CN113912894B - A kind of transparent high-barrier polyester aluminum oxide coating film and preparation method thereof - Google Patents

Abstract

The application relates to the field of aluminized films, and specifically discloses a transparent high-barrier polyester aluminum oxide-plated film and a preparation method thereof. A transparent high-barrier polyester aluminum oxide-coated film, comprising a substrate, a polyurethane primer layer, an aluminum oxide layer and a polyurethane topcoat layer arranged in sequence, wherein the thickness of the polyurethane primer layer and the thickness of the polyurethane topcoat layer are both 8-15 μm, the thickness of the aluminum oxide layer is 80-140 angstroms, the polyurethane base coating is formed by drying the polyurethane coating liquid, and the polyurethane top coating is formed by drying the polyurethane coating liquid. The preparation method is as follows: S1. obtaining a primer film on a polyurethane primer layer of a base material; S2. forming an aluminum oxide layer on the polyurethane primer layer to obtain an initial plating film; S3. forming a polyurethane topcoat layer on the aluminum oxide layer , aging to obtain a transparent high-barrier polyester coated aluminum oxide film. The aluminum oxide-coated film of the present application has the advantages of good retort resistance and barrier properties.

Description

A kind of transparent high-barrier polyester aluminum oxide coating film and preparation method thereof

technical field

The present application relates to the field of aluminized films, and more particularly, to a transparent high-barrier polyester aluminum oxide-coated film and a preparation method thereof.

Background technique

With the improvement of people's living standards, people pay more and more attention to quality issues when shopping, especially in the field of food, so the food for sale is generally covered with outer packaging. The outer packaging of food is mainly to slow down the speed of food spoilage. The outer packaging is generally composed of multi-layer films. The film is roughly divided into a heat-sealing layer, a barrier layer and a printing layer. The function of the barrier layer is to block water and oxygen from the outside world. , to delay the spoilage effect of water and oxygen on food.

At present, there are many kinds of barrier layers on the market, including aluminized film and nylon film. Since aluminized film is opaque, it is inconvenient for customers to observe the state of food if it is used for packaging food; nylon film is transparent and has high strength. It has good barrier properties, but it is easily affected by ultraviolet rays and has limited application scenarios. Therefore, new materials are also required as the barrier layer.

Alumina-coated film is a kind of transparent film, which is a kind of film in which high-purity aluminum wire is evaporated into gaseous state at high temperature, oxygen is introduced to obtain aluminum oxide, and aluminum oxide is deposited on the film substrate. Oxygen barrier properties and water vapor barrier properties are good, so it has excellent barrier properties, but at higher temperatures, such as above 110 °C, the structural stability of the aluminum oxide film is poor, and problems such as deformation and interlayer peeling are prone to occur, namely The cooking resistance needs to be improved.

SUMMARY OF THE INVENTION

In order to obtain an alumina-coated film with good retort resistance, the present application provides a transparent high-barrier polyester alumina-coated film and a preparation method thereof.

In the first aspect, the present application provides a transparent high-barrier polyester aluminum oxide-coated film, which adopts the following technical solution: a transparent high-barrier polyester aluminum oxide-coated film, which includes a substrate, a polyurethane primer coating, an oxidized an aluminum layer and a polyurethane top coat, the thickness of the polyurethane base coat and the thickness of the polyurethane top coat are both 8-15 μm, the thickness of the alumina layer is 80-140 angstroms, the polyurethane base coat and the polyurethane top coat The top coats are all dried from a polyurethane coating solution.

By adopting the above technical solutions, the polyurethane primer coat improves the surface smoothness of the substrate, helps the deposition of aluminum oxide, and forms an aluminum oxide layer that is stably connected to the substrate; the polyurethane top coat covers and protects the aluminum oxide layer, effectively preventing external Improve the strength of the film when the alumina layer is scratched or damaged.

In addition, through the sequence setting of the polyurethane primer layer, the aluminum oxide layer and the polyurethane topcoat layer, and the coordination of the thickness of the polyurethane topcoat layer, the aluminum oxide layer and the polyurethane primer layer within a specific range, the polyurethane topcoat layer can be made of aluminum oxide. The lamination is stabilized on the polyurethane primer layer, which improves the stability of the aluminum oxide layer, so that the aluminum oxide layer can maintain a stable state in the film even at high temperature, and the polyurethane primer layer and the polyurethane topcoat layer make the two sides of the aluminum oxide layer stable. When squeezed, alumina improves the compactness of the alumina layer, which not only improves the barrier property, but also improves the structural stability of the film at high temperature, making the film more suitable for the packaging of foods requiring high temperature heating.

