Photoalkali-generating UV curing adhesive, insulating film and preparation method

Abstract

This invention discloses a photo-alkali-generating UV-curable adhesive, an insulating film, and a preparation method thereof. The adhesive comprises the following components by weight: 100 parts modified polyacrylate, 25-35 parts epoxy resin, 15-25 parts thiol, 4-8 parts photo-alkali-generating agent, 0.1-0.5 parts photosensitizer, 0.5-1.5 parts silane coupling agent, and 80-120 parts first organic solvent. The UV-curable adhesive of this invention generates an organic nitrogen base after being irradiated with UVA light at a certain energy. This base first initiates a Michael addition reaction between the thiol and the self-made polyacrylate; then, through a nucleophilic addition reaction, it initiates a ring-opening reaction between the epoxy group and the thiol. The two react synergistically to form an interpenetrating network (IPN) structure. The UV-curable adhesive of this invention has the advantages of high shear strength and good heat resistance, and the coating process is simple and easy to implement, showing good application prospects in the field of battery insulating films.

Description

Technical Field

[0001] This invention relates to the field of adhesive materials and membrane materials, and particularly to a photo-alkali-generating UV-curable adhesive, an insulating film, and a preparation method thereof. Background Technology

[0002] Typically, battery insulating film products are used in three scenarios: insulation of the end plates and side plates of battery modules, insulation of battery pack housings, and insulation of other components such as water-cooling plates. Currently, most laminated battery insulating films are composed of structural adhesives such as polyester, polyurethane, epoxy resin, and polyolefin, combined with a PI film. During application, they require hot-pressing, leading to low construction efficiency, high requirements for equipment and construction processes, safety hazards, and the inability to reposition them after application. In contrast, UV-curable adhesives offer advantages such as simple, fast, efficient, and environmentally friendly curing processes.

[0003] To meet industrial demands, a certain degree of delayed curing performance is required, providing sufficient processing time for subsequent processes while enabling rapid setting within a short period. However, traditional acrylate free radical photopolymerization systems used in UV-curable adhesives have relatively fast curing rates, failing to provide an operational window for bonding opaque substrates. In contrast, photo-alkali-generating UV curing systems produce alkaline active species after UV irradiation. This process is relatively slow, yet the curing reaction can proceed even in darkness, achieving the desired delayed curing. Furthermore, the polymerization process is free of oxygen inhibition and does not cause corrosion to metallic substrates, making its application prospects very broad.

[0004] Therefore, it is necessary to develop a photo-alkali-generating UV-curing adhesive for use in battery insulating films, such as water-cooled plate insulating films. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a photo-alkali-generating UV-curable adhesive, an insulating film, and a preparation method, addressing the shortcomings of the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: In the first aspect of the present invention, a photoalkali-generating UV-curable adhesive is provided, comprising the following raw material components by weight: 100 parts of modified polyacrylate, 25-35 parts of epoxy resin, 15-25 parts of thiol, 4-8 parts of photoalkali-generating agent, 0.1-0.5 parts of photosensitizer, 0.5-1.5 parts of silane coupling agent, and 80-120 parts of first organic solvent.

[0007] Preferably, the raw materials for preparing modified polyacrylate include, by weight: 20-40 parts of soft monomer, 20-40 parts of hard monomer, 5-10 parts of epoxy-containing vinyl monomer, 5-15 parts of heterocyclic functional monomer, 2.5-5 parts of crosslinking monomer, 0.2-0.6 parts of initiator, and 150-250 parts of second organic solvent.

[0008] Preferably, the modified polyacrylate has a solid content of 25%-35%, a weight-average molecular weight of 80w-120w, a glass transition temperature of -10℃ to 0℃, and its molecular structure contains both carbon-carbon double bonds and epoxy groups.

