Electrolytic adhesive, preparation method thereof and electrolytic adhesive tape

Abstract

The invention relates to the technical field of adhesives, in particular to an electrolytic adhesive, a preparation method thereof and an electrolytic adhesive tape. The electrolytic adhesive provided by the invention comprises the following components in parts by weight: 80-120 parts of an adhesive main body; 1 to 10 parts of ionic liquid; 1.1 to 7 parts of an auxiliary agent; 100 to 300 parts of a solvent; wherein the adhesive main body is a carboxyl-free polymer. According to the invention, the adhesive main body is constructed by selecting the monomer without carboxyl, so that the carboxyl in the masterbatch structure and the cation of the ionic liquid are prevented from interacting under high-temperature and high-humidity conditions to release hydrogen ions, the phenomena that the colloid corrodes a metal adherend and the adhesive surface is bubbled are prevented from the source, and the weather resistance and the moisture resistance of the electrolytic adhesive are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and more particularly to an electrolytic adhesive, its preparation method, and an electrolytic adhesive tape. Background Technology

[0002] Electrolytic adhesive tape, with its unique electro-peeling properties, is widely used in industrial production, electronics manufacturing, and other fields, meeting routine needs such as temporary fixation and subsequent disassembly of electronic components. As industrial technology expands into complex environmental applications, the environmental tolerance requirements for electrolytic adhesive tape are increasing.

[0003] In existing technologies, conventional electro-peelable adhesive sheets, when bonded to metal surfaces, are prone to two major problems in high-temperature and high-humidity environments: first, corrosion occurs on the metal surface, as the high temperature and humidity accelerate the chemical reaction between the metal and surrounding substances, damaging the metal's surface structure and properties; second, blistering occurs on the adhesive surface, caused by changes in the internal composition of the adhesive due to high temperature and humidity, resulting in gases that cannot be released in time. These phenomena severely affect product quality and reliability, greatly limiting the application of electrolytic adhesive tapes in fields with high environmental tolerance requirements, such as outdoor electronic equipment and automotive engine compartment electronic components, becoming a key technical bottleneck restricting its expanded application scope. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing an electrolytic adhesive, its preparation method, and an electrolytic adhesive tape. By selecting carboxyl-free monomers to construct the adhesive matrix, the interaction between carboxyl groups in the masterbatch structure and ionic liquid cations under high temperature and high humidity conditions, which releases hydrogen ions, is avoided from the source. This prevents the phenomenon of colloid corrosion of metal adhered objects and blistering of the adhesive surface, and significantly improves the weather resistance and moisture resistance of the electrolytic adhesive.

[0005] Therefore, the first objective of the present invention is to provide an electrolytic adhesive.

[0006] A second objective of this invention is to provide a method for preparing an electrolytic adhesive.

[0007] To achieve the third objective of this invention, the technical solution of this invention provides an electrolytic adhesive tape.

[0008] In one technical solution of the present invention, an electrolytic adhesive comprises, by weight: 80-120 parts of adhesive body; 1-10 parts of ionic liquid; 1.1-7 parts of additives; and 100-300 parts of solvent; wherein the adhesive body is a polymer without carboxyl groups.

[0009] In one embodiment of the present invention, the adhesive body comprises, by weight, 65-95 parts of soft monomer and 5-35 parts of hard monomer; wherein the soft monomer is selected from at least one of methyl acrylate, ethyl acrylate, isooctyl acrylate, and butyl acrylate; and the hard monomer is selected from at least one of ethyl (meth)acrylate, isopropyl (meth)acrylate, amyl (meth)acrylate, vinyl acetate, N,N-dimethylmethacrylamide, and ethylene glycol methyl ether acrylate.

[0010] In one technical solution of the present invention, the additives include ion promoters and antioxidants. By weight, the additives include: ion promoter, 1-5 parts; antioxidant, 0.1-2 parts.

[0011] In one embodiment of the present invention, the ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; the ion promoter is polyethylene glycol; the antioxidant is 2,6-di-tert-butyl-p-cresol; and the solvent is selected from at least one of ethyl acetate and toluene.

[0012] To achieve the second objective of this invention, the technical solution of this invention provides a method for preparing an electrolytic adhesive as described in any of the above technical solutions, comprising the following steps: S100, mixing the raw materials for preparing the adhesive body, and carrying out a polymerization reaction under a protective atmosphere to obtain a first reactant; S200, mixing the first reactant, ionic liquid, additives and solvent evenly and degassing to obtain an electrolytic adhesive.

[0013] In one technical solution of the present invention, S100 specifically includes: S110, mixing the raw materials for preparing the adhesive body, heating the reaction system to a first temperature under a protective atmosphere, adding a portion of the initiator, and keeping it at the temperature to obtain a pre-reactant; S120, adding the remaining initiator to the pre-reactant, adjusting the reaction system to a second temperature, and refluxing to obtain a first reactant.

[0014] In one technical solution of the present invention, in S110, the first temperature is 60℃-70℃; in S110, the heat preservation time is 3h-5h; in S120, the second temperature is 70℃-80℃; in S120, the reflux time is 2h-4h.

[0015] To achieve the third objective of this invention, the technical solution of this invention provides an electrolytic adhesive tape, comprising a first release film, an adhesive film layer, and a second release film stacked sequentially, wherein the adhesive film layer is formed by curing an electrolytic adhesive prepared by any of the above technical solutions or by any of the above technical solutions' electrolytic adhesive preparation methods.