Optionally, the polyurethane coating liquid includes the following raw materials by weight: 90-100 parts of an aqueous polyurethane dispersion, 45-60 parts of a diluent, and 2-8 parts of a cross-linking agent.

By adopting the above technical solutions, the polyurethane is flexible and wear-resistant, the water-based polyurethane has high adhesion, and is more environmentally friendly than the solvent-based polyurethane, with less residual harmful solvents, and is more suitable for food packaging. Helps to disperse water-based polyurethane evenly, thereby improving the uniformity of polyurethane basecoat and polyurethane topcoat.

Optionally, the diluent is a composition composed of isopropanol and water, wherein the weight ratio of isopropanol and water is 1:(4-6), preferably, the weight ratio of isopropanol and water is 1:5.

Optionally, the cross-linking agent is an aziridine cross-linking agent.

Optionally, the raw material of the polyurethane coating liquid also includes 20-25 parts by weight of modified silica sol, and the modified silica sol is composed of silica sol, 2,2′-diphenylene The raw materials of methane diisocyanate, Span 80, catalyst and solvent are made, and the weight ratio of described silica sol, 2,2'-diphenylmethane diisocyanate, Span 80, catalyst and solvent is 10:(0.12～ 0.22): (1 to 1.5): (0.0008 to 0.002): (10 to 20).

By adopting the above technical solution, the doping of silica sol in the polyurethane coating solution helps to improve the mechanical properties of the polyurethane coating. The isocyanate groups are staggered and have good compatibility with water-based polyurethane, which not only improves the uniformity of the silica component in the water-based polyurethane, but also improves the tightness of the water-based polyurethane and improves the density of the polyurethane coating. properties to further improve retort resistance and barrier properties.

Optionally, the solvent is isopropanol, and the catalyst is dibutyltin diacetate.

Optionally, the substrate is selected from one of CPP, BOPP, PET, PA, PLA and PE.

In the second aspect, the present application provides a method for preparing a transparent high-barrier polyester aluminum oxide-coated film, which adopts the following technical solutions:

A preparation method of a transparent high-barrier polyester aluminum oxide-coated film, comprising the following steps:

S1. Coating a polyurethane coating solution on the substrate, drying, and forming a polyurethane primer layer on the substrate to obtain a primer film;

S2. The primer film is sent to the vacuum aluminizing equipment, vacuumed, the aluminum wire is heated, and oxygen is introduced to form an aluminum oxide layer on the polyurethane primer layer to obtain the initial plating film;

S3. Coating a polyurethane coating solution on the alumina layer, drying, forming a polyurethane surface coating on the alumina layer, and curing to obtain a transparent high-barrier polyester alumina-coated film.

By adopting the above technical scheme, a polyurethane primer layer is first formed on the substrate, then an aluminum oxide layer is plated on the polyurethane primer layer to improve the stability of the aluminum oxide layer, and then a polyurethane topcoat layer is formed on the aluminum oxide layer to protect the The aluminum oxide layer further improves the stability of the aluminum oxide layer, thereby improving the retort resistance of the film.

Optionally, in step S1, the drying temperature of the primer film is 90-100°C, and the drying time is 6-10s; in step S3, the drying temperature of the top-coat film is 100-110°C, and the drying time is 6-10s; step S3 The temperature of medium curing is 50-60℃, and the curing time is 36-60h.

By adopting the above technical solution, curing is carried out after the polyurethane topcoat is formed, and an aluminum oxide layer is plated after the polyurethane bottomcoat is initially formed, so that during the curing process, the polyurethane bottomcoat and the polyurethane topcoat are further formed, and the The connection degree of the aluminum oxide layer is further increased, thereby improving the bonding strength of the polyurethane coating and the aluminum oxide, and improving the structural stability of the film.

Optionally, in step S2, the flow rate of the oxygen gas is 14700-16800 sccm.