[0009] Preferably, the soft monomer is selected from one or more of n-octyl acrylate, isooctyl methacrylate, n-butyl acrylate, lauryl acrylate, and octadecyl acrylate;

[0010] The hard monomer is selected from one or more of methyl acrylate, methyl methacrylate, and ethyl methacrylate;

[0011] The epoxy-containing vinyl monomer is selected from one or more of glycidyl methacrylate, 3,4-epoxycyclohexyl methacrylate and 3,4-epoxycyclohexyl methacrylate.

[0012] The heterocyclic functional monomer is selected from one or more of dicyclopentadiene acrylate, acryloylmorpholine, isobornyl acrylate, and tetrahydrofuran acrylate;

[0013] The crosslinking monomer is selected from one of acrylic acid, methacrylic acid, and β-acryloyloxypropionic acid.

[0014] The initiator is selected from at least one of acyl peroxide initiators and azo compound initiators;

[0015] The second organic solvent is selected from one or more of ethyl acetate, butyl acetate, and toluene.

[0016] Preferably, the modified polyacrylate is prepared by the following method:

[0017] S1. Under an inert gas atmosphere, the soft monomer, hard monomer, epoxy-containing vinyl monomer, part of heterocyclic functional monomer and part of second organic solvent are stirred evenly. The initiator in the first part is added first, and the reaction is carried out at 66.5℃-67.5℃ for 1h-2h to obtain the first reaction solution.

[0018] S2. Add the remaining heterocyclic functional monomer and the initiator of the second part to the first reaction solution, stir the reaction at 69℃-71℃, control the dropping time to 1.5h-2h, and continue the reaction for 0.5-1h after the dropping is completed to obtain the second reaction solution.

[0019] S3. Add the remaining initiator from the third part to the second reaction solution, and stir the reaction at 75℃-78℃ for 3h-6h to obtain the third reaction solution.

[0020] S4. Add the crosslinking monomer, catalyst, and the remaining portion of the second organic solvent to the third reaction solution in sequence, and stir the reaction at 85℃-90℃ for 3-5 hours to obtain the modified polyacrylate.

[0021] Preferably, the epoxy resin is composed of bisphenol A epoxy resin and alicyclic epoxy resin in a mass ratio of 1-3:1, wherein the epoxy equivalent of the bisphenol A epoxy resin is 180-240 g / mol and the epoxy equivalent of the alicyclic epoxy resin is 125-145 g / mol.

[0022] Preferably, the photoalkali-generating agent is selected from one of WPBG300, WPBG345, TJ-PBG-801, and O0396.

[0023] Preferably, the thiol is selected from one of trifunctional or tetrafunctional thiols;

[0024] The photosensitizer is selected from one of ITX, DETX, amine sensitizer EPD, amine sensitizer OPD, TR-PSS-402, and TR-PSS-303;

[0025] The silane coupling agent is selected from one of the epoxy-containing silane coupling agents;

[0026] The first organic solvent is selected from one or more of ethyl acetate, butyl acetate, and toluene.

[0027] In a second aspect, the present invention provides a method for preparing the photoalkali-generating UV-curable adhesive as described above, comprising the following steps: mixing 100 parts of modified polyacrylate, 25-35 parts of epoxy resin, 15-25 parts of thiol, 4-8 parts of photoalkali-generating agent, 0.1-0.5 parts of sensitizer, 0.5-1.5 parts of silane coupling agent and 80-120 parts of first organic solvent according to the mass ratio, and stirring evenly to obtain the photoalkali-generating UV-curable adhesive.

[0028] In a third aspect, the present invention provides an insulating film prepared by means of the following method: uniformly coating an insulating base film with a photo-alkali-generating UV-curable adhesive as described above, baking it at 80-120°C for 3-8 minutes, and then bonding a release film to the adhesive surface to obtain the insulating film;

[0029] When using this insulating film, first expose it to UVA light, then peel off the release film and attach the adhesive side of the insulating film to the object at room temperature, and let it stand until it is fully cured.

