Adhesive, preparation method and application thereof, polyacrylic acid adhesive film and application thereof

Abstract

The invention belongs to the technical field of power batteries, and particularly relates to an adhesive, a preparation method and application of the adhesive, a polyacrylic acid adhesive film and application of the polyacrylic acid adhesive film. The invention provides an adhesive. The adhesive is prepared from the following raw materials: polyacrylate and a photoinitiator, the polyacrylate is prepared from the following raw materials: a soft monomer, a hard monomer, a functional monomer, acrylate-based hepta-epoxy POSS (Polyhedral Oligomeric Silsesquioxane) and an initiator; the acrylate-based hepta-epoxy POSS has a structure as shown in the specification. According to the invention, the acrylate obtained from the soft monomer, the hard monomer and the functional monomer has the characteristic of low surface tension and can improve the wettability of a resin system to the aluminum surface, and the rapid polymerization initiated by cations can lock the good infiltration state and enhance the mechanical anchoring effect, so that the adhesive force to aluminum is increased, and the adhesive force to the aluminum surface is improved. Therefore, the peel strength is increased; meanwhile, efficient copolymerization and crosslinking of acrylate are achieved through cation initiation, the cohesive strength is improved, and the adhesive strength of the adhesive is improved.

Description

Technical Field

[0001] This invention belongs to the field of power battery technology, specifically relating to an adhesive and its preparation method and application, and polyacrylic film and its application. Background Technology

[0002] With the rapid development of the global new energy vehicle industry, the market demand for power batteries, as a core component, has experienced explosive growth. During the production, storage, and transportation of power batteries, the blue film, as an important functional protective film, plays a crucial role in forming a physical barrier on the aluminum shell surface during these processes. This barrier prevents scratches or dents caused by friction and collisions, isolates the battery from external moisture, dust, and corrosive substances, and prevents insulation failure. As a vital protective medium for the aluminum shell surface, the adhesion performance between the blue film and the aluminum shell directly depends on the overall performance of the adhesive. Therefore, it is necessary to develop a high-temperature resistant, high-shear acrylic adhesive for the blue film to meet more stringent usage conditions. Summary of the Invention

[0003] The purpose of this invention is to provide an adhesive, its preparation method and application, and a polyacrylic film and its application.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an adhesive, the raw materials of which include polyacrylate and photoinitiator; The raw materials for preparing the polyacrylate include soft monomers, hard monomers, functional monomers, acrylate-based heptaepoxy POSS, and initiators. The acrylate-based heptaepoxy POSS has the following structure: Where R is ; R1 is , , , , , , Or -CH3; R2 is -H or -CH3; n=2~5, m+x+a=4000~7000.

[0005] Preferably, the acrylate-based hepta-epoxy POSS includes at least one of methacrylate hepta-epoxy POSS, heptyl methacrylate hepta-epoxy POSS, octyl methacrylate hepta-epoxy POSS, and lauryl methacrylate hepta-epoxy POSS. The soft monomer includes at least one of ethyl acrylate, butyl acrylate and isooctyl acrylate; The hard monomer includes at least one of acrylic acid, methyl acrylate and methyl methacrylate; The functional monomers include at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, cyclotrimethylolpropane methyl acetal acrylate, (ethoxy)bisphenol fluorene diacrylate and dipentaerythritol hexaacrylate. The initiator includes at least one of benzoyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile.

[0006] Preferably, the raw materials for preparing the polyacrylate, by mass parts, include 30-40 parts of soft monomer, 20-30 parts of hard monomer, 10-30 parts of functional monomer, 15-25 parts of acrylate-based heptaepoxy POSS and 0.5-1 parts of initiator.

[0007] Preferably, the photoinitiator includes at least one of cationic photoinitiator 250 and cationic photoinitiator 432; The mass ratio of the soft monomer to the photoinitiator is 30~40:0.5~4.

[0008] Preferably, the adhesive further includes pigments and / or reinforcing agents; The pigment includes at least one of blue inorganic pigment, green inorganic pigment, black inorganic pigment, white inorganic pigment, yellow inorganic pigment, red inorganic pigment, and orange inorganic pigment; The reinforcing agent includes at least one of fumed silica and white carbon black; The mass ratio of the soft monomer to the pigment is 30~40:0.5~1; The mass ratio of the soft monomer to the reinforcing agent is 30~40:3~5.

