaging bag.

[0123] The acyl-chlorographene is prepared by the following method:

[0124] Ten parts by mass of graphene oxide were ultrasonically dispersed in 200 parts by mass of toluene, and then 20 parts by mass of thionyl chloride were added. The mixture was heated at 85°C for 24 hours, centrifuged, and dried to obtain acyl-chromium graphene.

[0125] Test section

[0126] The oxygen permeability (OT value) of the food packaging bags obtained in the above examples and comparative examples was determined according to GB / T 1038-2022 "Test method for gas permeability of plastic articles, films and sheets - differential pressure method"; the maximum tensile stress was determined according to GB / T 1040-2006 "Determination of tensile properties of plastics"; the results are shown in Table 1.

[0127] Table 1

[0128] <![CDATA[OT value [cm 3 / (m 2 ·d·Pa)]]]> Maximum tensile stress / N Example 1 632 60.7 Example 2 696 55.3 Example 3 719 52.9 Example 4 641 61.2 Example 5 677 54.4 Example 6 698 58.6 Example 7 703 61.1 Example 8 689 60.3 Example 9 722 60.9 Comparative Example 1 843 45.2

[0129] According to Table 1, the food packaging bags obtained in each embodiment have smaller OT values ​​and larger maximum tensile stresses compared to the comparative example, indicating that the food packaging bags obtained in this application have better barrier properties and flexibility. The reason may be that the filler used in Comparative Example 1 has poor compatibility with the main material. Although it is reactive with the main material, due to poor compatibility, it cannot uniformly increase the crosslinking density of the material. The addition of polyethylene glycol cannot effectively improve the compatibility of the filler, resulting in poor barrier properties and flexibility of the obtained food packaging bags.

[0130] As shown in Examples 1-3, the multi-arm grafted fillers obtained by using different fillers have a certain impact on the barrier properties and flexibility of food packaging bags. Among them, the multi-arm grafted fillers modified by using a certain proportion of graphene oxide and carbon nanotubes as fillers have better barrier properties and flexibility than the food packaging bags obtained by using single fillers in Examples 2 and 3. The reason may be that the more complex three-dimensional structure formed by two-dimensional graphene oxide and one-dimensional carbon nanotubes in the system can further improve its flexibility and further reduce oxygen permeation in the material, thereby further improving its barrier properties. In addition, the multi-arm grafted filler obtained by using graphene oxide in Example 3 is better than that in Example 2.

[0131] As shown in Examples 1, 4-6, the length of the polyethylene glycol segments on the surface of the multi-arm grafted filler also has a certain impact on the barrier properties and flexibility of the food packaging bag. Examples 1 and 4 exhibit better barrier properties and flexibility. This may be because the shorter polyethylene glycol segments in Example 5 may affect its dispersibility, thus affecting the barrier properties and flexibility of the food packaging bag; while the longer polyethylene glycol segments in Example 6 may affect the crosslinking density of the material, thus affecting the barrier properties and flexibility of the food packaging bag. Therefore, in the preparation of the multi-arm grafted filler, using polyethylene glycol with a weight-average molecular weight of 400-600 results in food packaging bags with better barrier properties and flexibility.

