Sealing film with oxygen uptake effect, preparation method and application thereof and package

Abstract

The invention discloses a sealing film with an oxygen uptake effect and a preparation method, application and package thereof, and belongs to the technical field of food package. The sealing film comprises a film body and a functional coating, the functional coating contains noble metal capable of catalyzing hydrogen-oxygen reaction, the functional coating at least has an area satisfying E = c * h, E > = 150, h > = 2 and c > = 50, and h and c are the thickness value of the area and the concentration value of the noble metal respectively. The functional coating contains precious metal capable of catalyzing the hydrogen-oxygen reaction, can catalyze the hydrogen-oxygen reaction, and is beneficial to reducing the oxygen content; the coating can also solidify the generated water, and the generated water can open a gas migration channel in the functional coating, so that the removal of oxygen is further accelerated; the precious metal is embodied in the form of a coating, so that the risk of migration and falling of the precious metal in the goods shelf process can be reduced or avoided. The sealing film has an oxygen absorption effect and can be further used for various packages, such as food packages of dairy products and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of food packaging, in particular to a sealing film with oxygen absorption effect, a preparation method and application thereof, and a package. BACKGROUND

[0002] Traditional milk powder filling cannot completely remove oxygen in the tank due to process limitations, and the oxygen content can only be reduced to about 2% to 3%, and the presence of oxygen is not conducive to oxygen-sensitive formula ingredients, which can easily cause oxidation of oxygen-sensitive ingredients, resulting in poor product quality. In addition, milk powder is not only sensitive to oxygen, but also sensitive to water, which can manifest as clumping after milk powder is in contact with water.

[0003] In view of this, the present application is proposed. SUMMARY

[0004] The present application aims to provide a sealing film with oxygen absorption effect, a preparation method and application thereof, and a package, to solve or improve the above technical problems.

[0005] The present application can be achieved as follows:

[0006] In a first aspect, the present application provides a sealing film, which comprises a film body and a functional coating arranged on the surface of the film body; the functional coating contains noble metal capable of catalyzing hydrogen-oxygen reaction; the functional coating has at least a region satisfying E=c x h, E≥150, h≥2, c≥50; wherein the thickness value of the region is h in μm; the concentration value of the noble metal in the region is c in ppm.

[0007] In an optional embodiment, the sealing film is used to absorb oxygen by consuming oxygen in the package containing the sealing film under the cooperation of hydrogen.

[0008] In a second aspect, the present application provides a sealing film with oxygen absorption effect, which comprises a film body and a functional coating arranged on the surface of the film body; the functional coating contains noble metal capable of catalyzing hydrogen-oxygen reaction; the functional coating has at least a region satisfying E=c x h, E≥150, h≥2, c≥50; wherein the thickness value of the region is h in μm; the concentration value of the noble metal in the region is c in ppm.

[0009] The sealing film is used to consume oxygen in the package containing the sealing film under the cooperation of hydrogen.

[0010] In an optional embodiment, the sealing film in any of the above embodiments consumes oxygen in the package by hydrogen-oxygen reaction of hydrogen and oxygen under the catalytic action of the noble metal when the package contains both hydrogen and oxygen.

[0011] In an optional embodiment, the functional coating has a thickness value h in μm, and the noble metal has a concentration value c in ppm in the functional coating, c and h satisfy: E=c×h, E≥150, h≥2, and c≥50.

[0012] In an optional embodiment, the noble metal has at least one of the following characteristics:

[0013] Characteristic 1: the noble metal comprises at least one of Pd and Pt;

[0014] Characteristic 2: the noble metal has a particle size of 10 nm to 20 nm;

[0015] Characteristic 3: the noble metal has a concentration level of ppm in the functional coating.

[0016] In an optional embodiment, the functional coating has a thickness of 2 μm to 10 μm.

[0017] In an optional embodiment, the functional coating has a thickness of 5 μm to 7 μm.

[0018] In an optional embodiment, the sealing film further comprises a first heat-seal layer disposed on a surface of the film body, and the functional coating is disposed on a surface of the first heat-seal layer away from the film body.

[0019] In an optional embodiment, the sealing film further comprises a second heat-seal layer disposed on a surface of the functional coating away from the first heat-seal layer.

[0020] In an optional embodiment, the sealing film further comprises an additional layer disposed on a surface of the film body opposite to the first heat-seal layer.

[0021] In an optional embodiment, the additional layer comprises a varnish coating.

[0022] In an optional embodiment, the film body comprises an aluminum foil or a plastic film.

[0023] In an optional embodiment, the total thickness of the first heat-seal layer, the functional coating, and the second heat-seal layer is not more than 20 μm.

[0024] In a third aspect, the present application provides a method for preparing the sealing film according to the foregoing embodiments, comprising the following steps: disposing a structural layer on a surface of the film body at a predetermined position.

[0025] In an optional embodiment, the preparation slurry of each structural layer is coated at the predetermined position and dried.

[0026] In an optional embodiment, the preparation slurry of the functional coating comprises a noble metal dispersion liquid and an adhesive.

[0027] In an alternative embodiment, the mass ratio of the noble metal dispersion liquid to the adhesive is 80:20 to 90:10.

[0028] In an alternative embodiment, the concentration of the noble metal in the noble metal dispersion liquid is 500 ppm to 10,000 ppm.