By adopting the above technical solution, the rate of forming alumina is controlled in an appropriate range, which is helpful for the deposition of alumina on the polyurethane undercoat layer, thereby forming a densely arranged alumina layer, thereby improving the barrier property of the film.

Optionally, in step S2, the temperature of heating the aluminum wire is 1280-1360° C., the diameter of the aluminum wire is 1.5-1.9 mm, and the wire feeding speed of the aluminum wire is 240-265 mm/min.

By adopting the above technical scheme, the rate of aluminum evaporation is controlled in an appropriate range, and the barrier property of the film is further improved.

Optionally, in step S2, the temperature of heating the aluminum wire is 1320-1340°C, the flow rate of the oxygen is 15200-16300sccm, the diameter of the aluminum wire is 1.7-1.8mm, and the wire feeding speed of the aluminum wire is 245-250mm/min .

By using the above technical solution, the evaporation rate of aluminum and the formation rate of aluminum oxide are simultaneously controlled, so that the compactness of the aluminum oxide layer is improved and the uniformity is better, which is suitable for the aluminum oxide layer with a smaller thickness, thereby improving the light transmittance of the film. .

Optionally, the preparation method of the polyurethane coating liquid is as follows: mixing and stirring the aqueous polyurethane dispersion liquid, the diluent and the crosslinking agent to obtain the polyurethane coating liquid.

Optionally, the preparation method of the polyurethane coating liquid is as follows: mixing and stirring an aqueous polyurethane dispersion liquid, a modified silica sol, a diluent and a crosslinking agent to obtain a polyurethane coating liquid; The preparation method is as follows: mixing silica sol, Span 80, a catalyst and a solvent, adding 2,2'-diphenylmethane diisocyanate dropwise while stirring at 70-76° C., continuing to stir after the dropwise addition, and drying to a temperature of 70-76°C. 65-70% of the volume of the silica sol is filtered to obtain a modified silica sol.

By adopting the above technical scheme, the modification of the silica sol is realized, and part of the moisture and solvent of the modified silica sol is removed by drying the reaction solution, and the stability of the isocyanate group in the modified silica sol is improved, thereby Improve the compatibility of modified silica sol with aqueous polyurethane dispersion.

To sum up, the present application has the following beneficial effects:

1. The application adopts the method of combining the polyurethane primer layer, the aluminum oxide layer and the polyurethane topcoat layer in sequence. The polyurethane primer layer improves the surface smoothness of the substrate and helps the deposition of aluminum oxide. The polyurethane topcoat layer can cover and protect Aluminum oxide layer to improve the strength of the film; with the thickness of the polyurethane topcoat, aluminum oxide layer and polyurethane primer within a specific range, so that the polyurethane topcoat stabilizes the aluminum oxide layer on the polyurethane primer layer and improves oxidation The stability of the aluminum layer enables the aluminum oxide layer to maintain a stable state in the film even at high temperatures, and the polyurethane undercoat and polyurethane topcoat make the two sides of the aluminum oxide layer squeezed, and the aluminum oxide improves the aluminum oxide layer. Density, which not only improves the barrier property, but also improves the structural stability of the film at high temperature, making the film more suitable for the packaging of food that needs to be heated at high temperature.

2. In this application, water-based polyurethane is preferably combined with modified silica sol to improve the mechanical properties of the polyurethane coating, as well as the barrier properties and structural stability of the film.

3. The method of the present application controls the evaporation rate of aluminum and the formation rate of aluminum oxide by limiting the oxygen flow rate, the temperature of heating the aluminum wire, the diameter of the aluminum wire, and the wire feeding speed of the aluminum wire, so that a good barrier is obtained. performance and high temperature stability.

Detailed ways

The present application will be described in further detail below in conjunction with the examples and comparative examples.

The water-based polyurethane was purchased from Anhui Anda Huatai New Material Co., Ltd., model AH-1704-1.

The silica sol was purchased from Yantai Hengxin Chemical Technology Co., Ltd., model THI S-S30.

The manufacturer's models mentioned above are used to support the solution of the present application, so as to be fully disclosed, and are not limited to the listed manufacturer's models.

Preparation example

Preparation Example 1

Polyurethane coating liquid, including the following raw materials:

9kg aqueous polyurethane dispersion, 0.75kg isopropanol, 3.75kg water, 0.2kg aziridine crosslinking agent.