[0132] As shown in Examples 1 and 7-9, the use of different types of aminosilane coupling agents or the absence of aminosilane coupling agents in multi-arm grafted fillers have a certain impact on the barrier properties and flexibility of food packaging bags. It can be seen that the flexibility of food packaging bags obtained in Examples 1 and 7-9 is relatively similar, but the barrier properties of the food packaging bag obtained in Example 1 are significantly better than those in other examples. This indicates that in the preparation process of multi-arm grafted fillers, using N-phenyl-γ-aminopropyltrimethoxysilane to modify the filler before further grafting results in better barrier properties of the food packaging bag without significantly deteriorating its flexibility.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A food packaging bag, characterized by, The food packaging bag comprises the following raw materials in parts by mass: 50 parts of polylactic acid, 50-100 parts of polybutylene adipate terephthalate, 5-10 parts of plasticizer, and 5-10 parts of modified filler. The modified filler comprises a multi-arm grafted filler, the end groups of the arms are acyl chloride groups, and the arms comprise polyethylene glycol segments. The preparation method of the multi-arm grafted filler comprises the following steps: S1: reacting polyethylene glycol with a weight average molecular weight of 300-1000 and succinic anhydride in toluene, reacting the hydroxyl groups at both ends of the polyethylene glycol with the succinic anhydride, grafting carboxyl groups at both ends of the polyethylene glycol, and obtaining carboxylated polyethylene glycol; S2: reacting the carboxylated polyethylene glycol with thionyl chloride in toluene, reacting the carboxyl groups at both ends of the carboxylated polyethylene glycol with the thionyl chloride, grafting acyl chloride groups at both ends of the carboxylated polyethylene glycol, and obtaining acyl chloride polyethylene glycol; S3: reacting the filler with an amino silane coupling agent in an aqueous ethanol solution, grafting amino-containing branched chains on the surface of the filler, and obtaining an aminated filler; the amino silane coupling agent comprises N-phenyl-γ-aminopropyl trimethoxysilane; S4: reacting the acyl chloride polyethylene glycol with the aminated filler in toluene, wherein the amino groups on the surface of the modified filler react with the acyl chloride polyethylene glycol, grafting the acyl chloride polyethylene glycol on the surface of the filler, and obtaining a multi-arm grafted filler.

2. The food packaging bag of claim 1, wherein The food packaging bag comprises the following raw materials in parts by mass: 50 parts of polylactic acid, 50-100 parts of polybutylene adipate terephthalate, 5-10 parts of plasticizer, and 5-10 parts of modified filler.

3. The food packaging bag of claim 1, wherein The S1 specifically comprises: dispersing 10 parts by mass of polyethylene glycol with a weight average molecular weight of 300-1000 and 5-10 parts by mass of succinic anhydride in 150-300 parts by mass of toluene, reacting at 60-80°C for 5-12 hours, and obtaining carboxylated polyethylene glycol.

4. The food packaging bag of claim 1, wherein The S2 specifically comprises: dispersing 10 parts by mass of carboxylated polyethylene glycol and 10-30 parts by mass of thionyl chloride in 100-200 parts by mass of toluene, reacting at 75-90°C for 18-36 hours, and obtaining acyl chloride polyethylene glycol.

5. The food packaging bag of claim 1, wherein The S3 specifically comprises: dispersing 5 parts by mass of filler and 40-60 parts by mass of amino silane coupling agent in 200-300 parts by mass of aqueous ethanol, reacting at 75-90°C for 0.5-2 hours, and obtaining an aminated filler.

6. The food packaging bag according to claim 1 or 5, characterized in that, The filler comprises graphene oxide and oxidized carbon nanotubes, and the mass ratio of the graphene oxide to the oxidized carbon nanotubes is 1:0.1-0.

5.

7. The food packaging bag of claim 1, wherein The S4 specifically comprises: dispersing 10 parts by mass of acyl chloride polyethylene glycol and 1-5 parts by mass of the aminated filler in 100-200 parts by mass of toluene, reacting at 80-90°C for 6-12 hours, and obtaining a multi-arm grafted filler.

8. The food packaging bag according to claim 1 or 2, characterized in that, The food packaging bag satisfies at least one of the following conditions: 1) the weight average molecular weight of the polylactic acid is 100000-200000; 2) the weight average molecular weight of the polybutylene adipate terephthalate is 150000-300000; 3) the plasticizer comprises at least one of triacetyl glycerol citrate, tributyl citrate, triethyl citrate, polybutylene adipate, and epoxidized soybean oil; 4) further comprising 0.5-2 parts of an antioxidant; the antioxidant comprises at least one of 2,6-di-tert-butyl-p-cresol, dilaurylthiopropionate, vitamin E.

9. A method of making a food packaging bag, characterized by, Comprise: providing raw materials in the food packaging bag according to any one of claims 1-8; after drying the raw materials, melt blending extrusion, granulation, blow molding to obtain a food packaging bag.