[0030] The beneficial effects of this invention are:

[0031] This invention provides a photoalkali-generating UV-curable adhesive, an insulating film, and a preparation method thereof. The photoalkali-generating UV-curable adhesive provided by this invention, after being irradiated by UVA light (wavelength 365nm), produces an organic base that catalyzes a relatively slow curing reaction between thiols and epoxy groups, providing a workable time of 10-30 minutes. After bonding, it only needs to be left to stand at room temperature to achieve complete curing. It has the advantages of delayed curing, simple coating process, high efficiency, and safety.

[0032] The insulating film provided by this invention employs anionic photocuring. The organic nitrogen alkali generated by the photo-alkali-producing agent is stable in air, the curing process is unaffected by oxygen, and it is not easily corroded when applied to metal coatings, with very mild operating conditions. After photocuring, the adhesive of this invention first initiates Michael addition between the remaining carbon-carbon double bonds of the modified polyacrylate and thiols, and then initiates a ring-opening reaction between the thiols and epoxy groups. The two curing methods work synergistically to form an interpenetrating network (IPN) structure, which reduces volume shrinkage while maintaining certain film-forming properties.

[0033] In some preferred embodiments, the insulating film of the present invention can achieve the following indicators: at 200°C for 1 hour, the thermal shrinkage rate of the insulating film is <0.20%; after the insulating film is applied to an aluminum plate and fully cured, the shear strength at 23°C is >10MPa and the peel strength is >45N / inch; the insulating film of the present invention has the advantages of high shear strength and good high temperature resistance, and has good application prospects in the field of battery insulating film. Attached Figure Description

[0034] Figure 1 The infrared spectrum is that of the modified polyacrylate prepared in Example 1 of the present invention. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0036] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available. For examples where specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer are followed. For reagents or instruments whose manufacturers are not specified, they are all commercially available products.

[0038] This invention provides a photoalkali-generating UV-curable adhesive, comprising the following raw material components by weight: 100 parts modified polyacrylate, 25-35 parts epoxy resin, 15-25 parts thiol, 4-8 parts photoalkali-generating agent, 0.1-0.5 parts photosensitizer, 0.5-1.5 parts silane coupling agent, and 80-120 parts first organic solvent.

[0039] In a preferred embodiment, the raw materials for preparing the modified polyacrylate include, by weight, 20-40 parts of soft monomer, 20-40 parts of hard monomer, 5-10 parts of epoxy-containing vinyl monomer, 5-15 parts of heterocyclic functional monomer, 2.5-5 parts of crosslinking monomer, 0.2-0.6 parts of initiator, and 150-250 parts of second organic solvent.

[0040] In a preferred embodiment, the modified polyacrylate has a solid content of 25%-35%, a weight-average molecular weight of 80w-120w, a glass transition temperature of -10℃ to 0℃, and its molecular structure contains both carbon-carbon double bonds and epoxy groups.

[0041] In a preferred embodiment, the soft monomer is selected from one or more of n-octyl acrylate, isooctyl methacrylate, n-butyl acrylate, lauryl acrylate, and octadecyl acrylate.

[0042] In a preferred embodiment, the hard monomer is selected from one or more of methyl acrylate, methyl methacrylate, and ethyl methacrylate.

[0043] In a preferred embodiment, the epoxy-containing vinyl monomer is selected from one or more of glycidyl methacrylate, 3,4-epoxycyclohexyl methacrylate and 3,4-epoxycyclohexyl methacrylate.

[0044] In a preferred embodiment, the heterocyclic functional monomer is selected from one or more of dicyclopentadiene acrylate, acryloylmorpholine, isobornyl acrylate, and tetrahydrofuran acrylate.

[0045] In a preferred embodiment, the crosslinking monomer is selected from acrylic acid, methacrylic acid, and β-acryloyloxypropionic acid.

[0046] In a preferred embodiment, the initiator is selected from at least one of acyl peroxide initiators and azo compound initiators.

[0047] In a preferred embodiment, the second organic solvent is selected from one or more of ethyl acetate, butyl acetate, and toluene.