The preparation method of polyurethane coating liquid comprises the following steps:

Aqueous polyurethane dispersion liquid, isopropanol, water and aziridine crosslinking agent are stirred and fully mixed to obtain a polyurethane coating liquid.

Preparation Example 2

Polyurethane coating liquid, including the following raw materials:

9.5kg aqueous polyurethane dispersion, 1kg isopropanol, 5kg water, 0.8kg aziridine crosslinking agent.

The preparation method of polyurethane coating liquid comprises the following steps:

Aqueous polyurethane dispersion liquid, isopropanol, water and aziridine crosslinking agent are stirred and fully mixed to obtain a polyurethane coating liquid.

Preparation Example 3

Polyurethane coating liquid, including the following raw materials:

10kg aqueous polyurethane dispersion, 0.9kg isopropanol, 4.5kg water, 0.5kg aziridine crosslinking agent.

The preparation method of polyurethane coating liquid comprises the following steps:

Aqueous polyurethane dispersion liquid, isopropanol, water and aziridine crosslinking agent are stirred and fully mixed to obtain a polyurethane coating liquid.

Preparation Example 4

Polyurethane coating liquid, including the following raw materials:

10kg aqueous polyurethane dispersion, 2kg silica sol, 0.9kg isopropanol, 4.5kg water, 0.5kg aziridine crosslinking agent.

The preparation method of polyurethane coating liquid comprises the following steps:

Aqueous polyurethane dispersion liquid, silica sol, isopropanol, water and aziridine crosslinking agent are stirred and thoroughly mixed to obtain a polyurethane coating liquid.

Preparation Example 5

Modified silica sol, including the following raw materials:

10kg of silica sol, 0.12kg of 2,2'-diphenylmethane diisocyanate, 1kg of Span 80, 0.8g of dibutyltin diacetate, 10kg of isopropanol.

The preparation method of modified silica sol comprises the following steps:

Silica sol, Span 80 and isopropanol were mixed, and 2,2'-diphenylmethane diisocyanate was added dropwise with stirring at 70°C. The dropwise addition was completed in 30 minutes, and stirring was continued for 2 hours. The resulting reaction solution was put into 60°C. In the oven of , dry until the volume of the reaction solution is 65% of the volume of the original silica sol, and filter to obtain the modified silica sol.

Polyurethane coating liquid, including the following raw materials:

10kg aqueous polyurethane dispersion, 2kg modified silica sol, 0.9kg isopropanol, 4.5kg water, 0.5kg aziridine crosslinking agent.

The preparation method of polyurethane coating liquid comprises the following steps:

Aqueous polyurethane dispersion liquid, modified silica sol, isopropanol, water and aziridine crosslinking agent are stirred and fully mixed to obtain polyurethane coating liquid.

Preparation Example 6

Modified silica sol, including the following raw materials:

10kg of silica sol, 0.22kg of 2,2'-diphenylmethane diisocyanate, 1.5kg of Span 80, 2g of dibutyltin diacetate, 20kg of isopropanol.

The preparation method of modified silica sol comprises the following steps:

Silica sol, Span 80 and isopropanol were mixed, and 2,2'-diphenylmethane diisocyanate was added dropwise with stirring at 76°C. The dropwise addition was completed in 40 minutes, and stirring was continued for 2 hours. The resulting reaction solution was put into 60°C. In the oven of , dry until the volume of the reaction solution is 70% of the volume of the original silica sol, and filter to obtain the modified silica sol.

The polyurethane coating solution includes the following raw materials: 10kg of water-based polyurethane dispersion, 2.5kg of modified silica sol, 0.9kg of isopropanol, 4.5kg of water, and 0.5kg of aziridine crosslinking agent.

The preparation method of polyurethane coating liquid comprises the following steps:

Aqueous polyurethane dispersion liquid, modified silica sol, isopropanol, water and aziridine crosslinking agent are stirred and fully mixed to obtain polyurethane coating liquid.

Example

Example 1

A transparent high-barrier polyester aluminum oxide-coated film, comprising the following layer structures arranged in sequence:

PET film, polyurethane base coat, aluminum oxide layer and polyurethane top coat.

