Novel steaming-resistant high-barrier film

Abstract

The utility model discloses a novel steaming-resistant and boiling-resistant high-barrier film which comprises a base material layer, and an adhesion layer, a barrier coating and a cross-linking coating which are sequentially arranged on the base material layer, the base material layer takes PET (Polyethylene Terephthalate) or PA (Polyamide) high-molecular plastic as a base material, and the thickness is 6-100 microns; the adhesion layer is formed on the base material layer through corona treatment, and the thickness of the adhesion layer is 5-10 nm, so that the adhesion force of the base material layer and the barrier coating is improved; the barrier coating is formed by coating and curing a PCA coating and a water-based coating liquid, and the thickness of the barrier coating is 0.5-2 microns; the cross-linked coating is formed by coating and curing a multivalent organic metal compound, and the thickness of the cross-linked coating is 0.2-1 mu m. The special structure and material are matched, the barrier property can be further improved after water boiling or cooking, the whole structure is of an organic coating structure, and the bending resistance and rubbing resistance of the product are higher.

Description

Technical Field

[0001] This utility model relates to the field of retort packaging technology, and in particular to a novel retort-resistant high-barrier film. Background Technology

[0002] Typical retort-resistant transparent barrier films use PET or PA as the substrate and are manufactured through vacuum deposition of an inorganic oxide layer and precision coating of an organic layer. This requires the combined use of vacuum deposition equipment and processes, as well as precision coating processes and equipment. The general structure consists of an organic primer layer coated on the substrate, an inorganic oxide layer vacuum-deposited on the organic primer layer, and an organic protective layer coated on the inorganic oxide layer. This type of retort-resistant barrier film involves numerous equipment and processes. After boiling or steaming, the inorganic oxide and organic layers become less dense under high temperature and humidity conditions, significantly reducing their barrier properties against oxygen and moisture. Furthermore, because the inorganic oxide film is relatively brittle, its retort-resistant properties decrease significantly after bending and rubbing. Utility Model Content

[0003] The purpose of this invention is to provide a novel high-barrier membrane that is resistant to boiling.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] A novel high-barrier membrane resistant to boiling includes a substrate layer and an adhesion layer, a barrier coating, and a crosslinking coating sequentially layered on the substrate layer. The substrate layer is made of PET or PA polymer plastic with a thickness of 6–100 μm. The adhesion layer is formed by corona treatment on the substrate layer and has a thickness of 5–10 nm to improve adhesion between the substrate layer and the barrier coating. The barrier coating is formed by coating and curing PCA coating with an aqueous coating solution and has a thickness of 0.5–2 μm. The crosslinking coating is formed by coating and curing a polyvalent organometallic compound and has a thickness of 0.2–1 μm.

[0006] As a further technical solution of this utility model: the aqueous coating liquid is composed of water-soluble or water-dispersible polycarboxylic acids, polyols, and polyamines.

[0007] As a further technical solution of this utility model: the PCA coating contains polyacrylamide, polymethacrylamide or polyamine.

[0008] As a further technical solution of this utility model: the multivalent organometallic compound of the crosslinked coating is a polymer containing a divalent or higher metal compound.

[0009] As a further technical solution of this utility model: the barrier coating is processed by micro-recessed or slit coating, and the coating is cured by heating in an oven.

[0010] As a further technical solution of this utility model: the cross-linked coating is processed by micro-recessed or slit coating, and the coating is cured by heating in an oven. After coating, it is cured at 40-60℃ for 48-120 hours.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows: This utility model proposes a novel high-barrier film resistant to boiling. Through the combination of the substrate layer, the adhesion layer, the barrier coating and the cross-linking coating, its special structure and material combination further enhances the barrier properties after boiling or steaming. Moreover, its structure is entirely an organic coating structure, which makes the product more resistant to bending and rubbing. It can adsorb the odor of food contents after boiling and steaming by the polyvalent metals contained in the cross-linking coating. Its materials are composed of organic and inorganic oxides. After composite bag making, it can be microwave heated and is also convenient for scanning to detect whether there is metal residue in the packaging bag. Attached Figure Description

[0012] Figure 1 This is a layer structure diagram of a novel heat-resistant, high-barrier membrane. Detailed Implementation

[0013] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of protection of this utility model.