[0009] The present invention also provides a method for preparing the adhesive described in the above technical solution, comprising the following steps: The soft monomer, hard monomer, functional monomer and acrylate-based heptaepoxy POSS were mixed to obtain a monomer mixture; The initiator and solvent are mixed to obtain an initiator mixture; Half of the monomer mixture and one-third of the initiator mixture are mixed and subjected to preliminary polymerization to obtain a preliminary polymer; The remaining monomer mixture and half of the remaining initiator mixture are mixed, and the resulting mixture is added dropwise to the preliminary polymer to carry out the polymerization reaction and obtain the polymer. The polymer and the remaining initiator mixture are mixed and subjected to secondary polymerization to obtain the polyacrylate; The adhesive is obtained by mixing the polyacrylate and the photoinitiator.

[0010] Preferably, the initial polymerization temperature is 80~90℃ and the time is 0.5~1h; The polymerization reaction is carried out at a temperature of 80-90°C for 4-6 hours. The secondary polymerization is carried out at a temperature of 80-90℃ for 3-5 hours.

[0011] The present invention also provides a polyacrylic acid film, which is obtained by coating an adhesive; the adhesive is the adhesive described in the above technical solution or the adhesive prepared by the preparation method described in the above technical solution; The substrate used for coating includes release paper or polymer film.

[0012] The present invention also provides the application of the adhesive or the polyacrylic film described in the above technical solution in power batteries.

[0013] Preferably, the application includes: The adhesive is applied to the surface of the substrate to be adhered and then cured. Alternatively, the polyacrylic film can be applied to the surface of the substrate to be adhered to and then cured. The curing method is to use a UV lamp for curing, and the wavelength of the UV lamp is 365nm.

[0014] This invention provides an adhesive, the raw materials of which include polyacrylate and a photoinitiator; the raw materials for preparing the polyacrylate include soft monomers, hard monomers, functional monomers, acrylate-based heptaepoxy POSS, and an initiator; the acrylate-based heptaepoxy POSS has the following structure: Where R is ; R1 is , , , , , , Or -CH3; R2 is -H or -CH3; n=2~5, m+x+a=4000~7000.

[0015] Compared with the prior art, the beneficial effects of the present invention include: (1) In this invention, the acrylate obtained from soft monomers, hard monomers and functional monomers has the characteristic of low surface tension, which can improve the wettability of the resin system on the aluminum surface. The rapid polymerization initiated by cationic catalysts can lock this good wetting state, enhance its mechanical anchoring effect, thereby increasing the adhesion to aluminum and thus increasing the peel strength. At the same time, cationic initiation realizes efficient copolymerization and crosslinking of acrylate, improves cohesive strength, and improves the adhesion of the adhesive itself.

[0016] (2) By introducing long-chain acrylate-based hepta-epoxy POSS, it can form an interpenetrating network polymer with acrylate, which can alleviate the internal stress caused by curing shrinkage, improve the film-forming performance of polyacrylate, and make the resulting film more flexible.

[0017] (3) The polyacrylate prepared in this invention is a UV-curable adhesive film made of polyacrylate. After being bonded to the aluminum shell, it is cured by UV irradiation, which provides the required high shear force. Furthermore, due to the introduction of POSS groups and epoxy groups, the temperature resistance of the modified polyacrylate is improved. The modified polyacrylic acid is made into an adhesive film, which is convenient to operate and has strong conformability during the assembly of power batteries. After UV irradiation, its strength and hardness are higher than those of pure acrylic resin. Detailed Implementation

[0018] This invention provides an adhesive, the raw materials of which include polyacrylate and photoinitiator; The raw materials for preparing the polyacrylate include soft monomers, hard monomers, functional monomers, acrylate-based heptaepoxy POSS, and initiators. The acrylate-based heptaepoxy POSS has the following structure: Where R is ; R1 is , , , , , , Or -CH3; R2 is -H or -CH3; n=2~5, m+x+a=4000~7000.

[0019] The raw materials for preparing the polyacrylate provided by the present invention preferably include 30-40 parts of soft monomers by weight, specifically 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 parts. In the present invention, the soft monomers preferably include at least one of ethyl acrylate, butyl acrylate, and isooctyl acrylate.