[0029] In an alternative embodiment, the noble metal dispersion liquid is an organic solvent type noble metal dispersion liquid or a water type noble metal dispersion liquid, wherein the carrier in the organic solvent type noble metal dispersion liquid is mainly an organic reagent, and the carrier in the water type noble metal dispersion liquid is mainly water.

[0030] In an alternative embodiment, the coating amount of the functional coating is 2 g / m 2 to 10 g / m 2 , and / or the coating speed of the functional coating is 30 m / min to 100 m / min.

[0031] In an alternative embodiment, the drying temperature of the functional coating is 80°C to 130°C.

[0032] In a fourth aspect, the present application provides an application of the sealing film according to any one of the preceding embodiments, which is used for consuming oxygen in a package containing the sealing film.

[0033] In a fifth aspect, the present application provides a package, which comprises a package body, and the sealing film according to any one of the preceding embodiments is provided on the sealing end of the package body, or the package body is composed of the sealing film according to any one of the preceding embodiments.

[0034] In an alternative embodiment, the package body contains residual oxygen and a mixed gas comprising hydrogen and an inert gas.

[0035] In an alternative embodiment, after the package is sealed, the content of hydrogen in the package is at least 2 times the residual oxygen content in the package.

[0036] In an alternative embodiment, the material of the package body comprises a metal-containing material.

[0037] In an alternative embodiment, the metal-containing material comprises a material containing iron and / or aluminum.

[0038] In an alternative embodiment, the package body further contains oxygen-sensitive contents.

[0039] In an alternative embodiment, the contents comprise dairy products.

[0040] In an alternative embodiment, the contents comprise milk powder and / or protein powder.

[0041] The beneficial effects of the present application include:

[0042] The functional coating in the sealing film provided by this invention contains a noble metal capable of catalyzing the hydrogen-oxygen reaction, thus reducing oxygen content. This functional coating can also solidify the generated water, which opens gas migration channels within the coating, further accelerating oxygen removal. The functional coating has at least regions satisfying E = c × h, E ≥ 150, h ≥ 2, and c ≥ 50, achieving basic removal of oxygen and water. By incorporating the noble metal capable of catalyzing the hydrogen-oxygen reaction in the form of a coating, the risk of migration and shedding of the noble metal during shelf life can be reduced or avoided. The sealing film containing this functional coating has oxygen and water absorption effects and can be further used in various packaging applications, such as food packaging for milk powder. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the first structure of the sealing film provided by the present invention;

[0045] Figure 2 This is a schematic diagram of a second structure of the sealing film provided by the present invention;

[0046] Figure 3 This is a graph showing the residual oxygen content of the nine experimental groups in Experiment Example 1 of this invention at different numbers of days.

[0047] Figure 4 for Figure 3 The results of residual oxygen content for the "20-5", "15-5", and "10-5" experimental groups under different number of days are shown in the figure.

[0048] Figure 5 for Figure 3 The results of residual oxygen content in the "15-10" experimental group under different number of days are shown in the figure.

[0049] Figure 6 for Figure 3 The results of residual oxygen content for the "20-7", "15-7", and "10-7" experimental groups under different number of days are shown in the figure.

[0050] Figure 7 for Figure 3 The graph shows the results of residual oxygen content for different number of days in the experimental groups "15-5", "15-7" and "15-10".

[0051] Icon: 10-sealing film; 11-additional layer; 12-film body; 13-first heat-sealing layer; 14-functional coating layer; 15-second heat-sealing layer. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. If specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are adopted. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0053] The sealing film provided by the present application and the preparation method and application thereof and the package will be described in detail below.

[0054] The present application provides a sealing film 10, which is not in the absolute sense of a film form, and can be in the form of a coating layer or a film.

[0055] Please refer to Figure 1 The sealing film 10 includes a film body 12 and a functional coating layer 14, and the functional coating layer 14 is arranged on the surface of the film body 12.

[0056] The film body 12 can be used as a support layer to provide strength and barrier effect for the sealing film 10. In some embodiments, the film body 12 can include an aluminum foil or a plastic film, etc. The aluminum foil has high strength and complete barrier properties.

[0057] In some embodiments, the thickness of the film body 12 is 20 μm to 200 μm, such as 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm or 200 μm, etc.

[0058] As an example, when an aluminum foil is used as the film body 12, its thickness can be exemplarily 60 μm to 90 μm; when a plastic film or the like is used as the film body 12, its thickness can be exemplarily greater than or equal to 150 μm. In some embodiments, the functional coating layer 14 can be directly arranged on the surface of the film body 12, or indirectly arranged on the surface of the film body 12. The "indirectly arranged" can be understood as that there is another structure between the film body 12 and the functional coating layer 14.

[0059] In the technical solution of the present application, the functional coating layer 14 contains a noble metal capable of catalyzing the hydrogen-oxygen reaction; the functional coating layer 14 has at least a region satisfying E=c×h, E≥150, h≥2, c≥50; wherein the thickness value of the region is h in μm; and the concentration value of the noble metal in the region is c in ppm.

[0060] In some embodiments, the noble metal in the functional coating 14 is in a uniform distribution, and correspondingly, the thickness of the functional coating 14 is h (in μm), and the concentration of the noble metal in the functional coating 14 is c (in ppm), and c and h satisfy the following equation: E = c x h, E ≥ 150, h ≥ 2, and c ≥ 50.