[0048] In a preferred embodiment, the modified polyacrylate is prepared by the following method:

[0049] S1. Under an inert gas atmosphere, the soft monomer, hard monomer, epoxy-containing vinyl monomer, part of heterocyclic functional monomer and part of second organic solvent are stirred evenly. The initiator in the first part is added first, and the reaction is carried out at 66.5℃-67.5℃ for 1h-2h to obtain the first reaction solution.

[0050] S2. Add the remaining heterocyclic functional monomer and the initiator of the second part to the first reaction solution, stir the reaction at 69℃-71℃, control the dropping time to 1.5h-2h, and continue the reaction for 0.5-1h after the dropping is completed to obtain the second reaction solution.

[0051] S3. Add the remaining initiator from the third part to the second reaction solution, and stir the reaction at 75℃-78℃ for 3h-6h to obtain the third reaction solution.

[0052] S4. Add the crosslinking monomer, catalyst, and the remaining portion of the second organic solvent to the third reaction solution in sequence, and stir the reaction at 85℃-90℃ for 3-5 hours to obtain the modified polyacrylate.

[0053] In a preferred embodiment, the epoxy resin is composed of bisphenol A epoxy resin and alicyclic epoxy resin in a mass ratio of 1-3:1, wherein the epoxy equivalent of the bisphenol A epoxy resin is 180-240 g / mol, and the epoxy equivalent of the alicyclic epoxy resin is 125-145 g / mol.

[0054] In a preferred embodiment, the photo-alkali-generating agent is selected from one of WPBG300, WPBG345, TJ-PBG-801, and O0396.

[0055] In a preferred embodiment, the thiol is selected from either a trifunctional thiol or a tetrafunctional thiol.

[0056] In a preferred embodiment, the photosensitizer is selected from one of ITX, DETX, amine sensitizer EPD, amine sensitizer OPD, TR-PSS-402, and TR-PSS-303.

[0057] In a preferred embodiment, the silane coupling agent is selected from one of epoxy-containing silane coupling agents.

[0058] In a preferred embodiment, the first organic solvent is selected from one or more of ethyl acetate, butyl acetate, and toluene.

[0059] The present invention also provides a method for preparing the photoalkali-generating UV-curable adhesive as described above, comprising the following steps: mixing 100 parts of modified polyacrylate, 25-35 parts of epoxy resin, 15-25 parts of thiol, 4-8 parts of photoalkali-generating agent, 0.1-0.5 parts of sensitizer, 0.5-1.5 parts of silane coupling agent and 80-120 parts of first organic solvent according to the mass ratio, and stirring evenly to obtain the photoalkali-generating UV-curable adhesive.

[0060] The present invention also provides an insulating film, which is prepared by the following method: uniformly coating the insulating base film with the photo-alkali-generating UV curing adhesive as described above, baking at 80-120°C for 3-8 minutes, and then bonding a release film to the adhesive surface to obtain the insulating film;

[0061] When using this insulating film, first expose it to UVA light, then peel off the release film and attach the adhesive side of the insulating film to the object at room temperature, and let it stand until it is fully cured.

[0062] The photoalkali-generating UV-curable adhesive of this invention, upon irradiation with UVA light (wavelength 365nm), causes the photoalkali-generating agent and photosensitizer to gradually decompose and produce an organic nitrogen base. At room temperature, the modified polyacrylate rapidly undergoes a Michael addition reaction with the thiol, forming a preliminary curing state, which can be directly applied to the surface of the substrate at room temperature. The organic base then further initiates a nucleophilic addition reaction between the thiol and the epoxy groups and epoxy resin on the modified polyacrylate. This reaction is relatively slow at room temperature, delaying curing and providing a workable time of 10-30 minutes. After bonding, complete curing can be achieved simply by allowing it to stand at room temperature. Taking the photoalkali-generating agent O0396 as an example, its reaction mechanism is as follows:

[0063]

[0064] In this context, R, R1, and R2 all refer to alkyl groups with different numbers of carbon atoms.

[0065] The above is the general concept of the present invention. Based on this, detailed embodiments and comparative examples are provided below to further illustrate the present invention.