[0020] Based on the mass fraction of the soft monomer, the raw materials for preparing the polyacrylate provided by the present invention preferably include 20-30 parts of hard monomer, specifically 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, and 30 parts. In the present invention, the hard monomer preferably includes at least one of acrylic acid, methyl acrylate, and methyl methacrylate.

[0021] Based on the mass fraction of the soft monomer, the raw materials for preparing the polyacrylate provided by the present invention preferably include 10 to 30 parts of functional monomer, specifically 10, 12, 15, 18, 20, 22, 25, 28, or 30 parts. In the present invention, the functional monomer preferably includes at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, cyclotrimethylolpropane methyl acetal acrylate, (ethoxy)bisphenol fluorene diacrylate, and dipentaerythritol hexaacrylate.

[0022] Based on the mass fraction of the soft monomer, the raw material for preparing the polyacrylate provided by the present invention preferably includes 15-25 parts of acrylate-based heptaepoxy POSS, specifically 15 parts, 18 parts, 20 parts, 22 parts, or 25 parts. In the present invention, n = 2-5, specifically 2, 3, 4, or 5; m + x + a = 4000-7000, specifically 4000, 5000, 6000, or 7000. In the present invention, the relative molecular weight of the acrylate-based heptaepoxy POSS is preferably 300,000-500,000. In the present invention, the acrylate-based heptaepoxy POSS preferably includes at least one of methacrylate heptaepoxy POSS, heptyl methacrylate heptaepoxy POSS, octyl methacrylate heptaepoxy POSS, and lauryl methacrylate heptaepoxy POSS.

[0023] Based on the mass fraction of the soft monomer, the raw materials for preparing the polyacrylate provided by the present invention preferably include 0.5 to 1 part initiator, specifically 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 parts. In the present invention, the initiator preferably includes at least one selected from benzoyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile.

[0024] In this invention, the photoinitiator preferably includes at least one of cationic photoinitiator 250 and cationic photoinitiator 432; the mass ratio of the soft monomer to the photoinitiator is preferably 30~40:0.5~4, specifically 30:0.5, 30:1, 30:2, 30:3, 30:4, 40:0.5, 40:1, 40:2, or 40:3.

[0025] In this invention, the adhesive preferably includes pigments and / or reinforcing agents; the pigments preferably include at least one selected from blue inorganic pigment, green inorganic pigment, black inorganic pigment, white inorganic pigment, yellow inorganic pigment, red inorganic pigment, and orange inorganic pigment; the reinforcing agents preferably include at least one selected from fumed silica and silica; the mass ratio of the soft monomer to the pigment is preferably 30~40:0.5~1; the mass ratio of the soft monomer to the reinforcing agent is preferably 30~40:3~5.

[0026] The present invention also provides a method for preparing the adhesive described in the above technical solution, comprising the following steps: The soft monomer, hard monomer, functional monomer and acrylate-based heptaepoxy POSS were mixed to obtain a monomer mixture; The initiator and solvent are mixed to obtain an initiator mixture; Half of the monomer mixture and one-third of the initiator mixture are mixed and subjected to preliminary polymerization to obtain a preliminary polymer; The remaining monomer mixture and half of the remaining initiator mixture are mixed, and the resulting mixture is added dropwise to the preliminary polymer to carry out the polymerization reaction and obtain the polymer. The polymer and the remaining initiator mixture are mixed and subjected to secondary polymerization to obtain the polyacrylate; The adhesive is obtained by mixing the polyacrylate and the photoinitiator.

[0027] In this invention, the solvent preferably includes at least one selected from ethyl acetate, butyl acetate, toluene, xylene, butanone, and acetone. In this invention, the mass ratio of the soft monomer to the solvent is preferably 30-40:100-200.

[0028] In this invention, the preferred temperature for the initial polymerization is 80-90°C, specifically 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, or 90°C; the preferred time is 0.5-1 h, specifically 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, or 1.0 h; the initial polymerization is preferably carried out under stirring conditions.

[0029] In this invention, the dripping time is preferably 2 to 3 hours.

