PP coating applied to composite current collector seed layer and preparation method thereof

Abstract

The application discloses a PP film applied to a composite current collector seed layer and a preparation method thereof, and relates to the field of current collector materials. The PP film comprises a PP film, a first adhesion-increasing layer, a second adhesion-increasing layer, a first aluminum oxide plating layer and a second aluminum oxide plating layer. The materials of the first adhesion-increasing layer and the second adhesion-increasing layer are UV light-cured acrylate coatings, which are prepared from 4-polyester acrylate resins, 2-epoxy acrylate resins, 6-aliphatic polyurethane acrylates, 4-aliphatic polyurethane acrylates, single-branch UV monomers, double-branch UV monomers, triple-branch UV monomers, organic silicon UV monomers, photoinitiators, leveling agents and a remainder of 2-aliphatic polyurethane acrylates in a specific ratio. The UV light-cured acrylate coating can improve the bonding force between the two aluminum oxide plating layers and the PP film, improve the mechanical strength of the PP film and improve the stability of the composite current collector.

Description

Technical Field

[0001] This application relates to the field of current collector materials, and in particular to a PP coating applied to a composite current collector seed layer and its preparation method. Background Technology

[0002] Composite current collectors are a new type of current collector material that employs a "sandwich structure." The middle layer is a polymer layer, such as PET, PP, or PI, while the two sides are conductive layers (metal layers). Currently, PET-based film is the most commonly used material for the polymer layer in the composite current collector industry because it has superior tensile strength and thermal stability compared to PP. Furthermore, PET is a polar polymer with higher bonding strength to metals and metal oxides. However, PET-based film also has some significant shortcomings in practical applications. For example, PET-based film has relatively poor weather resistance; its performance is prone to degradation when exposed to ultraviolet light or high temperatures for extended periods, thus affecting the overall performance and service life of the composite current collector.

[0003] In comparison, while PP material has slightly lower tensile strength and thermal stability than PET, it possesses excellent weather resistance and chemical stability, maintaining stable performance even in harsh environments. Furthermore, PP has a lower surface energy, making it less prone to surface defects, which is beneficial for preparing high-quality composite current collectors. However, PP is a non-polar material, resulting in poor interfacial adhesion between the coating and the PP material, which to some extent limits its application in composite current collectors. Summary of the Invention

[0004] To improve the problem of poor interfacial adhesion between the coating and PP material in related technologies, this application provides a PP coating applied to the seed layer of a composite current collector and its preparation method.

[0005] Firstly, this application provides a PP coating for use in the seed layer of a composite current collector, employing the following technical solution:

[0006] A PP coating applied to a composite current collector seed layer includes a PP film, a first adhesive layer and a second adhesive layer disposed on two opposite surfaces of the PP film, a first alumina coating disposed on the side of the first adhesive layer away from the PP film, and a second alumina coating disposed on the side of the second adhesive layer away from the PP film.

[0007] The first and second tackifying layers are both made of UV-curable acrylate coatings. The UV-curable acrylate coatings are prepared from 4-8 wt% of 4-functional polyester acrylate resin, 4-6 wt% of 2-functional epoxy acrylate resin, 8-12 wt% of 6-functional aliphatic polyurethane acrylate, 15-20 wt% of 4-functional aliphatic polyurethane acrylate, 2-4 wt% of monofunctional UV monomer, 8-10 wt% of difunctional UV monomer, 6-8 wt% of trifunctional UV monomer, 4-6 wt% of silicone UV monomer, 8-10 wt% of photoinitiator, 1-1.5 wt% of leveling agent, and the balance of 2-functional aliphatic polyurethane acrylate.

[0008] In this application, before vapor deposition of alumina, a UV-curable acrylate coating is first applied to the PP film to form a first tackifying layer and a second tackifying layer. Then, alumina is vapor deposited onto the surfaces of the first and second tackifying layers. The UV-curable acrylate coating in this application is prepared from a specific ratio of tetrafunctional polyester acrylate resin, difunctional epoxy acrylate resin, hexafunctional aliphatic polyurethane acrylate, tetrafunctional aliphatic polyurethane acrylate, monofunctional UV monomer, difunctional UV monomer, trifunctional UV monomer, silicone UV monomer, and difunctional aliphatic polyurethane acrylate. Through the interaction of these components, a coating with moderate viscosity and a curing energy of 40-50 mJ / cm² is obtained. 2 This UV-curable acrylic coating exhibits high tensile strength and good flexibility. It enhances the adhesion between the two alumina coating layers and the PP film, addressing the poor adhesion between the alumina coating and the PP film in existing PP coatings. Furthermore, the low curing energy of this UV-curable acrylic coating ensures that it does not adversely affect the mechanical properties of the PP film during the curing process. Moreover, the first and second tackifying layers formed by this UV-curable acrylic coating combine good tensile strength and toughness, which is beneficial for improving the mechanical strength of the PP film and enhancing the stability of the composite current collector.