A preparation method of a transparent high-barrier polyester aluminum oxide-coated film, comprising the following steps:

S1. Coat the polyurethane coating solution of Preparation Example 1 on the PET film, the coating amount is 5g/m ² , and then send it to an oven for drying, the drying temperature is 90°C, the path of the PET film in the oven is 10m, and the drying time is 6s , forming a polyurethane primer layer on the PET film, and the thickness of the polyurethane primer layer is 8 μm to obtain a primer film;

S2. Send the aluminum wire and the primer film into the vacuum aluminizing machine, the diameter of the aluminum wire is 1.2mm, the wire feeding speed of the aluminum wire is 210mm/min, and the vacuum is drawn until the vacuum degree of the evaporation is 4×10 ^-4 mbar, Then heat the evaporation boat of the vacuum aluminizer, the heating temperature is 1180 ℃, oxygen is introduced, and the flow rate of oxygen is 13000sccm, and an aluminum oxide layer is formed on the polyurethane primer layer, and the thickness of the aluminum oxide layer is 80 angstroms. coating film;

S3. Coat the polyurethane coating solution on the alumina layer, the coating amount is 5g/m ² , and then send it to the oven to dry, the drying temperature is 100°C, the path of the initial coating film in the oven is 10m, and the drying time is 6s. A polyurethane surface coating is formed on the aluminum layer, and the thickness of the polyurethane surface coating is 8 μm, and then placed in a 50° C. oven for curing for 36 hours to obtain a transparent high-barrier polyester aluminum oxide-coated film.

Example 2 to Example 3

The differences between Examples 2 to 3 and Example 1 are shown in Table 1, and the polyurethane coating solution used in Example 2 is the polyurethane coating solution prepared in Preparation Example 2, and the polyurethane coating solution used in Example 3 is a preparation example. 3. The obtained polyurethane coating solution.

Table 1

Example 4

The difference between this embodiment and Embodiment 3 lies in the difference in step S2. In step S2 of this embodiment, the flow rate of oxygen introduced is 14700 sccm.

Example 5

The difference between this embodiment and Embodiment 3 lies in the difference in step S2. In step S2 of this embodiment, the flow rate of the introduced oxygen is 16800 sccm.

Example 6

The difference between this embodiment and Embodiment 3 lies in the difference in step S2. In step S2 of this embodiment, the temperature of heating the aluminum wire is 1280°C, the diameter of the aluminum wire is 1.5mm, and the wire feeding speed of the aluminum wire is 240mm/ min.

Example 7

The difference between this embodiment and Embodiment 3 lies in the difference in step S2. In step S2 of this embodiment, the temperature of heating the aluminum wire is 1360°C, the diameter of the aluminum wire is 1.9mm, and the wire feeding speed of the aluminum wire is 265mm/ min.

Example 8

The difference between this embodiment and Embodiment 3 lies in the difference in step S2. In step S2 of this embodiment, the diameter of the aluminum wire is 1.7 mm, the wire feeding speed of the aluminum wire is 245 mm/min, and the temperature of heating the aluminum wire is 1320 ℃, the flow rate of the oxygen introduced is 15200sccm.

Example 9

The difference between this embodiment and Embodiment 3 lies in the difference in step S2. In step S2 of this embodiment, the diameter of the aluminum wire is 1.8 mm, the wire feeding speed of the aluminum wire is 250 mm/min, and the temperature of heating the aluminum wire is 1340 ℃, the flow rate of the oxygen introduced is 16300sccm.

Example 10

The difference between this example and Example 9 is that the polyurethane coating solution is different. The polyurethane coating solution used in the S2 step and the S3 step of this example is the polyurethane coating solution prepared in the preparation example 4.

Example 11

The difference between this example and Example 9 is that the polyurethane coating solution is different. The polyurethane coating solution used in the S2 step and the S3 step of this example is the polyurethane coating solution prepared in the preparation example 5.

Example 12

The difference between this example and Example 9 is that the polyurethane coating solution is different. The polyurethane coating solution used in the S2 step and the S3 step of this embodiment is the polyurethane coating solution prepared in the preparation example 6.

Comparative ratio

Comparative Example 1

The difference between this comparative example and Example 3 is that this comparative example is not provided with a polyurethane topcoat.