[0030] In this invention, the preferred temperature for the polymerization reaction is 80-90°C, specifically 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, or 90°C; the preferred time is 4-6 hours, specifically 4 hours, 5 hours, or 6 hours (referring to the reaction time after the addition is completed); the polymerization reaction is preferably carried out under stirring conditions.

[0031] In this invention, the mixing of the polymer and the remaining initiator mixture is preferably carried out by adding the remaining initiator mixture dropwise to the polymer; the dropwise addition time is preferably 1-2 hours; the secondary polymerization temperature is preferably 80-90°C, specifically 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, or 90°C; the time is preferably 3-5 hours (referring to the reaction time after the dropwise addition is completed), specifically 3 hours, 4 hours, or 5 hours; the secondary polymerization is preferably carried out under stirring conditions. In this invention, after the secondary polymerization, it is also preferable to cool the system to no higher than 50°C and discharge the material. In this invention, secondary polymerization can eliminate residual monomers in the system.

[0032] In this invention, the mixing of the polyacrylate and the photoinitiator is preferably carried out under light-protected conditions. In this invention, when the adhesive further includes pigments and / or reinforcing agents, these are preferably added during the mixing stage of the polyacrylate and the photoinitiator.

[0033] The present invention also provides a polyacrylic film, which is obtained by coating an adhesive; the adhesive is the adhesive described in the above technical solution or the adhesive prepared by the preparation method described in the above technical solution; the substrate used for coating includes release paper or polymer film.

[0034] The present invention does not impose any particular limitation on the coating process; any process well known to those skilled in the art can be used. In the present invention, drying is preferably performed after coating.

[0035] The present invention also provides the application of the adhesive or the polyacrylic film described in the above technical solution in power batteries.

[0036] In this invention, the application preferably includes: The adhesive is applied to the surface of the substrate to be adhered and then cured. Alternatively, the polyacrylic film can be applied to the surface of the substrate to be adhered to and then cured. In this invention, the curing method is preferably curing by UV lamp irradiation, and the wavelength of the UV lamp is preferably 365nm.

[0037] In this invention, when the adhesive contains blue inorganic pigment, the resulting adhesive film is preferably used as a blue film for power battery encapsulation.

[0038] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0039] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1 Soft monomers: 15 parts butyl acrylate, 15 parts isooctyl acrylate; Hard monomer: 20 parts methyl acrylate, 8 parts acrylic acid; Functional monomers: 10 parts 2-hydroxyethyl acrylate, 5 parts glycidyl methacrylate, 5 parts cyclotrimethylolpropane methyl acetal acrylate; Acrylate-based hepta-epoxy POSS: 10 parts methacrylate hepta-epoxy POSS, 5 parts lauryl methacrylate hepta-epoxy POSS; Initiator: 0.5 parts azobisisobutyronitrile; Solvent: 50 parts ethyl acetate, 20 parts butyl acetate, 69.5 parts toluene; Photoinitiator: 1 part cationic photoinitiator 250, 1 part cationic photoinitiator 432; Pigment: 0.5 parts blue inorganic pigment; Reinforcing agent: 3 parts fumed silica; Preparation method: The soft monomer, hard monomer, functional monomer and acrylate-based heptaepoxy POSS were mixed to obtain a monomer mixture; the initiator and solvent were mixed to obtain an initiator mixture. Half of the monomer mixture and one-third of the initiator mixture were mixed, stirred evenly, and heated to 82°C. The initial polymerization reaction was carried out for 0.5 hours to obtain the initial polymer. The remaining monomer mixture and half of the remaining initiator mixture were mixed. Under stirring, the resulting mixture was added dropwise to the preliminary polymer. The dropping rate was controlled to be completed in 2 hours. After the dropping was completed, the polymerization reaction was carried out at 82°C for 4 hours to obtain the polymer. Under stirring conditions, the remaining initiator mixture was added dropwise to the polymer, and the dropping rate was controlled to be completed in 1.5 hours. Secondary polymerization was carried out at 82°C for 3 hours. After the reaction was completed, the temperature was lowered by 50°C and the product was discharged to obtain polyacrylate. The adhesive is obtained by stirring and mixing polyacrylate, photoinitiator, pigment and reinforcing agent under light-protected conditions.