[0009] In some specific embodiments, the difunctional UV monomer is a composition of dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and propoxylated neopentyl glycol diacrylate in a weight ratio of (1-2):(4-6):(3-4).

[0010] In this application, the difunctional UV monomer is further preferably a composition of dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and propoxylated neopentyl glycol diacrylate in a weight ratio of (1-2):(4-6):(3-4), which is beneficial to further improve the adhesion of the alumina coating and can improve the tensile strength of the PP coating while taking into account the toughness of the PP coating.

[0011] In some specific embodiments, the trifunctional UV monomer is at least one of ethoxylated trimethylolpropane triacrylate and propoxylated trimethylolpropane triacrylate.

[0012] In this application, the preferred trifunctional UV monomers are ethoxylated trimethylolpropane triacrylate and propoxylated trimethylolpropane triacrylate. Compared with trimethylolpropane triacrylate, the use of ethoxylated trimethylolpropane triacrylate or propoxylated trimethylolpropane triacrylate as the trifunctional UV monomer is beneficial to further improve the adhesion of the alumina coating, and can also further improve the toughness of the PP coating, thereby improving the overall quality and performance of the PP coating.

[0013] In some specific embodiments, the monofunctional UV monomer is at least one of 2-(2-ethoxyethoxy)ethyl acrylate and isobornyl acrylate.

[0014] More preferably, the monofunctional UV monomer is 2-(2-ethoxyethoxy)ethyl acrylate.

[0015] Compared with isoborneol acrylate as a monofunctional UV monomer, the use of 2-(2-ethoxyethoxy)ethyl acrylate as a monofunctional UV monomer is beneficial to further improve the flexibility of UV-cured acrylic coatings. This allows the first and second tackifying layers to have good tensile strength while reducing problems such as alumina coating peeling due to stress concentration. It further enhances the adhesion between the alumina coating and the PP film, thereby improving the overall quality and performance of the PP coating.

[0016] In some specific embodiments, the organosilicon UV monomer is γ-methacryloyloxypropyltrimethoxysilane.

[0017] In this application, the organosilicon UV monomer is γ-methacryloxypropyltrimethoxysilane. By utilizing the coupling effect between γ-methacryloxypropyltrimethoxysilane and the alumina coating, the adhesion of the alumina coating can be further improved, thereby improving the overall quality and performance of the PP coating.

[0018] In some specific embodiments, the photoinitiator is at least one of photoinitiator 1173 and photoinitiator 184.

[0019] In some specific embodiments, the surfaces of the PP film that are bonded to the first and second adhesive layers are subjected to plasma treatment.

[0020] In this application, the surface of the PP film that is bonded to the first and second tackifying layers is subjected to plasma treatment to change the microstructure of the PP film surface and increase its surface energy, so that the UV-curable acrylic coating can better wet and adhere to the PP film, thereby improving the bonding strength between the PP film and the first and second tackifying layers and further enhancing the overall stability of the PP coating.

[0021] In some specific embodiments, the thickness of the PP film is 7-8 μm, the thickness of the first and second tackifying layers is 4-8 μm, and the thickness of the first and second alumina coatings is 8-12 nm.

[0022] Secondly, the method for preparing a PP coating applied to a composite current collector seed layer provided in this application adopts the following technical solution:

[0023] A method for preparing a PP coating for use in a composite current collector seed layer includes the following steps:

[0024] A UV-curable acrylic coating is uniformly sprayed onto one side of a PP film. After UV curing, the first tack layer is formed.

[0025] Vacuum vapor deposition of alumina is performed on the first adhesion-enhancing layer to form a first alumina coating;

[0026] A UV-curable acrylic coating is uniformly sprayed onto the side of the PP film opposite to the first tackifying layer. After UV curing, a second tackifying layer is formed.