[0061] In other embodiments, the noble metal in the functional coating 14 is in a non-uniform distribution, for example, the noble metal is not uniformly distributed in the thickness direction and / or in the horizontal plane, in which case, as long as there is a region in the functional coating 14 that satisfies the equation: E = c x h, E ≥ 150, h ≥ 2, and c ≥ 50 (the thickness of the region is h (in μm), and the concentration of the noble metal in the region is c (in ppm)), the functional coating 10 can be used. It should be noted that the number of regions in the functional coating 14 that satisfy the above conditions can be only one, or two or more.

[0062] The above-mentioned film 10 is used to absorb oxygen by consuming the oxygen in the package containing the film 10 in the presence of hydrogen. Specifically, the film 10 consumes the oxygen in the package by catalyzing the hydrogen-oxygen reaction between hydrogen and oxygen in the presence of both hydrogen and oxygen in the package.

[0063] The above-mentioned functional coating 14 contains noble metal that can catalyze the hydrogen-oxygen reaction, and can catalyze the reaction between hydrogen and oxygen, which is conducive to reducing the oxygen content. By limiting the relationship between h and c, the functional coating 14 can solidify the water generated during the hydrogen-oxygen reaction, and on this basis, can ensure that the generated water can open the gas migration channel in the functional coating 14, accelerate the diffusion of hydrogen and oxygen in the container into the functional coating 14, further accelerate the consumption and removal of oxygen, and the functional coating 14 that satisfies the above equation can achieve the basic removal of oxygen and water. In addition, by embodying the noble metal that can catalyze the hydrogen-oxygen reaction in the form of a coating, the risk of migration and shedding of the noble metal during the shelf life can be reduced or avoided.

[0064] As an example, the above-mentioned noble metal can include at least one of Pd and Pt, but is not limited thereto. Preferably, Pd is included for cost considerations.

[0065] In some embodiments, the noble metal is in a particulate form; in other embodiments, the noble metal is in a non-particulate form.

[0066] In some embodiments, the size of the noble metal is in the nanometer to micrometer range. In some typical embodiments, the noble metal is in a particulate form, and the particle size is 10 nm to 20 nm, such as 10 nm, 12 nm, 15 nm, 18 nm, or 20 nm, etc.

[0067] In some embodiments, the noble metal in the functional coating 14 is in a concentration level of ppm, which can save cost while playing a role and reducing or avoiding possible food safety risks. Exemplarily, the concentration of the noble metal in the functional coating 14 can be 200 ppm to 500 ppm, such as 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm or 500 ppm, etc.

[0068] In some embodiments, the thickness of the functional coating 14 is 2 μm to 10 μm, such as 2 μm, 4 μm, 6 μm, 8 μm or 10 μm, etc. In some preferred embodiments, the thickness of the functional coating 14 is 5 μm to 7 μm, such as 5 μm, 5.5 μm, 6 μm, 6.5 μm or 7 μm, etc.

[0069] The number of layers of the functional coating 14 described above can be one layer or multiple layers, and the total thickness of each layer of the functional coating 14 is ≥ 2 μm. When the number of layers of the functional coating 14 is multiple layers, it can be a multiple layer palladium coating, a multiple layer platinum coating, or a multiple layer palladium coating and a multiple layer platinum coating arranged alternately. In addition, in the same layer of the functional coating 14, it can contain only palladium, only platinum, or both palladium and platinum.

[0070] In some embodiments, in addition to the oxygen absorption function, the functional coating 14 described above can also provide a certain heat sealing effect, and in this case, the functional coating 14 also contains a component having a heat sealing effect.

[0071] The above-mentioned sealing film 10 also includes a first heat sealing layer 13, which is arranged on the surface of the film body 12, and the functional coating 14 is arranged on the side surface of the first heat sealing layer 13 away from the film body 12.

[0072] The first heat sealing layer 13 is mainly used to provide a heat sealing effect. The thickness of the first heat sealing layer 13 can be ≤ 15 μm, such as 15 μm, 12 μm, 10 μm, 8 μm, 5 μm or 2 μm, etc.

[0073] In some optional embodiments, as shown in Figure 2 The above-mentioned sealing film 10 can also include a second heat sealing layer 15, which is arranged on the side surface of the functional coating 14 away from the first heat sealing layer 13. That is, the second heat sealing layer 15 is an optional arrangement layer, which is arranged or not arranged according to actual needs.

[0074] The second heat sealing layer 15 can provide a heat sealing function while also isolating the packaging content from the functional coating 14, which can be suitable for the case where the content in the package has strong permeability.

[0075] The thickness of the second heat-seal layer 15 can be ≤ 15 μm, such as 15 μm, 12 μm, 10 μm, 8 μm, 5 μm or 2 μm, etc.

[0076] The heat-seal materials of the first heat-seal layer 13 and the second heat-seal layer 15 can be set according to the prior art, and any material capable of achieving heat-sealing can be used. It should be noted that when the package is a food package, the heat-seal material also needs to meet the requirements in the food field.

[0077] Further, the sealing film 10 can further comprise an additional layer 11 disposed on the surface of the film body 12 on the side opposite to the first heat-seal layer 13.