[0041] Example 2 Soft monomer: 20 parts isooctyl acrylate, 10 parts ethyl acrylate; Hard monomer: 15 parts methyl methacrylate, 10 parts acrylic acid; Functional monomers: 10 parts 2-hydroxyethyl acrylate, 10 parts glycidyl methacrylate; Acrylate-based hepta-epoxy POSS: 10 parts lauryl methacrylate hepta-epoxy POSS, 15 parts methacrylate hepta-epoxy POSS; Initiator: 0.8 parts azobisisoheptanenitrile; Solvent: 70 parts ethyl acetate, 30 parts toluene, 42.5 parts xylene; Photoinitiator: 1 part cationic photoinitiator 250, 1 part cationic photoinitiator 432; Pigment: 0.5 parts blue inorganic pigment; Reinforcing agent: 3 parts fumed silica; Preparation method: The soft monomer, hard monomer, functional monomer and acrylate-based heptaepoxy POSS were mixed to obtain a monomer mixture; the initiator and solvent were mixed to obtain an initiator mixture. Half of the monomer mixture and one-third of the initiator mixture were mixed, stirred evenly, and heated to 86°C. The initial polymerization reaction was carried out for 1 hour to obtain the initial polymer. The remaining monomer mixture and half of the remaining initiator mixture were mixed. Under stirring, the resulting mixture was added dropwise to the preliminary polymer. The dropping rate was controlled to be completed within 2 hours. After the dropping was completed, the polymerization reaction was carried out at 86°C for 5 hours to obtain the polymer. Under stirring conditions, the remaining initiator mixture was added dropwise to the polymer, and the dropping rate was controlled to be completed in 2 hours. Secondary polymerization was carried out at 86°C for 4 hours. After the reaction was completed, the temperature was lowered by 50°C and the product was discharged to obtain polyacrylate. The adhesive is obtained by stirring and mixing polyacrylate, photoinitiator, pigment and reinforcing agent under light-protected conditions.

[0042] Example 3 Soft monomer: 30 parts butyl acrylate, 10 parts methyl methacrylate; Hard monomer: 10 parts acrylic acid, 5 parts methyl acrylate; Functional monomers: 10 parts 2-hydroxyethyl methacrylate, 5 parts 2-hydroxypropyl acrylate, 5 parts glycidyl methacrylate; Acrylate-based hepta-epoxy POSS: 10 parts hepta-epoxy methacrylate POSS, 10 parts hepta-epoxy methacrylate POSS; Initiator: 1 part azobisisobutyronitrile; Solvents: 50 parts ethyl acetate, 50 parts toluene, 45.5 parts xylene; Photoinitiator: 1 part cationic photoinitiator 250, 1 part cationic photoinitiator 432; Pigment: 0.5 parts blue inorganic pigment; Reinforcing agent: 3 parts fumed silica; Preparation method: The soft monomer, hard monomer, functional monomer and acrylate-based heptaepoxy POSS were mixed to obtain a monomer mixture; the initiator and solvent were mixed to obtain an initiator mixture. Half of the monomer mixture and one-third of the initiator mixture were mixed, stirred evenly, and heated to 88°C. The initial polymerization reaction was carried out for 0.5 hours to obtain the initial polymer. The remaining monomer mixture and half of the remaining initiator mixture were mixed. Under stirring, the resulting mixture was added dropwise to the preliminary polymer. The dropping rate was controlled to be completed within 3 hours. After the dropping was completed, the polymerization reaction was carried out at 88°C for 5 hours to obtain the polymer. Under stirring conditions, the remaining initiator mixture was added dropwise to the polymer, and the dropping rate was controlled to be completed in 2 hours. Secondary polymerization was carried out at 88°C for 3 hours. After the reaction was completed, the temperature was lowered by 50°C and the product was discharged to obtain polyacrylate. The adhesive is obtained by stirring and mixing polyacrylate, photoinitiator, pigment and reinforcing agent under light-protected conditions.