[0066] The sources of the main raw materials involved in the following examples and comparative examples are as follows:

[0067] Isooctyl methacrylate, lauryl acrylate, methyl acrylate, dicyclopentadiene acrylate, and acrylic acid were purchased from Shanghai Hechuang Chemical Co., Ltd.

[0068] Glycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, 3,4-epoxycyclohexyl methacrylate, 3,4-epoxycyclohexylformic acid-3',4'-epoxycyclohexylmethyl ester (TTA21) were purchased from Jiangsu Tetra New Material Technology Co., Ltd.

[0069] Azobisisobutyronitrile, tetrabutylammonium bromide, and KH560 were purchased from Sinopharm Reagent and were of analytical grade.

[0070] Bisphenol A epoxy resins E-51 and E-44 were purchased from Baichen Insulation Materials Co., Ltd.

[0071] Isopropylthioxanthone (ITX) was purchased from Double Bond Chemical Co., Ltd.

[0072] The photo-alkali-producing agent WPBG300 was purchased from Shanghai Jinpan Biotechnology Co., Ltd.

[0073] Trimethylolpropane tris(3-mercaptopropionic acid) ester (TMMP), pentaerythritol tetrakis(3-mercaptopropionic acid) ester (PETMP), and dipentaerythritol hexa(3-mercaptopropionic acid) ester (DPMP) were purchased from TCI.

[0074] Ethyl acetate and toluene were purchased from Shandong Xinge Chemical Co., Ltd., and were of industrial purity.

[0075] The main parameters of the modified polyacrylates prepared in the following examples and comparative examples are as follows: solid content of 25%-35%, weight-average molecular weight of 90w-110w, and glass transition temperature of -8℃ to -2℃.

[0076] Example 1

[0077] A photoalkali-generating UV-curable adhesive is prepared by the following steps: Under light-protected conditions, 100 parts by weight of modified polyacrylate, 20 parts by weight of epoxy resin (E-51 epoxy resin, 10 parts by weight of TTA21), 20 parts by weight of thiol (PETMP), 6 parts by weight of photoalkali-generating agent (WPBG300), 0.3 parts by weight of photosensitizer (ITX), 1 part by weight of silane coupling agent (KH560), and 100 parts by weight of first organic solvent are added sequentially and stirred until uniformly mixed to obtain the adhesive.

[0078] In this embodiment, the raw materials for preparing the modified polyacrylate include, by weight:

[0079] Soft monomers: 20 parts isooctyl methacrylate, 10 parts lauryl acrylate; Hard monomers: 30 parts methyl acrylate; Epoxy vinyl monomers: 8 parts glycidyl methacrylate; Heterocyclic functional monomers: 10 parts dicyclopentadiene acrylate; Crosslinking monomers: 4 parts acrylic acid; Initiator: 0.3 parts azobisisobutyronitrile; Catalyst: 1 part tetrabutylammonium bromide; Organic solvents: 40 parts toluene and 140 parts ethyl acetate.

[0080] In this embodiment, the preparation method of modified polyacrylate includes the following steps:

[0081] S1. Under an inert gas atmosphere, the soft monomer, hard monomer, epoxy-containing vinyl monomer, 1 / 2 mass of heterocyclic functional monomer and 1 / 2 mass of second organic solvent are stirred evenly, 1 / 4 mass of initiator is added first, and the reaction is carried out at 67°C for 1.5 h to obtain the first reaction solution.

[0082] S2. Add the remaining 1 / 2 mass of the heterocyclic functional monomer and 1 / 4 mass of the initiator to the first reaction solution, stir the reaction at 70°C, control the addition time to be 1.5h, and continue the reaction for 1h after the addition is complete to obtain the second reaction solution.

[0083] S3. Add the remaining 1 / 2 mass of initiator to the second reaction solution, stir at 76°C for 4 hours to obtain the third reaction solution;

[0084] S4. Add the crosslinking monomer, catalyst, and the remaining 1 / 2 mass of the second organic solvent to the third reaction solution in sequence, and stir the reaction at 88°C for 4 hours to obtain modified polyacrylate.