[0078] By way of illustration, the additional layer 11 can exemplarily but non-limitatively comprise a varnish coating capable of protecting the surface of the film body 12. In addition, it is also not excluded that other additional layers 11 having other functions can be provided as needed.

[0079] The thickness of the additional layer 11 can be 2 μm to 8 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm or 8 μm, etc.

[0080] In some specific embodiments, the sealing film 10 can comprise, in the direction from top to bottom, the additional layer 11, the film body 12, the first heat-seal layer 13, the functional coating 14 and the second heat-seal layer 15. In other embodiments, in addition to the additional layer 11 and the second heat-seal layer 15 which can be selectively provided and replaced, it is also not excluded that other coating layers can be additionally added between the layers.

[0081] In some embodiments, the total thickness of the first heat-seal layer 13, the functional coating 14 and the second heat-seal layer 15 is not more than 20 μm, such as 20 μm, 18 μm, 15 μm, 12 μm, 10 μm, 8 μm or 5 μm, etc.

[0082] The sealing film 10 described above not only has the advantages of oxygen removal and water absorption, but also has good adhesion strength between the sealing film 10 and the package body. In addition, the sealing film 10 described above can be a disposable film which is not used after being torn, thereby avoiding excessive contact between the content and the sealing film 10.

[0083] In addition, the present application also provides a preparation method of the sealing film 10 described above, comprising the following steps: disposing each structural layer on the surface of the film body 12 at a predetermined position.

[0084] For example, the preparation slurry of each structural layer is coated at the predetermined position, dried, and then heat-sealed as needed.

[0085] The slurry for preparing the functional coating 14 includes a noble metal dispersion liquid and an adhesive. The adhesive can exemplarily but not limitatively be an adhesive of an acrylic system and / or a polyester system. Different adhesive systems can further include a water-based adhesive or an oil-based adhesive. In some exemplary embodiments, the adhesive used for preparing the slurry can be, for example, Michelman Prime 498345N, Henkel LOCTITE LIOFOL HS1147, and / or Guangzhou Hongtai 13084, etc. The adhesive can be selected and used according to actual needs.

[0086] The solid content of the slurry for preparing the functional coating 14 can be 30% to 45%, such as 30%, 32%, 34%, 36%, 40%, 42%, or 45%, etc., or other values within the range of 30% to 45%.

[0087] The mass ratio of the noble metal dispersion liquid to the adhesive can be 80:20 to 90:10, such as 80:20, 81:19, 82:18, 83:17, 84:16, 85:15, 86:14, 87:13, 88:12, 89:11, or 90:10, etc., or other arbitrary values within the range of 80:20 to 90:10.

[0088] The concentration of the noble metal in the noble metal dispersion liquid can be 500 ppm to 10000 ppm, such as 500 ppm, 1000 ppm, 2000 ppm, 4000 ppm, 6000 ppm, 8000 ppm, or 10000 ppm, etc., or other values within the range of 500 ppm to 10000 ppm.

[0089] The noble metal dispersion liquid can be an organic solvent type noble metal dispersion liquid or a water type noble metal dispersion liquid. The carrier in the organic solvent type noble metal dispersion liquid is mainly an organic reagent (such as ethyl acetate), and the carrier in the water type noble metal dispersion liquid is mainly water.

[0090] In some embodiments, the water type noble metal dispersion liquid is obtained by mixing water and noble metal. The concentration of the noble metal in the water type noble metal dispersion liquid is 500 ppm to 10000 ppm. The adhesive corresponding to the water type noble metal dispersion liquid can exemplarily but not limitatively be Michelman Prime 498345N, etc.

[0091] In some embodiments, the organic solvent type noble metal dispersion liquid is obtained by mixing ethyl acetate and noble metal. The concentration of noble metal in the organic solvent type noble metal dispersion liquid is 500 ppm to 10000 ppm. The adhesive used in the organic solvent type noble metal dispersion liquid can exemplarily but not limitatively be Han Gao LOCTITE LIOFOL HS1147 and / or Guangzhou Hongtai 13084, etc.

[0092] In some embodiments, the coating amount of the functional coating 14 can be 2 g / m 2 ~ 10 g / m 2 , such as 2 g / m 2 , 3 g / m 2 , 4 g / m 2 , 5 g / m 2 , 6 g / m 2 , 7 g / m 2 , 8 g / m 2 , 9 g / m 2 or 10 g / m 2 , etc., or any other value within the range of 2 g / m 2 ~ 10 g / m 2 . The number of coating times of the functional coating 14 in the coating process can be only 1, or 2 or more, and the total coating amount is controlled within the above range. In some embodiments, the coating amount can be 1 g / m 2 corresponding to 1 μm; in other embodiments, the relationship between the coating amount and the thickness can be adjusted according to the actual situation.

[0093] In some embodiments, the coating speed of the functional coating 14 can be 30 m / min to 100 m / min, such as 30 m / min, 40 m / min, 50 m / min, 60 m / min, 70 m / min, 80 m / min, 90 m / min or 100 m / min, etc., or any other value within the range of 30 m / min to 100 m / min.

[0094] The above coating can be performed by using a screen roller, and other coating equipment is not excluded.

[0095] In some embodiments, the drying temperature of the functional coating 14 can be 80°C to 130°C, such as 80°C, 90°C, 100°C, 110°C, 120°C or 130°C, etc., or any other value within the range of 80°C to 130°C.