[0043] Example 4 Soft monomer: 35 parts butyl acrylate, 5 parts isooctyl acrylate; Hard monomer: 10 parts acrylic acid, 20 parts methyl methacrylate; Functional monomers: 5 parts 2-hydroxyethyl acrylate, 10 parts glycidyl methacrylate, 5 parts cyclotrimethylolpropane methyl acetal acrylate; Acrylate-based hepta-epoxy POSS: 15 parts methacrylate hepta-epoxy POSS, 10 parts lauryl methacrylate hepta-epoxy POSS; Initiator: 0.8 parts azobisisoheptanenitrile; Solvents: 30 parts ethyl acetate, 50 parts toluene, 50 parts xylene, 42.5 parts butyl acetate; Photoinitiator: 1 part cationic photoinitiator 250, 1 part cationic photoinitiator 432; Pigment: 0.5 parts blue inorganic pigment; Reinforcing agent: 5 parts fumed silica; Preparation method: The soft monomer, hard monomer, functional monomer and acrylate-based heptaepoxy POSS were mixed to obtain a monomer mixture; the initiator and solvent were mixed to obtain an initiator mixture. Half of the monomer mixture and one-third of the initiator mixture were mixed, stirred evenly, and heated to 88°C. The initial polymerization reaction was carried out for 0.5 hours to obtain the initial polymer. The remaining monomer mixture and half of the remaining initiator mixture were mixed. Under stirring, the resulting mixture was added dropwise to the preliminary polymer. The dropping rate was controlled to be completed in 2.5 hours. After the dropping was completed, the polymerization reaction was carried out at 88°C for 5 hours to obtain the polymer. Under stirring conditions, the remaining initiator mixture was added dropwise to the polymer, and the dropping rate was controlled to be completed in 2 hours. Secondary polymerization was carried out at 88°C for 4 hours. After the reaction was completed, the temperature was lowered by 50°C and the product was discharged to obtain polyacrylate. The adhesive is obtained by stirring and mixing polyacrylate, photoinitiator, pigment and reinforcing agent under light-protected conditions.

[0044] Example 5 Soft monomer: 35 parts ethyl acrylate, 5 parts isooctyl acrylate; Hard monomer: 10 parts acrylic acid, 20 parts methyl methacrylate; Functional monomers: 5 parts 2-hydroxyethyl acrylate, 10 parts glycidyl methacrylate, 5 parts cyclotrimethylolpropane methyl acetal acrylate; Acrylate-based hepta-epoxy POSS: 15 parts methacrylate hepta-epoxy POSS, 10 parts lauryl methacrylate hepta-epoxy POSS; Initiator: 0.8 parts azobisisoheptanenitrile; Solvents: 30 parts ethyl acetate, 50 parts toluene, 50 parts xylene, 42.5 parts butyl acetate; Photoinitiator: 1 part cationic photoinitiator 250, 1 part cationic photoinitiator 432; Pigment: 0.5 parts blue inorganic pigment; Reinforcing agent: 5 parts fumed silica; Preparation method: The soft monomer, hard monomer, functional monomer and acrylate-based heptaepoxy POSS were mixed to obtain a monomer mixture; the initiator and solvent were mixed to obtain an initiator mixture. Half of the monomer mixture and one-third of the initiator mixture were mixed, stirred evenly, and heated to 88°C. The initial polymerization reaction was carried out for 0.5 hours to obtain the initial polymer. The remaining monomer mixture and half of the remaining initiator mixture were mixed. Under stirring, the resulting mixture was added dropwise to the preliminary polymer. The dropping rate was controlled to be completed in 2.5 hours. After the dropping was completed, the polymerization reaction was carried out at 88°C for 5 hours to obtain the polymer. Under stirring conditions, the remaining initiator mixture was added dropwise to the polymer, and the dropping rate was controlled to be completed in 2 hours. Secondary polymerization was carried out at 88°C for 4 hours. After the reaction was completed, the temperature was lowered by 50°C and the product was discharged to obtain polyacrylate. The adhesive is obtained by stirring and mixing polyacrylate, photoinitiator, pigment and reinforcing agent under light-protected conditions.