[0085] Reference Figure 1 The image shows the infrared spectrum of the modified polyacrylate prepared in Example 1. It can be seen that it has a wavelength of 1634 cm⁻¹. -1 The characteristic peak of C=C stretching vibration appears at 3000 cm⁻¹. -1 A stretching vibration peak of =CH appears nearby, at 910 cm⁻¹. -1 The presence of characteristic absorption peaks of epoxy groups nearby confirms that the modified polyacrylate molecule contains both epoxy groups and carbon-carbon double bonds.

[0086] The polyacrylate prepared in this embodiment has a solid content of 30%, a weight-average molecular weight of 100w, and a glass transition temperature of -5℃.

[0087] An insulating film is prepared by the following method: the adhesive prepared above is applied to a PI substrate layer with a thickness of 100 μm using a doctor blade, the dry adhesive thickness is controlled to be 30 ± 1 μm, baked at 100°C for 5 min, and finally a release film with a thickness of 25 μm is laminated on the adhesive surface to form an insulating film.

[0088] Example 2

[0089] The only difference between this embodiment and Example 1 is that the raw material for preparing the modified polyacrylate contains 8 parts of 3,4-epoxycyclohexylmethyl methacrylate.

[0090] The polyacrylate prepared in this embodiment has a solid content of 31%, a weight-average molecular weight of 90w, and a glass transition temperature of -2℃.

[0091] Example 3

[0092] The only difference between this embodiment and Example 1 is that the raw material for preparing the modified polyacrylate contains 8 parts of 3,4-epoxycyclohexyl methacrylate as an epoxy vinyl monomer.

[0093] The modified polyacrylate prepared in this embodiment has a solid content of 33%, a weight-average molecular weight of 115w, and a glass transition temperature of -8℃.

[0094] Example 4

[0095] The only difference between this embodiment and Embodiment 1 is that the epoxy resin in the raw materials for preparing the photoalkali-producing UV curable adhesive is: 20 parts of E-44 epoxy resin and 10 parts of TTA21; the thiol is 20 parts of TMMP.

[0096] Comparative Example 1

[0097] The only difference between this example and Example 1 is that no epoxy-containing vinyl monomer is added to the raw materials for preparing the modified polyacrylate.

[0098] The modified polyacrylate prepared in this comparative example has a solid content of 31%, a weight-average molecular weight of 98w, and a glass transition temperature of -6℃.

[0099] Comparative Example 2

[0100] The only difference between this example and Example 1 is that no crosslinking monomer is added to the raw materials for preparing the modified polyacrylate.

[0101] The modified polyacrylate prepared in this comparative example has a solid content of 29%, a weight-average molecular weight of 102w, and a glass transition temperature of -8℃.

[0102] Comparative Example 3

[0103] The only difference between this example and Example 1 is that no heterocyclic functional monomers are added to the raw materials for preparing the modified polyacrylate.

[0104] The modified polyacrylate prepared in this comparative example has a solid content of 27%, a weight-average molecular weight of 102w, and a glass transition temperature of -7℃.

[0105] Comparative Example 4

[0106] The only difference between this example and Example 1 is that in the preparation of the photoalkali-producing UV-curable adhesive, the thiol is 20 parts of DPMP.

[0107] Comparative Example 5

[0108] The only difference between this example and Example 1 is that the epoxy resin used in the preparation of the photoalkali-producing UV curing adhesive is 30 parts of E-44 epoxy resin.

[0109] Comparative Example 6

[0110] The only difference between this example and Example 1 is that the photosensitizer ITX is not added in the preparation of the photoalkali-producing UV curable adhesive.