[0096] In some other embodiments, the functional coating 14 can also be prepared without using adhesive, for example, by dispersing noble metal in PP or PE, and using a lamination film instead of coating to prepare the functional coating 14 to be attached to the surface of the film body 12.

[0097] The hydrogen-oxygen reaction mentioned in the present application is carried out on the interface of the catalyst, and the water generated by the curing of the coating system of the coating can avoid the generated water molecules from escaping into the powder to cause agglomeration, and on the other hand, the water as a plasticizer can open the gas migration channel in the coating to further accelerate the removal of oxygen. If the noble metal is not in the form of a coating but is used alone, it not only causes the risk of foreign matter, but also the water generated by the reaction of oxygen and hydrogen cannot be discharged, which is easy to cause the content sensitive to water to be caked.

[0098] It should be noted that the preparation process and conditions of other structural layers involved in the present application can refer to the related prior art, and will not be described and limited too much here. In addition, the present application also provides an application of the above-mentioned sealing film 10, which is used to consume the oxygen in the package containing the sealing film 10, and further can play the role of oxygen absorption and water absorption.

[0099] Correspondingly, the present application also provides a package, which comprises a package body.

[0100] In some embodiments, the sealing end of the package body has the above-mentioned sealing film 10.

[0101] In some other embodiments, the package body is composed of the above-mentioned sealing film 10.

[0102] The above-mentioned package body has residual oxygen and an oxygen-free and water-free mixed gas containing hydrogen and inert gas (exemplary but non-limiting inert gas can include nitrogen and the like). Specifically, after sealing, the package can ensure that the inside has the above-mentioned mixed gas. Among them, hydrogen as a reaction gas is used to consume the residual oxygen in the package. The oxygen that may exist in the package body is reacted with hydrogen in the package body under the catalysis of the noble metal of the functional coating 14 to realize the hydrogen-oxygen reaction of hydrogen and oxygen, thereby playing the effect of removing oxygen in the package body.

[0103] In some embodiments, after packaging, the hydrogen content in the package is at least 2 times the residual oxygen content in the package, so that the residual oxygen is completely reacted.

[0104] In some embodiments, after packaging, the residual oxygen content in the package is not more than 3% (such as 2% to 3%). Correspondingly, after packaging, the hydrogen content in the package can be below 10%, but needs to meet the minimum value of the theoretical residual oxygen reaction. As an example, after packaging, the hydrogen content in the package can be 2% to 10%.

[0105] In some embodiments, the material of the above-mentioned package body includes a metal-containing material, for example, a material containing iron and / or aluminum, and in addition, other materials such as PET material can also be set according to product needs. In some special ways, the package body can also be a metal-containing paper-based packaging material.

[0106] In some embodiments, the packaging body further comprises an oxygen-sensitive content. The content exemplarily but non-limitatively can comprise dairy products, such as milk powder and / or protein powder, etc.

[0107] In some typical embodiments, the packaging is a milk powder can and / or a protein powder can.

[0108] It should be noted that conventional milk powder filling is limited by the process and cannot completely remove oxygen in the can, but can only maintain about 2% to 3%, which is not conducive to oxygen-sensitive formula ingredients. Some milk powder oxygen removal methods use oxygen removal bags (such as iron powder), but there is a risk of foreign matter.

[0109] By providing the sealing film 10 containing the functional coating 14 at the sealing end of the milk powder can, on the one hand, under the catalytic action of the noble metal in the functional coating 14, in cooperation with the hydrogen in the milk powder can, the hydrogen and oxygen can react to generate water, thereby consuming the oxygen in the can body, and achieving an oxygen-free state (such as being able to reach an oxygen-free state within 15 days after sealing) during transportation or shelf life. On the other hand, the functional coating 14 can absorb the generated water to prevent the milk powder from caking. In addition, the functional coating 14 can also form an oxygen channel to accelerate oxygen consumption.

[0110] It should be noted that the "oxygen-free state" means that the oxygen content in the milk powder can is not higher than 1% (volume percentage), preferably not higher than 0.5%, more preferably not higher than 0.1%, and further preferably 0%.

[0111] The features and performances of the present application are further described in detail below in combination with examples.

[0112] Example 1

[0113] This example provides a sealing film 10, as shown, in the direction from top to bottom, the sealing film 10 comprises an additional layer 11, a film body 12, a first heat sealing layer 13 and a functional coating 14 which are sequentially stacked. Figure 1

[0114] Among them, the additional layer 11 is a varnish coating, and the film body 12 is an aluminum foil. The total thickness of the above sealing film 10 is 105.5 μm, the thickness of the additional layer 11 is 5 μm, the thickness of the film body 12 is 90 μm, and the thickness of the first heat sealing layer 13 is 8 μm.

[0115] The functional coating 14 contains uniformly distributed Pd particles, the concentration of Pd particles in the functional coating 14 is 360 ppm, and the particle size of the Pd particles is 10 nm to 20 nm; the thickness of the functional coating 14 is 2.5 μm. Correspondingly, E = c x h = 360 x 2.5 = 900.

[0116] ​Example 2

[0117] This embodiment provides a sealing film 10, which differs from Embodiment 1 in that: the concentration of Pd particles in the functional coating 14 is 200 ppm, and the particle size of the Pd particles is 10 nm to 20 nm; the thickness of the functional coating 14 is 5 μm. Accordingly, E = c × h = 200 × 5 = 1000.