[0027] Vacuum evaporation of alumina is performed on the second tackifying layer to form a second alumina coating, resulting in a PP coating.

[0028] In some specific implementations, during vacuum evaporation of alumina, the aluminum wire feeding speed is 170-230 mm / min, and the oxygen flow rate is 8700-10700 sccm.

[0029] In this application, during vacuum evaporation of alumina, the wire feeding speed of the aluminum wire is controlled at 170-230 mm / min, and the oxygen flow rate is controlled at 8700-10700 sccm. Such parameter settings can ensure that the alumina coating is uniformly and densely deposited on the surfaces of the first and second tackifying layers, giving the alumina coating a good crystalline structure and physicochemical properties, further improving the bonding force between the alumina coating and the tackifying layer, and ensuring that the PP coating has stable performance and a long service life in subsequent use.

[0030] In some specific embodiments, a pre-treatment step of plasma treatment of the PP film is also included. The plasma treatment power is 8-15kw, and the working gas is argon and oxygen, with a flow ratio of argon to oxygen of (3-4):1.

[0031] In this application, controlling the appropriate plasma processing power can ensure the processing effect while avoiding damage to the PP film. Argon and oxygen are selected as working gases, and the flow ratio of argon and oxygen is controlled within the range of (3-4):1, which can effectively improve the microstructure of the PP film surface, increase the surface roughness, and improve the surface energy. This allows the subsequently coated UV-cured acrylic coating to better bond with the PP film, enhance the adhesion between the first and second tackifying layers and the PP film, and thus improve the overall quality and performance of the PP coating.

[0032] In summary, this application includes at least the following beneficial technical effects:

[0033] (1) In this application, before vapor deposition of alumina, a UV-curable acrylate coating is first applied to the PP film to form a first tackifying layer and a second tackifying layer, and then alumina is vapor deposited on the surfaces of the first tackifying layer and the second tackifying layer. The UV-curable acrylate coating in this application is prepared from a specific ratio of tetrafunctional polyester acrylate resin, difunctional epoxy acrylate resin, hexafunctional aliphatic polyurethane acrylate, tetrafunctional aliphatic polyurethane acrylate, monofunctional UV monomer, difunctional UV monomer, trifunctional UV monomer, organosilicon UV monomer, and difunctional aliphatic polyurethane acrylate. Through the interaction of the various components, a coating with moderate viscosity and a curing energy of 40-50 mJ / cm² is obtained. 2 This UV-curable acrylic coating exhibits high tensile strength and good flexibility. It enhances the adhesion between the two alumina coating layers and the PP film, addressing the poor adhesion between the alumina coating and the PP film in existing PP coatings. Furthermore, the low curing energy of this UV-curable acrylic coating ensures that it does not adversely affect the mechanical properties of the PP film during the curing process. Moreover, the first and second tackifying layers formed by this UV-curable acrylic coating combine good tensile strength and toughness, which is beneficial for improving the mechanical strength of the PP film and enhancing the stability of the composite current collector.

[0034] (2) In this application, the difunctional UV monomer is further preferably a composition of dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate and propoxylated neopentyl glycol diacrylate in a weight ratio of (1-2):(4-6):(3-4), which is beneficial to further improve the adhesion of the alumina coating and can improve the tensile strength of the PP coating while taking into account the toughness of the PP coating. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a PP coating applied to the seed layer of a composite current collector according to this application.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. PP film; 2. First tackifying layer; 3. Second tackifying layer; 4. First alumina coating; 5. Second alumina coating. Detailed Implementation

[0038] The following specific experiments further illustrate this application.

[0039] Preparation Example

[0040]

Preparation Example 1

[0041] A UV-curable acrylate coating is prepared from 4 wt% of 4-functional polyester acrylate resin DH-2213, 6 wt% of 2-functional epoxy acrylate resin DH-151, 8 wt% of 6-functional aliphatic polyurethane acrylate DH-610, 20 wt% of 4-functional aliphatic polyurethane acrylate DH-4081, 2 wt% of ethyl 2-(2-ethoxyethoxy)acrylate, 10 wt% of difunctional UV monomer, 6 wt% of ethoxylated trimethylolpropane triacrylate, 4 wt% of γ-methacryloyloxypropyltrimethoxysilane, 8 wt% photoinitiator 1173, 1 wt% of BYK3510 leveling agent, and the balance being 2-functional aliphatic polyurethane acrylate DH-320.