[0014] Please see Figure 1 A novel high-barrier film resistant to boiling is available for use in food packaging bags. It combines high barrier properties with flexibility, meeting the requirements for high barrier properties and reducing odors after boiling or steaming for food contents such as fish, beef, pork, and eggs containing large amounts of sulfur-containing amino acids.

[0015] The novel heat-resistant high-barrier film includes a substrate layer 10 and an adhesion layer 20, a barrier coating 30, and a crosslinking coating 40 sequentially layered on the substrate layer 10. The substrate layer 10 is made of PET or PA polymer plastic with a thickness of 6-100 μm. The adhesion layer 20 is formed by corona treatment on the substrate layer 10 and has a thickness of 5-10 nm. Corona treatment opens the molecular bonds on the surface of the polymer material, forming stronger intermolecular forces for the coating, thereby improving the adhesion between the substrate layer 10 and the barrier coating 30. The barrier coating 30 is formed by coating and curing PCA coating with an aqueous coating liquid and has a thickness of 0.5-2 μm. The crosslinking coating 40 is formed by coating and curing a polyvalent organometallic compound and has a thickness of 0.2-1 μm.

[0016] Furthermore, in this embodiment, the aqueous coating liquid is composed of water-soluble or water-dispersible polycarboxylic acids, polyols, or polyamines, preferably water-soluble.

[0017] Furthermore, in this embodiment, the polycarboxylic acid may be 1,2,3,4-butanetetracarboxylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymer, acrylic acid-maleic acid copolymer, ethylene-maleic acid copolymer, or other olefin maleic acid copolymers, polysaccharides with carboxyl groups on the side chains such as alginic acid, carboxyl-containing polyamides, polyesters, etc. It may contain one or more of the above-mentioned polycarboxylic acids. From the perspective of gas barrier properties, polyacrylic acid or olefin maleic acid copolymers are preferred, especially ethylene-maleic acid copolymer (EMA), wherein EMA is obtained by polymerizing maleic anhydride and ethylene through known methods such as solution free radical polymerization.

[0018] Furthermore, in this embodiment, the PCA coating contains polyacrylamide, polymethacrylamide, or polyamine. These substances react with PCA to further enhance the barrier properties. The dense molecular structure of polycarboxylic acid and the carboxyl groups in the molecules adsorb O2 and H2O molecules, thereby forming a barrier.

[0019] Furthermore, in this embodiment, the barrier coating 30 can be cured by using a micro-recessed or slit coating process and an oven heating process.

[0020] Furthermore, in this embodiment, the multivalent organometallic compound of the crosslinked coating 40 is a polymer containing a divalent or higher-valent metal compound. The metal is one or more organometallic compounds such as Zn, Mg, and Ca; the compound can be an oxide, hydroxide, or halide; inorganic salts such as carbonates, bicarbonates, phosphates, and sulfates; carboxylate salts such as acetates, formates, stearates, and maleates; and organic acid salts such as sulfonates, preferably oxides or carbonates. Magnesium salts such as magnesium oxide, magnesium carbonate, magnesium hydroxide, and magnesium acetate, as well as divalent metal compounds such as calcium carbonate, calcium acetate, zinc oxide, and zinc acetate, are preferred for better barrier properties. The metal compound is preferably in powder form, with an average particle size preferably of 0.01–2.0 μm, particularly preferably 0.05–1.0 μm. It exhibits good dispersibility, mechanical strength, and low haze. The metal compound can be further improved in terms of dispersibility, weather resistance, wettability with thermoplastic resins, heat resistance, and transparency through surface treatments such as inorganic or organic treatments. Inorganic treatments include alumina treatment, silica treatment, titanium dioxide treatment, and zirconium oxide treatment. Organic treatments can utilize fatty acid compounds, amine compounds such as pentaerythritol, triethanolamine, and tris(hydroxymethyl)amine, and organosilicon-based compounds such as organosilicon resins. The content of the metal compound is preferably 0.2–20% by mass, more preferably 0.2–5% by mass. The resulting barrier film product exhibits low haze and good barrier properties and mechanical strength.