Comparative Example 2

The difference between this comparative example and Example 3 is that the thickness of the polyurethane primer layer and the thickness of the polyurethane topcoat layer of this comparative example are both 25 μm, and the thickness of the aluminum oxide layer is 60 angstroms.

Comparative Example 3

The difference between this comparative example and Example 3 is that the thickness of the polyurethane primer layer and the thickness of the polyurethane topcoat layer of this comparative example are both 6 μm, and the thickness of the aluminum oxide layer is 220 angstroms.

Comparative Example 4

The difference between this comparative example and Example 3 is that in step S1 of this comparative example, after the polyurethane coating solution is dried, it is put into an oven at 55° C. for curing for 48 hours to form a polyurethane primer layer.

performance test

Retortability test: Heat-sealing the films of Examples 1-12 and Comparative Examples 1-4 into 200mm×120mm pouches, fill them with water to two-thirds of the pouch volume, and then vent and seal them well, and place them in an autoclave. In the middle, boil for 15min, the temperature of the autoclave is 121 ℃ and 135 ℃ respectively, after 15min, decompress and cool to room temperature and take out, check whether there is any abnormal phenomenon of obvious deformation and interlayer peeling of the pouch, and record the results in Table 2 .

Oxygen barrier property test: According to ASTM D 3985, the oxygen permeability of the films of Examples 1-12 and Comparative Examples 1-4 was tested, and the test results are shown in Table 2.

Water vapor barrier property: According to ASTM F 1249, the moisture permeability of the films of Examples 1-12 and Comparative Examples 1-4 was tested, and the test results are shown in Table 2.

Light transmittance test: According to GB/T 2410-2008 "Determination of light transmittance and haze of transparent plastics", the light transmittance of the films of Examples 1-12 and Comparative Examples 1-4 was tested, and the test results are shown in the table 2 shown.

Table 2

The standard value of oxygen permeability is ≤0.5cc/m ² .day, the standard value of moisture permeability is ≤1.0cc/m ² .day, and the standard value of light transmittance is ≥88%.

According to Table 2, combined with Example 3 and Comparative Example 1, it can be seen that the polyurethane surface coating is arranged on the alumina layer, which can improve the degree of protection of the alumina layer, thereby maintaining the stability of the entire film, cooking at a high temperature of 121 ° C The film can still maintain good structural stability, and the oxygen permeability and moisture permeability of the film are significantly reduced and meet the requirements of the standard value.

Combining Example 3 with Comparative Examples 2-3, it can be seen that when the polyurethane topcoat, the aluminum oxide layer and the polyurethane undercoat meet a specific thickness, due to the improved stability of the aluminum oxide layer, the film can be heated at a high temperature of 121 ° C. The structural stability in the state is good, and it has good oxygen barrier properties and water vapor barrier properties at the same time.

Combining Example 3 and Comparative Example 4, it can be seen that if the polyurethane primer layer is initially formed on the substrate and then the aluminum oxide layer is plated, the film has higher stability under high temperature cooking at 121°C.

Combining Example 3 and Example 4-5, it can be seen that when the oxygen flow rate is limited in the range of 14700-16800 sccm, both the oxygen barrier properties and the water vapor barrier properties are improved to a certain extent, indicating that controlling the formation rate of alumina is helpful. It is used to improve the compactness of the alumina layer, thereby improving the oxygen barrier properties and water vapor barrier properties.

Combining Example 3 and Example 6-7, it can be seen that when the temperature for heating the aluminum wire is limited to 1280-1360 ° C, the diameter of the aluminum wire is 1.5-1.9 mm, and the wire feeding speed of the aluminum wire is in the range of 240-265 mm/min When , the oxygen barrier properties and water vapor barrier properties are improved to a certain extent, indicating that controlling the evaporation rate of aluminum can also improve the oxygen barrier properties and water vapor barrier properties.

Combining Example 3 with Examples 8-9, it can be seen that when the oxygen flow rate, the temperature of heating the aluminum wire, the diameter of the aluminum wire, and the wire feeding speed of the aluminum wire are further limited at the same time, the evaporation rate of aluminum and the rate of aluminum oxide are simultaneously controlled. When the formation rate is within a specific range, not only the oxygen barrier properties and water vapor barrier properties of the film are improved, but also the uniformity of the alumina layer may be further improved, so that the light transmittance of the film is improved.