[0045] Example 6 Soft monomer: 35 parts ethyl acrylate, 5 parts butyl acrylate; Hard monomer: 10 parts acrylic acid, 20 parts methyl methacrylate; Functional monomers: 5 parts 2-hydroxyethyl acrylate, 10 parts glycidyl methacrylate, 5 parts cyclotrimethylolpropane methyl acetal acrylate, 5 parts 30-ethoxybisphenol A diacrylate, 5 parts dipentaerythritol hexaacrylate. Acrylate-based hepta-epoxy POSS: 15 parts methacrylate hepta-epoxy POSS, 10 parts lauryl methacrylate hepta-epoxy POSS; Initiator: 0.8 parts azobisisoheptanenitrile; Solvents: 30 parts ethyl acetate, 50 parts toluene, 50 parts xylene, 57.5 parts butanone; Photoinitiator: 1 part cationic photoinitiator 250, 1 part cationic photoinitiator 432; Pigment: 0.5 parts blue inorganic pigment; Reinforcing agent: 3 parts fumed silica; Preparation method: The soft monomer, hard monomer, functional monomer and acrylate-based heptaepoxy POSS were mixed to obtain a monomer mixture; the initiator and solvent were mixed to obtain an initiator mixture. Half of the monomer mixture and one-third of the initiator mixture were mixed, stirred evenly, and heated to 88°C. The initial polymerization reaction was carried out for 0.5 hours to obtain the initial polymer. The remaining monomer mixture and half of the remaining initiator mixture were mixed. Under stirring, the resulting mixture was added dropwise to the preliminary polymer. The dropping rate was controlled to be completed in 2.5 hours. After the dropping was completed, the polymerization reaction was carried out at 88°C for 5 hours to obtain the polymer. Under stirring conditions, the remaining initiator mixture was added dropwise to the polymer, and the dropping rate was controlled to be completed in 2 hours. Secondary polymerization was carried out at 88°C for 4 hours. After the reaction was completed, the temperature was lowered by 50°C and the product was discharged to obtain polyacrylate. The adhesive is obtained by stirring and mixing polyacrylate, photoinitiator, pigment and reinforcing agent under light-protected conditions.

[0046] Performance testing Test Example 1 Viscosity test The viscosity of the polyacrylates obtained in Examples 1 to 6 was tested according to GB / T 20794-2013, and the results are shown in Table 1. Table 1. Viscosities of polyacrylates obtained in Examples 1-6

[0047] 2. Solid content test The solid content of the polyacrylates obtained in Examples 1 to 6 was tested according to GB / T 2793-1995, and the results are shown in Table 2. Table 2 shows the solid content of the polyacrylates obtained in Examples 1-6.

[0048] Test Example 2 The adhesives obtained in Examples 1-6 were coated onto release paper and baked at 120°C for 2 minutes to obtain a modified polyacrylate film with a thickness of 100±10 μm. The performance of the obtained modified polyacrylate film was then tested. 1. Tensile shear strength test Test sample preparation: (1) Cut the modified polyacrylate film into 13mm wide samples, attach them to the underside of the shearing plate (3003 aluminum), remove the release paper, and irradiate them with a 1500mW LED UV lamp with a UV wavelength of 365nm; (2) attach the other side of the shearing plate and use dovetail clips to fix the two shearing plates; (3) let the shearing plates stand at room temperature for 7 days to allow the modified polyacrylate film to fully cure, remove the dovetail clips, and conduct the test.

[0049] The tensile shear strength of the film was tested according to GB / T 7124-2008, and the results are shown in Table 3. Table 3 Tensile shear strength of the films obtained in Examples 1-6

[0050] 2. Shore D hardness test Test sample preparation: After removing the release paper, the modified polyacrylate film was stacked in 40 layers and then irradiated with a 1500mW LED UV lamp with a UV wavelength of 365nm. After standing at room temperature for 7 days, the modified polyacrylate film was fully cured and tested.

[0051] The Shore D hardness of the film was tested according to GB 2411-2008, and the results are shown in Table 4. Table 4 Shore D hardness of the films obtained in Examples 1-6

[0052] 3. Tensile strength / elongation at break test Test sample preparation: (1) The modified polyacrylate film was irradiated with a 1500mW LED UV lamp with a UV wavelength of 365nm; it was left to stand at room temperature for 7 days to fully cure the modified polyacrylate film; (2) The fully cured modified polyacrylate film was cut into strips with a width of 15mm and a length of 150mm, and two parallel lines with a spacing of 50mm were marked in the middle of the strips.