[0042] The difunctional UV monomer is a composition of dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and propoxylated neopentyl glycol diacrylate in a weight ratio of 2:4:4; the 4-functional polyester acrylate resin, 2-functional epoxy acrylate resin, 6-functional aliphatic polyurethane acrylate, 4-functional aliphatic polyurethane acrylate, and 2-functional aliphatic polyurethane acrylate are all products of Nanxiong Dinghao Photochemical Technology Co., Ltd.

[0043]

Preparation Example 2

[0044] A UV-curable acrylate coating is prepared from 8 wt% of 4-functional polyester acrylate resin DH-2213, 4 wt% of 2-functional epoxy acrylate resin DH-152, 12 wt% of 6-functional aliphatic polyurethane acrylate DH-608, 15 wt% of 4-functional aliphatic polyurethane acrylate DH-4081, 4 wt% isobornyl acrylate, 8 wt% difunctional UV monomer, 8 wt% ethoxylated trimethylolpropane triacrylate, 6 wt% γ-methacryloyloxypropyltrimethoxysilane, 10 wt% photoinitiator 184, 1.5 wt% BYK3510 leveling agent, and the balance being 2-functional aliphatic polyurethane acrylate DH-320.

[0045] The difunctional UV monomer is a composition of dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and propoxylated neopentyl glycol diacrylate in a weight ratio of 1:6:3; the 4-functional polyester acrylate resin, 2-functional epoxy acrylate resin, 6-functional aliphatic polyurethane acrylate, 4-functional aliphatic polyurethane acrylate, and 2-functional aliphatic polyurethane acrylate are all products of Nanxiong Dinghao Photochemical Technology Co., Ltd.

[0046]

Preparation Example 3

[0047] A UV-curable acrylate coating differs from [Preparation Example 1] in that the difunctional UV monomer is a composition of dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and propoxylated neopentyl glycol diacrylate in a weight ratio of 4:4:2.

[0048]

Preparation Example 4

[0049] A UV-curable acrylic coating differs from [Preparation Example 1] in that the difunctional UV monomer is a composition of dipropylene glycol diacrylate and ethoxylated bisphenol A diacrylate in a weight ratio of 6:4.

[0050]

Preparation Example 5

[0051] A UV-curable acrylic coating differs from [Preparation Example 1] in that the difunctional UV monomer is a composition of dipropylene glycol diacrylate and propoxylated neopentyl glycol diacrylate in a weight ratio of 6:4.

[0052]

Preparation Example 6

[0053] A UV-curable acrylic coating differs from [Preparation Example 1] in that the difunctional UV monomer is a composition of ethoxylated bisphenol A diacrylate and propoxylated neopentyl glycol diacrylate in a weight ratio of 4:6.

[0054] Comparative preparation example

[0055]

Comparative Preparation Example 1

[0056] A UV-curable acrylate coating differs from [Preparation Example 1] in that the proportions of its components are different. In this comparative example, the UV-curable acrylate coating is prepared from 12 wt% of 4-functional polyester acrylate resin DH-2213, 8 wt% of 2-functional epoxy acrylate resin DH-151, 1 wt% of 6-functional aliphatic polyurethane acrylate DH-610, 10 wt% of 4-functional aliphatic polyurethane acrylate DH-4081, 8 wt% of 2-(2-ethoxyethoxy)ethyl acrylate, 2 wt% of difunctional UV monomer, 2 wt% of ethoxylated trimethylolpropane triacrylate, 4 wt% of γ-methacryloyloxypropyltrimethoxysilane, 8 wt% photoinitiator 1173, 1 wt% of BYK3510 leveling agent, and the balance being 2-functional aliphatic polyurethane acrylate DH-320.

[0057] The difunctional UV monomer is a composition of dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and propoxylated neopentyl glycol diacrylate in a weight ratio of 2:4:4; the 4-functional polyester acrylate resin, 2-functional epoxy acrylate resin, 6-functional aliphatic polyurethane acrylate, 4-functional aliphatic polyurethane acrylate, and 2-functional aliphatic polyurethane acrylate are all products of Nanxiong Dinghao Photochemical Technology Co., Ltd.