[0118] Example 3

[0119] This embodiment provides a sealing film 10, which differs from Embodiment 1 in that: the concentration of Pd particles in the functional coating 14 is 500 ppm, and the particle size of the Pd particles is 10 nm to 20 nm; the thickness of the functional coating 14 is 7 μm. Accordingly, E = c × h = 500 × 7 = 3500.

[0120] Example 4

[0121] This embodiment provides a sealing film 10, which differs from Embodiment 1 in that: the concentration of Pd particles in the functional coating 14 is 600 ppm, and the particle size of the Pd particles is 10 nm to 20 nm; the thickness of the functional coating 14 is 10 μm. Accordingly, E = c × h = 600 × 10 = 6000.

[0122] Example 5

[0123] This embodiment provides a sealing film 10, which differs from Embodiment 1 in that: the concentration of Pd particles in the functional coating 14 is 50 ppm, and the particle size of the Pd particles is 10 nm to 20 nm; the thickness of the functional coating 14 is 3 μm. Accordingly, E = c × h = 50 × 3 = 150.

[0124] Example 6

[0125] This embodiment provides a sealing film 10, which differs from Embodiment 1 in that: the concentration of Pd particles in the functional coating 14 is 75 ppm, and the particle size of the Pd particles is 10 nm to 20 nm; the thickness of the functional coating 14 is 2 μm. Accordingly, E = c × h = 75 × 2 = 150.

[0126] Example 7

[0127] like Figure 2 As shown, the difference between this embodiment and embodiment 1 is that the lower surface of the functional coating 14 is further provided with a second heat-sealing layer 15, and the thickness of the second heat-sealing layer 15 is 4μm.

[0128] Example 8

[0129] The difference between this embodiment and Embodiment 1 is that it does not include the additional layer 11.

[0130] Example 9

[0131] The embodiment provides a preparation method of the functional coating 14, and the preparation method comprises the following steps:

[0132] S1: Pd particles and water are mixed to obtain a water type noble metal dispersion liquid with a Pd particle concentration of 2000 ppm;

[0133] S2: The water type noble metal dispersion liquid is mixed with an adhesive (Michelman Prime 498345N) at a mass ratio of 82:18 to obtain a preparation slurry with a solid content of 45%;

[0134] S3: The preparation slurry is coated on a substrate surface (aluminum foil), the coating times are 2, the total coating amount is 7 g / m 2 , and the coating speed is 50 m / min;

[0135] S4: After coating, drying is performed at 100 ℃.

[0136] Embodiment 10

[0137] The embodiment provides a preparation method of the functional coating 14, and the preparation method comprises the following steps:

[0138] S1: Pd particles and water are mixed to obtain a water type noble metal dispersion liquid with a Pd particle concentration of 2000 ppm;

[0139] S2: The water type noble metal dispersion liquid is mixed with an adhesive (Guangzhou Hongtai 13084) at a mass ratio of 80:20 to obtain a preparation slurry with a solid content of about 30%;

[0140] S3: The preparation slurry is coated on a substrate surface (aluminum foil), the coating times are 2, the total coating amount is 10 g / m 2 , and the coating speed is 50 m / min;

[0141] S4: After coating, drying is performed at 80 ℃.

[0142] Embodiment 11

[0143] The embodiment provides a preparation method of the functional coating 14, and the preparation method comprises the following steps:

[0144] S1: Pd particles and water are mixed to obtain a water type noble metal dispersion liquid with a Pd particle concentration of 2000 ppm;

[0145] S2: The water type noble metal dispersion liquid is mixed with an adhesive (Han Gao LOCTITE LIOFOL HS 1147) at a mass ratio of 90:10 to obtain a preparation slurry with a solid content of about 40%;

[0146] S3: The prepared slurry was coated on the surface of the substrate (aluminum foil), the coating was repeated twice, and the total coating amount was 5 g / m 2 , and the coating speed was 100 m / min.

[0147] S4: After coating, drying was performed at 130°C.

[0148] Example 12

[0149] This example provides a milk powder can, which comprises a can body made of iron, and the sealing end of the can body is provided with the sealing film 10 provided in Example 1, and the functional coating in the sealing film can be prepared according to the method in Example 9. The headspace of the can body is filled with nitrogen containing hydrogen. The content of hydrogen is 2 times the residual oxygen content in the can body.

[0150] Test Example 1

[0151] Taking Example 12 as an example, the functional coating 14 was adjusted to form different experimental groups, and the adjustment included adjusting the concentration of Pd in the prepared slurry and the coating amount in terms of wet weight, wherein different coating amounts corresponded to different thicknesses of the functional coating. For a specific experimental group, when the functional coating reached the critical gram weight for effectiveness, the functional coating met the minimum thickness for effectiveness. After testing, the relationship between the oxygen content in the milk powder can and the number of days of placement in each experimental group was tested, and the results are shown in Figure 3 .

[0152] Referring to Figure 3 , it is specifically divided into 9 experimental groups, which are sequentially recorded as "20-5", "20-7", "20-10", "15-5", "15-7", "15-10", "10-5", "10-5" and "10-10". Taking "20-5" as an example, wherein "20" refers to the mass percentage of Pd dispersion liquid in the prepared slurry, and the unit is %; "5" refers to the coating amount in terms of wet weight, and the unit is g / m 2 . Figure 3 The abscissa is the number of days, and the unit is days; the ordinate is the oxygen content, and the unit is %.