[0053] The tensile strength / elongation at break of the films in Examples 1 to 6 were tested according to GB / T 1040.3-2006, and the results are shown in Table 5. Table 5 Tensile strength / elongation at break of the adhesive films obtained in Examples 1-6

[0054] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An adhesive, characterized in that, The raw materials for preparation include polyacrylate and photoinitiator; The raw materials for preparing the polyacrylate include soft monomers, hard monomers, functional monomers, acrylate-based heptaepoxy POSS, and initiators. The acrylate-based heptaepoxy POSS has the following structure: ； Where R is ; R1 is , , , , , , Or -CH3; R2 is -H or -CH3; n=2~5, m+x+a=4000~7000.

2. The adhesive according to claim 1, characterized in that, The acrylate-based heptacyclooxygen POSS includes at least one of methacrylate heptacyclooxygen POSS, heptyl methacrylate heptacyclooxygen POSS, octyl methacrylate heptacyclooxygen POSS, and lauryl methacrylate heptacyclooxygen POSS. The soft monomer includes at least one of ethyl acrylate, butyl acrylate and isooctyl acrylate; The hard monomer includes at least one of acrylic acid, methyl acrylate and methyl methacrylate; The functional monomers include at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, cyclotrimethylolpropane methyl acetal acrylate, (ethoxy)bisphenol fluorene diacrylate and dipentaerythritol hexaacrylate. The initiator includes at least one of benzoyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile.

3. The adhesive according to claim 1 or 2, characterized in that, The raw materials for preparing the polyacrylate, by mass parts, include 30-40 parts of soft monomer, 20-30 parts of hard monomer, 10-30 parts of functional monomer, 15-25 parts of acrylate-based heptaepoxy POSS and 0.5-1 parts of initiator.

4. The adhesive according to claim 1, characterized in that, The photoinitiator includes at least one of cationic photoinitiator 250 and cationic photoinitiator 432; The mass ratio of the soft monomer to the photoinitiator is 30~40:0.5~4.

5. The adhesive according to claim 1, characterized in that, The adhesive also includes pigments and / or reinforcing agents; The pigment includes at least one of blue inorganic pigment, green inorganic pigment, black inorganic pigment, white inorganic pigment, yellow inorganic pigment, red inorganic pigment, and orange inorganic pigment; The reinforcing agent includes at least one of fumed silica and white carbon black; The mass ratio of the soft monomer to the pigment is 30~40:0.5~1; The mass ratio of the soft monomer to the reinforcing agent is 30~40:3~5.

6. A method for preparing the adhesive according to any one of claims 1 to 5, characterized in that, Includes the following steps: The soft monomer, hard monomer, functional monomer and acrylate-based heptaepoxy POSS were mixed to obtain a monomer mixture; The initiator and solvent are mixed to obtain an initiator mixture; Half of the monomer mixture and one-third of the initiator mixture are mixed and subjected to preliminary polymerization to obtain a preliminary polymer; The remaining monomer mixture and half of the remaining initiator mixture are mixed, and the resulting mixture is added dropwise to the preliminary polymer to carry out the polymerization reaction and obtain the polymer. The polymer and the remaining initiator mixture are mixed and subjected to secondary polymerization to obtain the polyacrylate; The adhesive is obtained by mixing the polyacrylate and the photoinitiator.

7. The preparation method according to claim 6, characterized in that, The initial polymerization temperature is 80~90℃, and the time is 0.5~1h; The polymerization reaction is carried out at a temperature of 80-90°C for 4-6 hours. The secondary polymerization is carried out at a temperature of 80-90℃ for 3-5 hours.

8. A polyacrylic acid film, characterized in that, Obtained by coating an adhesive; wherein the adhesive is the adhesive according to any one of claims 1 to 5 or the adhesive prepared by the preparation method according to claim 6 or 7; The substrate used for coating includes release paper or polymer film.

9. The application of the adhesive according to any one of claims 1 to 5 or the polyacrylic film according to claim 8 in a power battery.

10. The application according to claim 9, characterized in that, The applications include: The adhesive is applied to the surface of the substrate to be adhered and then cured. Alternatively, the polyacrylic film can be applied to the surface of the substrate to be adhered to and then cured. The curing method is to use a UV lamp for curing, and the wavelength of the UV lamp is 365nm.

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