[0058] Tests showed that the curing energy of the UV-curable acrylic coatings in Preparation Examples 1-6 were all between 45-50 mJ / cm². 2 Within the specified range, the curing energy of the UV-curable acrylic coating in [Comparative Preparation Example 1] is 60-65 mJ / cm². 2 Within the range. Example

[0059]

Example 1

[0060] A PP coating applied to the seed layer of a composite current collector, as shown in the reference. Figure 1 It includes a PP film 1, a first adhesive layer 2 and a second adhesive layer 3 disposed on two opposite surfaces of the PP film 1, a first alumina coating 4 disposed on the side of the first adhesive layer 2 away from the PP film 1, and a second alumina coating 5 disposed on the side of the second adhesive layer 3 away from the PP film 1.

[0061] In this embodiment, a method for preparing a PP coating applied to a composite current collector seed layer includes the following steps:

[0062] S0. Plasma treatment is performed on the two surfaces of a PP film 1 with a thickness of 7.8 μm. The plasma treatment power is 10 kW, and the working gases are argon and oxygen. The flow rate of argon is 15 sccm and the flow rate of oxygen is 5 sccm to obtain the plasma-treated PP film.

[0063] S1. Uniformly spray the UV-curable acrylic coating from Preparation Example 1 onto one of the plasma-treated surfaces of the plasma-treated PP film, and then cure it with a curing energy of 50 mJ / cm². 2 A first adhesive layer 2 is formed, the thickness of which is 5μm;

[0064] S2. Vacuum evaporation of aluminum oxide is performed on the first tackifying layer 2. During vacuum evaporation of aluminum oxide, the wire feeding speed of the aluminum wire is 200 mm / min, the oxygen flow rate is 10000 sccm, and a first aluminum oxide coating layer 4 with a thickness of 10 nm is formed.

[0065] S3. Uniformly spray the UV-curable acrylic coating from Preparation Example 1 onto the plasma-treated PP film on the side opposite to the first tackifying layer 2, and then cure it with a curing energy of 50 mJ / cm². 2 A second tackifying layer 3 is formed, the thickness of which is 5 μm;

[0066] S4. Vacuum evaporation of alumina is performed on the second tackifying layer 3. During vacuum evaporation of alumina, the wire feeding speed of the aluminum wire is 200 mm / min, and the oxygen flow rate is 10000 sccm, forming a second alumina coating 5 with a thickness of 10 nm, thus obtaining a PP coating.

[0067]

Example 2

[0068] A PP coating applied to the seed layer of a composite current collector, as shown in the reference. Figure 1 It includes a PP film 1, a first adhesive layer 2 and a second adhesive layer 3 disposed on two opposite surfaces of the PP film 1, a first alumina coating 4 disposed on the side of the first adhesive layer 2 away from the PP film 1, and a second alumina coating 5 disposed on the side of the second adhesive layer 3 away from the PP film 1.

[0069] In this embodiment, a method for preparing a PP coating applied to a composite current collector seed layer includes the following steps:

[0070] S0. Plasma treatment is performed on the two surfaces of a PP film 1 with a thickness of 7.8 μm. The plasma treatment power is 10 kW, and the working gases are argon and oxygen. The flow rate of argon is 15 sccm and the flow rate of oxygen is 5 sccm to obtain the plasma-treated PP film.

[0071] S1. Uniformly spray the UV-curable acrylic coating from Preparation Example 2 onto one of the plasma-treated surfaces of the plasma-treated PP film, and then cure it with a curing energy of 50 mJ / cm². 2 A first adhesive layer 2 is formed, the thickness of which is 5μm;

[0072] S2. Vacuum evaporation of aluminum oxide is performed on the first tackifying layer 2. During vacuum evaporation of aluminum oxide, the wire feeding speed of the aluminum wire is 200 mm / min, the oxygen flow rate is 10000 sccm, and a first aluminum oxide coating layer 4 with a thickness of 10 nm is formed.

[0073] S3. Uniformly spray the UV-curable acrylic coating from Preparation Example 2 onto the plasma-treated PP film on the side opposite to the first tackifying layer. Then, cure the coating using UV light at an energy of 50 mJ / cm². 2 A second tackifying layer 3 is formed, the thickness of which is 5 μm;

[0074] S4. Vacuum evaporation of alumina is performed on the second tackifying layer 3. During vacuum evaporation of alumina, the wire feeding speed of the aluminum wire is 200 mm / min, and the oxygen flow rate is 10000 sccm, forming a second alumina coating 5 with a thickness of 10 nm, thus obtaining a PP coating.