[0021] Furthermore, in this embodiment, the crosslinked coating 40 can be cured by a micro-recessed or slit coating process using an oven heating process. After the coating process is completed, a curing process of 40-60℃ x 48H-120H is adopted to make the polymer reaction crosslinking of the coating more complete and stable. The organometallic compounds promote the further crosslinking of the PCA of the barrier coating 30 under water vapor and high temperature conditions, thereby improving the barrier performance after boiling or steaming. When food contents, especially meats such as fish, beef, and pork, as well as eggs containing a large amount of sulfur-containing amino acids, are boiled or steamed, hydrogen sulfide (H2S) or thiols (R-SH) will be released. Zn, Mg, and Ca polyvalent metals will absorb H2S and R-SH substances, thereby reducing the odor of the food after boiling or steaming.

[0022] Understandably, the method for manufacturing a novel retort-resistant high-barrier film according to this utility model is as follows: it can be prepared simply by coating a PET or PA substrate. The barrier layer is an organic coating with good flexibility. Due to its special structural design, during boiling or steaming, the polyvalent metals in this barrier film increase the cross-linking of PCA organic molecules due to the high temperature and moisture, thus improving the barrier performance of the product. Furthermore, because the polyvalent metals contained in the cross-linked coating 40 adsorb hydrogen sulfide (H2S) or thiols (R-SH) released from the food contents after cooking, food packaging bags made with this novel retort-resistant high-barrier film can also reduce odors inside the food packaging bags.

[0023] In summary, this novel high-barrier film for boiling and steaming, through the combination of the substrate layer 10, the adhesion layer 20, the barrier coating 30, and the cross-linking coating 40, has a special structure and material combination that further enhances its barrier properties after boiling or steaming. Moreover, its structure is entirely composed of organic coatings, resulting in stronger resistance to bending and rubbing. It can adsorb the odors of food contents after boiling and steaming by using the polyvalent metals contained in the cross-linking coating 40. Furthermore, since its materials are composed of organic and inorganic oxides, the composite bag can be microwaved and is also easy to scan to detect whether there are metal residues in the packaging bag.

[0024] Any combination of different embodiments of this utility model, provided it does not violate the inventive concept of this utility model, shall be considered as the disclosure of this utility model; any simple modifications to the technical solution and any combination of different embodiments within the scope of the inventive concept of this utility model, without violating the inventive concept of this utility model, shall be within the protection scope of this utility model.

Claims

1. A novel high-barrier membrane resistant to boiling, characterized in that: The material includes a substrate layer (10) and an adhesion layer (20), a barrier coating (30), and a crosslinking coating (40) sequentially layered on the substrate layer (10). The substrate layer (10) is made of PET or PA polymer plastic and has a thickness of 6 to 100 μm. The adhesion layer (20) is formed by corona treatment on the substrate layer (10) and has a thickness of 5 to 10 nm to improve the adhesion between the substrate layer (10) and the barrier coating (30). The barrier coating (30) is formed by coating and curing PCA coating with an aqueous coating liquid and has a thickness of 0.5 to 2 μm. The crosslinking coating (40) is formed by coating and curing a polyvalent organometallic compound and has a thickness of 0.2 to 1 μm.

2. The novel heat-resistant high-barrier membrane according to claim 1, characterized in that: The aqueous coating liquid is composed of water-soluble or water-dispersible polycarboxylic acids, polyols, and polyamines.

3. The novel heat-resistant high-barrier membrane according to claim 1, characterized in that: The PCA coating contains polyacrylamide, polymethacrylamide, or polyamine.

4. The novel heat-resistant high-barrier membrane according to claim 1, characterized in that: The cross-linked coating (40) is a polyvalent organometallic compound, which is a polymer containing a divalent or higher metal compound.

5. The novel heat-resistant high-barrier membrane according to claim 1, characterized in that: The barrier coating (30) is applied by micro-recessed or slotted coating and cured by oven heating.

6. The novel heat-resistant high-barrier membrane according to claim 1, characterized in that: The cross-linked coating (40) is processed by micro-recessed or slit coating, cured by heating in an oven, and then cured at 40-60℃ for 48-120 hours.

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