[0111] Performance testing

[0112] The insulating films prepared in Examples 1-4 and Comparative Examples 1-6 were subjected to performance tests. The test items and methods are as follows:

[0113] (1) 180° peel strength test: After UV irradiation, the insulating film is attached to the test Al plate within 10 min. After standing for 24 h, 72 h and 168 h respectively, the test is carried out according to GB / T 2792-1998 standard. The requirement is: >40N / inch;

[0114] (2) High temperature resistance test: After UV irradiation, the insulating film is left to stand at room temperature for 72 hours. The dimensions in the length and width directions are measured respectively. Then, it is baked at 200℃ for 60 minutes. After cooling to room temperature, the dimensions in the length and width directions are measured respectively. Then, the dimensional change rate before and after the test is calculated. Requirement: Maximum dimensional change rate <0.20%.

[0115] (5) Shear strength test: After UV irradiation, the insulating film is attached to the test Al plate within 10 min. After 72 h, it is tested according to GB / T7124-2008 standard. The requirement is: >10MPa;

[0116] (6) Insulation performance test: Under 500VDC, 60s conditions, measured according to GB / T 24343-2009 standard, the requirement is: insulation resistance > 1GΩ;

[0117] (7) High voltage resistance test: Under the condition of 1500VDC@60s, it shall not be broken down. Requirement: leakage current <0.2mA.

[0118] The test results are shown in Table 1 below:

[0119] Table 1

[0120]

[0121] As shown in Table 1, in Examples 1-4, after UV irradiation, the 180° peel force increased with the extension of the standing time. When the standing time exceeded 72 hours, the peel force remained almost unchanged, indicating that the UV-curable adhesive of the present invention was basically fully cured after 72 hours. After complete curing, the 180° peel force was >45 N / inch, the shear strength was >10 MPa, and the heat shrinkage rate was <0.20%, indicating that the insulating film prepared by the present invention has the advantages of relatively controllable curing time, high shear strength, and good high temperature resistance.

[0122] Compared with the above embodiments:

[0123] Comparative Example 1 did not contain epoxy-containing vinyl monomers, and Comparative Example 2 did not contain crosslinking monomers. The resulting modified polyacrylates could not contain both C=C and epoxy groups at the same time, and could not form an IPN structure with the curing of epoxy resin. This resulted in low peel strength and shear strength of the cured insulating film, and the performance was unqualified.

[0124] Comparative Example 3 did not contain heterocyclic functional monomers, which resulted in a decrease in the rigidity of the polyacrylate molecular chain and a lower cohesive strength. Consequently, the peel strength after curing was <40 N / inch and the shear strength was <9 MPa, which was unqualified.

[0125] The thiol added in Comparative Example 4 was DPMP, which contains 6 -SH molecules per molecule, resulting in a faster curing rate and a more difficult-to-control reaction speed. The cured adhesive layer was hard and brittle, with a peel force of <37 N / inch and a shear strength of <9.5 MPa, which was unqualified.

[0126] Comparative Example 5, which did not contain alicyclic epoxy resin, also resulted in a faster curing rate, a hard and brittle adhesive layer, a peel force of <41 N / inch, and a shear strength of <9.5 MPa, which was unqualified.

[0127] No photosensitizer was added in Comparative Example 6, resulting in a very slow curing rate. Even after standing for 7 days after light exposure, it was not fully cured and failed the performance test.

[0128] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A photo-alkali-generating UV-curable adhesive, characterized in that, It includes the following raw material components by weight: 100 parts modified polyacrylate, 25-35 parts epoxy resin, 15-25 parts thiol, 4-8 parts photoalkali-generating agent, 0.1-0.5 parts photosensitizer, 0.5-1.5 parts silane coupling agent, and 80-120 parts first organic solvent; The raw materials for preparing modified polyacrylate include, by weight: 20-40 parts of soft monomer, 20-40 parts of hard monomer, 5-10 parts of epoxy-containing vinyl monomer, 5-15 parts of dicyclopentadiene acrylate, 2.5-5 parts of crosslinking monomer, 0.2-0.6 parts of initiator, and 150-250 parts of second organic solvent. The modified polyacrylate has a solid content of 25%-35%, a weight-average molecular weight of 80w-120w, a glass transition temperature of -10℃ to 0℃, and its molecular structure contains both carbon-carbon double bonds and epoxy groups. The epoxy resin is composed of bisphenol A epoxy resin and alicyclic epoxy resin in a mass ratio of 1-3:1, wherein the epoxy equivalent of the bisphenol A epoxy resin is 180-240 g / mol and the epoxy equivalent of the alicyclic epoxy resin is 125-145 g / mol. The thiol is selected from either a trifunctional or a tetrafunctional thiol; The crosslinking monomer is selected from one of acrylic acid, methacrylic acid, and β-acryloyloxypropionic acid.