[0153] As can be seen from Figure 3 , the effects of some experimental groups are not ideal, and the effects of the remaining experimental groups can play a role in removing residual oxygen.

[0154] ①, referring to Figure 4 , Figure 4 , the test results of the 3 experimental groups "20-5", "15-5" and "10-5" in Figure 3 , among the 3 experimental groups, the solid content of the prepared slurry is 36%, and the coating amount in terms of wet weight is 5 g / m 2, the concentration of Pd particles in the dispersion liquid was 2000 ppm, the mass ratio of the adhesive to the dispersion liquid in the "20-5" group was 80:20 (i.e. the mass percentage of the Pd dispersion liquid in the preparation slurry was 20%, and the concentration of Pd in the preparation slurry was 400 ppm accordingly); the mass ratio of the adhesive to the dispersion liquid in the "15-5" group was 85:15 (i.e. the mass percentage of the Pd dispersion liquid in the preparation slurry was 15%, and the concentration of Pd in the preparation slurry was 300 ppm accordingly); the mass ratio of the adhesive to the dispersion liquid in the "10-5" group was 90:10 (i.e. the mass percentage of the Pd dispersion liquid in the preparation slurry was 10%, and the concentration of Pd in the preparation slurry was 200 ppm accordingly).

[0155] By Figure 4 It can be seen that: under the condition that the coating amount in terms of wet weight was 5 g / m 2 , no matter whether the concentration of Pd in the preparation slurry was 400 ppm, 300 ppm or 200 ppm, the content of palladium in the corresponding functional coating was greater than 50 ppm, but since the critical coating weight for the onset of effect had not been reached, i.e. the thickness of the functional coating was relatively thin, the value of E was < 150, and the oxygen concentration in the milk powder tank remained basically constant without reduction as the days increased, and the residual oxygen content was still above 1.5%, which did not have the effect of removing residual oxygen.

[0156] ②, refer to Figure 5 , Figure 5 for Figure 3 the test results of the "15-10" experimental group in Table 1, in the experimental group, the solid content of the preparation slurry was 36%, the coating amount in terms of wet weight was 10 g / m 2 , the concentration of Pd particles in the dispersion liquid was 2000 ppm, and the mass ratio of the adhesive to the dispersion liquid was 85:15 (i.e. the mass percentage of the Pd dispersion liquid in the preparation slurry was 15%, and the concentration of Pd in the preparation slurry was 300 ppm accordingly), which met the condition of E > 150.

[0157] The result curve of the experimental group is a typical curve for the onset of effect, showing a reverse S characteristic, indicating that in the experimental group, the onset process is divided into three stages.

[0158] Stage I: mainly controlled by the adsorption and diffusion of gas, this stage is controlled by the diffusion speed of gas in the dense coating, and the speed decreases slowly (smaller slope);

[0159] Stage II: in this stage, part of the hydrogen-oxygen reaction generates water, which is locked in the coating and cannot escape into the space in the container, thereby avoiding the problem of possible clumping of the milk powder due to the absorption of moisture; on the other hand, it can play the role of a plasticizer, destroying the density of the coating and facilitating the subsequent diffusion process of hydrogen and oxygen gas, so the slope of the curve in this stage shows an accelerating pattern;

[0160] Stage III: At this time, the hydrogen and oxygen concentrations in the tank are significantly reduced, resulting in a decrease in the adsorption and even diffusion concentration on the surface of the coating. In this process, the reaction rate is affected by the concentration, and the slope becomes slower.

[0161] ③、Refer to Figure 6 , Figure 6 As Figure 3 the test results of the "20-7", "15-7" and "10-7" experimental groups in Example 1.

[0162] From Figure 6 It can be seen that the above three experimental groups have played a role in removing residual oxygen. Under the premise of taking effect, with the same coating thickness and different Pd concentrations, the higher the Pd concentration, the faster the oxygen concentration decreases.

[0163] ④、Refer to Figure 7 , Figure 7 As Figure 3 the test results of the "15-5", "15-7" and "15-10" experimental groups in Example 2.

[0164] From Figure 7 It can be seen that the above three experimental groups have played a role in removing residual oxygen. Under the premise of taking effect, with the same coating thickness and different Pd concentrations, the higher the Pd concentration, the faster the oxygen concentration decreases.

[0165] Test Example 2

[0166] The TBA value (thiobarbituric acid value) is used to characterize the oxidation problem of the product (milk powder) affected by headspace oxygen. Unsaturated fatty acid oxidation products aldehydes can form colored compounds with thiobarbituric acid (TBA).

[0167] Example 12 is taken as a test sample, and a comparative sample is set. The comparative sample is to place Pd in the form of a palladium ball in the milk powder tank, and the diameter of the palladium ball is 2 mm, and the palladium loading amount is 1000 ppm.

[0168] The headspace oxygen concentration of the comparative sample is 2.6%, and after 3 months, the TBA value of the comparative sample is 0.12; under the same conditions, the TBA value of the test sample of the present application Example 12 is 0.033, which is significantly lower than that of the comparative sample.