[0075]

Example 3

[0076] A PP coating applied to the seed layer of a composite current collector differs from that in [Example 1] in that the UV-curable acrylic coating is replaced by the UV-curable acrylic coating in [Preparation Example 3].

[0077]

Example 4

[0078] A PP coating applied to the seed layer of a composite current collector differs from that in [Example 1] in that the UV-curable acrylic coating is replaced by the UV-curable acrylic coating in [Preparation Example 4].

[0079]

Example 5

[0080] A PP coating applied to the seed layer of a composite current collector differs from that in [Example 1] in that the UV-curable acrylic coating is replaced by the UV-curable acrylic coating in [Preparation Example 5].

[0081]

Example 6

[0082] A PP coating applied to the seed layer of a composite current collector differs from that in [Example 1] in that the UV-curable acrylic coating is replaced by the UV-curable acrylic coating in [Preparation Example 6].

[0083] Comparative Example

[0084] Comparative Example 1

[0085] A PP coating applied to the seed layer of a composite current collector differs from that in [Example 1] in that the UV-curable acrylic coating in steps S1 and S3 is replaced by the UV-curable acrylic coating in [Comparative Preparation Example 1], and the curing energy during the curing process is 65 mJ / cm². 2 .

[0086] Comparative Example 2

[0087] A PP coating applied to a composite current collector seed layer includes a PP film, a first alumina coating on one side of the PP film, and a second alumina coating on the side of the PP film opposite to the first alumina coating.

[0088] In this comparative example, a method for preparing a PP coating applied to a composite current collector seed layer includes the following steps:

[0089] S1. Vacuum evaporation of aluminum oxide is performed on one side of a PP film with a thickness of 7.8μm. During vacuum evaporation of aluminum oxide, the wire feeding speed of the aluminum wire is 200mm / min, the oxygen flow rate is 10000sccm, and a first aluminum oxide coating with a thickness of 10nm is formed.

[0090] S2. Vacuum evaporation of aluminum oxide is performed on the side of the PP film opposite to the first aluminum oxide coating. During vacuum evaporation of aluminum oxide, the wire feeding speed of the aluminum wire is 200 mm / min, and the oxygen flow rate is 10000 sccm, forming a second aluminum oxide coating with a thickness of 10 nm, thus obtaining the PP coating.

[0091] Comparative Example 3

[0092] A PP coating applied to a composite current collector seed layer includes a PP film, a first alumina coating on one side of the PP film, and a second alumina coating on the side of the PP film opposite to the first alumina coating.

[0093] In this comparative example, a method for preparing a PP coating applied to a composite current collector seed layer includes the following steps:

[0094] S0. Plasma treatment is performed on both surfaces of a 7.8 μm thick PP film. The plasma treatment power is 10 kW, and the working gases are argon and oxygen. The flow rate of argon is 15 sccm and the flow rate of oxygen is 5 sccm, resulting in a plasma-treated PP film.

[0095] S1. Vacuum evaporation of alumina is performed on one of the plasma-treated surfaces of the plasma-treated PP film. During vacuum evaporation of alumina, the wire feeding speed of the aluminum wire is 200 mm / min, the oxygen flow rate is 10000 sccm, and a first alumina coating with a thickness of 10 nm is formed.

[0096] S2. Vacuum evaporation of alumina is performed on the plasma-treated PP film on the other plasma-treated surface away from the first adhesive layer. During vacuum evaporation of alumina, the wire feeding speed of the aluminum wire is 200 mm / min, and the oxygen flow rate is 10000 sccm, forming a second alumina coating with a thickness of 10 nm, thus obtaining the PP film.

[0097] Performance testing

[0098] Alumina coating adhesion: Referring to QB / T 2358-1998 "Test Method for Heat Seal Strength of Plastic Film Packaging Bags", the heat seal layer of EAA film was heat-sealed with the alumina coating of PP film at a heat seal temperature of 125℃, a pressure of 0.25MPa, and a heat seal time of 1.8s. Then, the alumina coating was peeled off from the PP film using a tensile testing machine to obtain adhesion data, and the results are recorded in Table 2 below.