Combining Example 9 and Example 10, it can be seen that when unmodified silica sol is added to the polyurethane coating solution, the oxygen barrier properties and water vapor barrier properties of the film are not improved, and the light transmittance is reduced to some extent. ; It can be seen in combination with Example 9 and Example 11-12 that when the modified silica sol is added to the polyurethane coating solution, not only the oxygen barrier properties and water vapor barrier properties are improved, but the light transmittance is higher than that of Example 10, and The film can still maintain good structural stability under high temperature cooking at 135 °C.

This specific embodiment is only an explanation of the application, and it does not limit the application. Those skilled in the art can make modifications to the embodiment without creative contribution as needed after reading this specification, but as long as the rights of the application are All claims are protected by patent law.

Claims (6)

1. The transparent high-barrier polyester aluminum oxide-plated film is characterized by comprising a base material, a polyurethane bottom coating, an aluminum oxide layer and a polyurethane top coating which are sequentially arranged, wherein the thickness of the polyurethane bottom coating and the thickness of the polyurethane top coating are both 8-15 micrometers, the thickness of the aluminum oxide layer is 80-140 angstroms, and the polyurethane bottom coating and the polyurethane top coating are both formed by drying polyurethane coating liquid;

a transparent high-barrier polyester aluminum oxide-plated film comprises the following steps:

s1, coating a polyurethane coating liquid on a substrate, drying, and forming a polyurethane bottom coating on the substrate to obtain a bottom coating film;

s2, feeding the primary coating film into a vacuum aluminizing device, vacuumizing, heating an aluminum wire, introducing oxygen, and forming an aluminum oxide layer on the polyurethane primary coating to obtain a primary coating film;

s3, coating polyurethane coating liquid on the aluminum oxide layer, drying, forming a polyurethane surface coating on the aluminum oxide layer, and curing to obtain a transparent high-barrier polyester aluminum oxide-plated film;

in the step S2, the temperature of the heated aluminum wire is 1320-1340 ℃, the flow rate of the introduced oxygen is 15200-16300 sccm, the diameter of the aluminum wire is 1.7-1.8 mm, and the wire feeding speed of the aluminum wire is 245-250 mm/min.

2. The transparent high-barrier polyester aluminum oxide-plated film according to claim 1, wherein: the polyurethane coating liquid comprises the following raw materials in parts by weight: 90-100 parts of aqueous polyurethane dispersion liquid, 45-60 parts of diluent and 2-8 parts of cross-linking agent.

3. The transparent high-barrier polyester aluminum oxide-plated film according to claim 2, wherein: the polyurethane coating liquid comprises the following raw materials, by weight, 20-25 parts of modified silica sol, wherein the modified silica sol is prepared from raw materials including the silica sol, 2 '-diphenylmethane diisocyanate, span 80, a catalyst and a solvent, and the weight ratio of the silica sol, the 2,2' -diphenylmethane diisocyanate, the span 80, the catalyst and the solvent is 10 (0.12-0.22): (1-1.5): 0.0008-0.002): 10-20.

4. The transparent high-barrier polyester aluminum oxide-plated film according to claim 1, wherein: s1, drying the bottom coating film at 90-100 ℃ for 6-10S; s3, drying the surface coating film at 100-110 ℃ for 6-10S; in the step S3, the curing temperature is 50-60 ℃, and the curing time is 36-60 hours.

5. The transparent high-barrier polyester aluminum oxide-plated film according to claim 1, wherein: the preparation method of the polyurethane coating liquid comprises the following steps: and mixing and stirring the aqueous polyurethane dispersion liquid, the diluent and the cross-linking agent to obtain the polyurethane coating liquid.

6. The transparent high-barrier polyester aluminum oxide-plated film according to claim 1, wherein: the preparation method of the polyurethane coating liquid comprises the following steps: mixing and stirring the aqueous polyurethane dispersion liquid, the modified silica sol, the diluent and the cross-linking agent to obtain a polyurethane coating liquid; the preparation method of the modified silica sol comprises the following steps: mixing the silica sol, span 80, a catalyst and a solvent, dropwise adding 2,2' -diphenylmethane diisocyanate while stirring at 70-76 ℃, continuously stirring after dropwise adding, drying to 65-70% of the original volume of the silica sol, and filtering to obtain the modified silica sol.