[0169] In summary, the functional coating 14 of the sealing film 10 contains noble metals capable of catalyzing the hydrogen-oxygen reaction, which can catalyze the hydrogen-oxygen reaction and is conducive to reducing the oxygen content; the functional coating 14 can also solidify the generated water, and the generated water can open the gas migration channel in the functional coating 14, further accelerating the removal of oxygen; by coating the noble metals capable of catalyzing the hydrogen-oxygen reaction, the risk of migration and shedding of the noble metals during the shelf process can be reduced or avoided. The sealing film 10 described above has oxygen removal and water absorption effects, and can be further used for various types of packaging, such as food packaging of milk powder and the like.

[0170] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art based on the principles and spirit of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A sealing film, characterized in that, The sealing film includes a membrane body and a functional coating disposed on the surface of the membrane body; the functional coating contains a noble metal capable of catalyzing the hydrogen-oxygen reaction; the functional coating has at least a region satisfying E = c × h, E ≥ 150, h ≥ 2, c ≥ 50; wherein, in μm, the thickness of the region is h; and in ppm, the concentration of the noble metal in the region is c.

2. The sealing film according to claim 1, characterized in that, The sealing film is used to absorb oxygen by consuming the oxygen inside the packaging containing the sealing film in the presence of hydrogen.

3. A sealing film with oxygen absorption effect, characterized in that, The sealing film includes a membrane body and a functional coating disposed on the surface of the membrane body; the functional coating contains a noble metal capable of catalyzing the hydrogen-oxygen reaction; the functional coating has at least a region satisfying E = c × h, E ≥ 150, h ≥ 2, c ≥ 50; wherein, in μm, the thickness of the region is h; and in ppm, the concentration of the noble metal in the region is c. The sealing film is used to consume oxygen within the packaging containing the sealing film in the presence of hydrogen.

4. The sealing film according to claim 2 or 3, characterized in that, When the sealing film contains both hydrogen and oxygen within the packaging, the hydrogen and oxygen undergo a hydrogen-oxygen reaction through the catalytic action of the precious metal, thereby consuming the oxygen within the packaging.

5. The sealing film according to any one of claims 1 to 3, characterized in that, The thickness of the functional coating is h in μm; the concentration of the noble metal in the functional coating is c in ppm, where c and h satisfy: E = c × h, E ≥ 150, h ≥ 2, c ≥ 50. Preferably, the thickness of the functional coating is 2μm to 10μm; Preferably, the thickness of the functional coating is 5 μm to 7 μm.

6. The sealing film according to any one of claims 1 to 3, characterized in that, The precious metal has at least one of the following characteristics: Feature 1: The precious metal includes at least one of Pd and Pt; Feature 2: The particle size of the precious metal is 10nm to 20nm; Feature 3: The concentration of the precious metal in the functional coating is at the ppm level.

7. The sealing film according to any one of claims 1 to 3, characterized in that, The sealing film further includes a first heat-sealing layer, which is disposed on the surface of the film body, and the functional coating is disposed on the side of the first heat-sealing layer away from the film body; Preferably, the sealing film further includes a second heat-sealing layer, which is disposed on the side surface of the functional coating away from the first heat-sealing layer; Preferably, the sealing film further includes an additional layer disposed on the surface of the film body on the side opposite to the first heat-sealing layer; Preferably, the additional layer includes a clear coat; Preferably, the membrane body comprises aluminum foil or plastic film; Preferably, the total thickness of the first heat-sealing layer, the functional coating, and the second heat-sealing layer does not exceed 20 μm.

8. A method for preparing a sealing film as described in any one of claims 1 to 7, characterized in that, The steps include: setting a structural layer on the surface of the membrane body at a preset position; Preferably, the preparation slurry for each structural layer is applied to a predetermined position and dried; Preferably, the slurry for preparing the functional coating includes a noble metal dispersion and an adhesive; Preferably, the mass ratio of the precious metal dispersion to the adhesive is 80:20 to 90:10; Preferably, the concentration of the precious metal in the precious metal dispersion is 500 ppm to 10000 ppm; Preferably, the precious metal dispersion is an organic solvent-based precious metal dispersion or an aqueous precious metal dispersion, wherein the carrier in the organic solvent-based precious metal dispersion is mainly an organic reagent, and the carrier in the aqueous precious metal dispersion is mainly water; Preferably, the coating amount of the functional coating is 2 g / m². 2 ~10g / m 2 And / or, the coating speed of the functional coating is 30m / min to 100m / min; Preferably, the drying temperature of the functional coating is 80℃~130℃.

9. An application of the sealing film as described in any one of claims 1 to 7, characterized in that, The sealing film is used to consume the oxygen inside the packaging containing the sealing film.

10. A type of packaging, characterized in that, The packaging includes a packaging body, the sealing end of which has a sealing film as described in any one of claims 1 to 7, or the packaging body is composed of a sealing film as described in any one of claims 1 to 7; Preferably, the packaging body contains residual oxygen and a mixture of hydrogen and inert gas; preferably, after sealing, the hydrogen content in the packaging is at least twice the amount of residual oxygen in the packaging. Preferably, the material of the packaging body includes a metal-containing material; Preferably, the metal-containing material includes materials containing iron and / or aluminum; Preferably, the packaging body also includes oxygen-sensitive contents; Preferably, the contents include dairy products; Preferably, the contents include milk powder and / or protein powder.

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