[0099] Tensile strength: Tested according to GB / T 1040.3-2006, with a tensile speed of 100 mm / min and a test environment of 23±2℃ and 50±10% RH.

[0100] Elongation at break: Tested according to GB / T 1040.3-2006, with a tensile speed of 100 mm / min and a test environment of 23±2℃ and 50±10% RH.

[0101] Table 1

[0102]

[0103] Table 2

[0104]

[0105] Based on the test data in Example 1, Comparative Examples 1-3, and Table 1-2, it can be seen that plasma treatment of PP film can improve the adhesion between the alumina coating and the PP film, but the improvement is limited. Adding an adhesion-enhancing layer made of UV-curable acrylic coating composed of specific raw materials between the PP film and the alumina coating can effectively improve the adhesion between the alumina coating and the PP film. At the same time, it can further improve the tensile strength and elongation at break of the PP coating.

[0106] Based on the test data in Examples 1 and 3-6 and Table 1-2, it can be seen that in this application, the difunctional UV monomer is further preferably a composition of dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and propoxylated neopentyl glycol diacrylate in a weight ratio of (1-2):(4-6):(3-4), which is beneficial to further improve the adhesion of the alumina coating and can improve the tensile strength of the PP coating while taking into account the toughness of the PP coating.

[0107] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A PP coating applied to a composite current collector seed layer, characterized in that: The coating comprises a PP film, a first tackifying layer and a second tackifying layer disposed on two opposite surfaces of the PP film, a first alumina coating disposed on the side of the first tackifying layer opposite to the PP film, and a second alumina coating disposed on the side of the second tackifying layer opposite to the PP film. Both the first and second tackifying layers are made of UV-curable acrylate coatings, which are prepared from 4-8 wt% 4-functional polyester acrylate resin, 4-6 wt% 2-functional epoxy acrylate resin, 8-12 wt% 6-functional aliphatic polyurethane acrylate, 15-20 wt% 4-functional aliphatic polyurethane acrylate, 2-4 wt% monofunctional UV monomer, 8-10 wt% difunctional UV monomer, 6-8 wt% trifunctional UV monomer, 4-6 wt% silicone UV monomer, 8-10 wt% photoinitiator, 1-1.5 wt% leveling agent, and the balance being 2-functional aliphatic polyurethane acrylate. The monofunctional UV monomer is at least one of 2-(2-ethoxyethoxy)ethyl acrylate and isobornyl acrylate; The difunctional UV monomer is a composition of dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and propoxylated neopentyl glycol diacrylate in a weight ratio of (1-2):(4-6):(3-4); The trifunctional UV monomer is at least one of ethoxylated trimethylolpropane triacrylate and propoxylated trimethylolpropane triacrylate; The organosilicon UV monomer used is γ-methacryloyloxypropyltrimethoxysilane.

2. The PP coating applied to the seed layer of a composite current collector according to claim 1, characterized in that: The photoinitiator is at least one of photoinitiator 1173 and photoinitiator 184.

3. A PP coating applied to a composite current collector seed layer according to any one of claims 1-2, characterized in that: The surfaces of the PP film that are bonded to the first and second adhesive layers are subjected to plasma treatment.

4. A method for preparing a PP coating applied to a composite current collector seed layer, used to prepare the PP coating applied to a composite current collector seed layer as described in any one of claims 1-2, characterized in that, Includes the following steps: A UV-curable acrylic coating is uniformly sprayed onto one side of a PP film. After UV curing, a first tack layer is formed. Alumina is then vacuum-deposited onto the first tack layer to form a first alumina coating. A UV-curable acrylic coating is uniformly sprayed onto the side of the PP film opposite to the first tackifying layer. After UV curing, a second tackifying layer is formed. Alumina is then vacuum-deposited onto the second tackifying layer to form a second alumina coating, thus obtaining a PP film.

5. The method for preparing a PP coating applied to a composite current collector seed layer according to claim 4, characterized in that: During vacuum evaporation of alumina, the aluminum wire feeding speed is 170-230 mm / min, and the oxygen flow rate is 8700-10700 sccm.

6. The method for preparing a PP coating applied to a composite current collector seed layer according to claim 4, characterized in that: It also includes a pre-treatment step of plasma treatment of PP film, with a plasma treatment power of 8-15kw, and working gases of argon and oxygen, with a flow ratio of argon to oxygen of (3-4):1.

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