2. The photo-alkali-generating UV-curable adhesive according to claim 1, characterized in that, The soft monomer is selected from one or more of n-octyl acrylate, isooctyl methacrylate, n-butyl acrylate, lauryl acrylate, and octadecyl acrylate; The hard monomer is selected from one or more of methyl methacrylate and ethyl methacrylate; The epoxy-containing vinyl monomer is selected from one or more of glycidyl methacrylate, 3,4-epoxycyclohexyl methacrylate and 3,4-epoxycyclohexyl methacrylate. The initiator is selected from at least one of acyl peroxide initiators and azo compound initiators; The second organic solvent is selected from one or more of ethyl acetate, butyl acetate, and toluene.

3. The photo-alkali-generating UV-curable adhesive according to claim 1, characterized in that, The modified polyacrylate is prepared by the following method: S1. Under an inert gas atmosphere, the soft monomer, hard monomer, epoxy-containing vinyl monomer, part of dicyclopentadiene acrylate and part of the second organic solvent are stirred evenly. The initiator in the first part is added first, and the reaction is carried out at 66.5℃-67.5℃ for 1h-2h to obtain the first reaction solution. S2. Add the remaining dicyclopentadiene acrylate and the initiator from the second part to the first reaction solution, stir the reaction at 69℃-71℃, control the dropping time to 1.5h-2h, and continue the reaction for 0.5-1h after the dropping is completed to obtain the second reaction solution. S3. Add the remaining initiator from the third part to the second reaction solution, and stir the reaction at 75℃-78℃ for 3h-6h to obtain the third reaction solution. S4. Add the crosslinking monomer, catalyst, and the remaining portion of the second organic solvent to the third reaction solution in sequence, and stir the reaction at 85℃-90℃ for 3-5 hours to obtain the modified polyacrylate.

4. The photo-alkali-generating UV-curable adhesive according to claim 1, characterized in that, The photo-alkali-producing agent is selected from one of WPBG300, WPBG345, TJ-PBG-801, and O0396.

5. The photo-alkali-generating UV-curable adhesive according to claim 1, characterized in that, The photosensitizer is selected from one of ITX, DETX, amine sensitizer EPD, amine sensitizer OPD, TR-PSS-402, and TR-PSS-303; The silane coupling agent is selected from epoxy-containing silane coupling agents; The first organic solvent is selected from one or more of ethyl acetate, butyl acetate, and toluene.

6. A method for preparing a photo-alkali-generating UV-curable adhesive as described in any one of claims 1-5, characterized in that, The process includes the following steps: mixing 100 parts of modified polyacrylate, 25-35 parts of epoxy resin, 15-25 parts of thiol, 4-8 parts of photoalkali-generating agent, 0.1-0.5 parts of photosensitizer, 0.5-1.5 parts of silane coupling agent, and 80-120 parts of the first organic solvent according to the mass ratio, and stirring evenly to obtain the photoalkali-generating UV-curable adhesive.

7. An insulating film, characterized in that, It is prepared by the following method: the photo-alkali-generating UV curing adhesive as described in any one of claims 1-5 is uniformly coated on the insulating base film, baked at 80-120°C for 3-8 minutes, and then a release film is laminated on the adhesive surface to obtain the insulating film; When using this insulating film, first expose it to UVA light, then peel off the release film and attach the adhesive side of the insulating film to the object at room temperature, and let it stand until it is fully cured.

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