[0016] The technical solution provided by this invention can achieve at least one of the following effects: (1) Excellent weather and moisture resistance. By selecting carboxyl-free monomers to construct the adhesive body, the interaction between carboxyl groups and ionic liquid cations in the masterbatch structure to release hydrogen ions under high temperature and high humidity conditions is avoided. This prevents the phenomenon of colloid corrosion of metal adhered objects and blistering of adhesive surface from the root, and significantly improves the weather resistance and moisture resistance of electrolytic adhesive. (2) Strong adhesion stability: After storage in a high temperature and high humidity environment, the adhesion before powering on decreases only slightly, and after powering on, it still maintains a good de-adhesion effect, meeting the core requirements of temporary bonding and subsequent peeling. (3) The structure is stable and reliable. The ion promoter promotes the movement of anions and cations, which enhances the debonding effect. The antioxidant effectively prevents the adhesive from oxidizing and aging, extends the service life, and ensures that the adhesive layer is structurally stable and free from slippage during long-term storage and use. (4) The process is adapted to industrialization, the preparation method is simple, the process parameters such as copolymerization reaction temperature and time are easy to control, the coating, drying and curing process is adapted to existing production lines, and it is suitable for large-scale mass production. Detailed Implementation

[0017] The technical solutions of various embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments described in the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] An embodiment of the present invention provides an electrolytic adhesive, comprising, by weight: 80-120 parts of adhesive body; 1-10 parts of ionic liquid; 1.1-7 parts of additives; and 100-300 parts of solvent; wherein the adhesive body is a carboxyl-free polymer.

[0019] The fact that the adhesive body does not contain carboxyl groups fundamentally avoids the problem of releasing hydrogen ions from the reaction of traditional carboxyl-containing polymers with ionic liquid cations in high temperature and high humidity environments, completely solving the technical pain points of metal corrosion and adhesive blistering. The weight range of each component has been optimized: the proportion of the adhesive body ensures stable basic bonding performance, the amount of ionic liquid ensures ionic conductivity when energized without reducing the cohesive force of the adhesive layer due to excessive amount, and the ratio of additives and solvents ensures uniform dispersion of each component, avoiding local performance imbalance, and achieving a synergistic balance of bonding, electrolysis and weather resistance.

[0020] In some embodiments of this application, the adhesive body comprises, by weight, 65-95 parts of soft monomer and 5-35 parts of hard monomer; wherein the soft monomer is selected from at least one of methyl acrylate, ethyl acrylate, isooctyl acrylate, and butyl acrylate; and the hard monomer is selected from at least one of ethyl (meth)acrylate, isopropyl (meth)acrylate, amyl (meth)acrylate, vinyl acetate, N,N-dimethylmethacrylamide, and ethylene glycol methyl ether acrylate.

[0021] Further defining the composition and components of the adhesive body, the soft monomers account for a higher proportion than the hard monomers, providing the adhesive with excellent flexibility and initial adhesion, ensuring a tight bond with the adhered objects; the hard monomers enhance the mechanical strength and high-temperature resistance of the adhesive layer, preventing slippage of the adhesive layer under high-temperature conditions; at the same time, the chemical structure of specific monomers, such as the long-chain alkyl groups of butyl acrylate and the polar groups of N,N-dimethylmethacrylamide, can improve compatibility with ionic liquids and additives, ensure the uniformity of the adhesive layer, and reduce performance fluctuations.

[0022] In some embodiments of this application, the additives include ion promoters and antioxidants. By weight, the additives include: ion promoter, 1-5 parts; antioxidant, 0.1-2 parts.

[0023] Ion accelerators can reduce the migration resistance of anions and cations in ionic liquids, significantly improve the ion conduction efficiency during energization, and enable the adhesive layer to quickly de-adhere after energization, ensuring that the peel force is stably reduced to a low level. Antioxidants can capture free radicals generated in the adhesive layer during storage or use, inhibiting polymer oxidative degradation. Especially in high temperature and high humidity environments, they can extend the service life of adhesives and avoid the decrease in adhesion or embrittlement of the adhesive layer caused by oxidation. 1-5 parts of ion accelerator can effectively enhance ion migration without affecting the cohesive force of the adhesive layer, while 0.1-2 parts of antioxidant can fully exert the antioxidant effect without causing precipitation and contamination of the adhesive surface due to excessive amount.

[0024] In some embodiments of this application, the ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; the ion promoter is polyethylene glycol; the antioxidant is 2,6-di-tert-butyl-p-cresol; and the solvent is selected from at least one of ethyl acetate and toluene.

[0025] 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, as an ionic liquid, possesses excellent thermal stability and ionic conductivity, and is not easily decomposed at high temperatures, ensuring long-term stability of electrolytic performance. Polyethylene glycol exhibits excellent compatibility with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, which can further reduce ion migration resistance and synergistically improve electro-stripping efficiency with the ionic liquid. 2,6-Di-tert-butylphenol has strong antioxidant properties, especially significantly inhibiting the oxidative breakage of polymer chains. Ethyl acetate and toluene, as solvents, have strong dissolving power for the adhesive matrix, ionic liquid, and additives, ensuring that all components form a homogeneous solution, avoiding component separation during coating, and ensuring consistent film performance.

[0026] The present invention provides a method for preparing an electrolytic adhesive as described in any of the above embodiments, comprising the following steps: S100, mixing raw materials for preparing the adhesive body and performing a polymerization reaction under a protective atmosphere to obtain a first reactant; S200, mixing the first reactant, ionic liquid, additives and solvent evenly and degassing to obtain an electrolytic adhesive.

[0027] The protective atmosphere can isolate oxygen from interfering with the polymerization reaction, avoiding problems such as low monomer conversion rate and wide molecular weight distribution of polymer caused by oxygen as a polymerization inhibitor, and ensuring the structural stability of the adhesive body; the degassing step after mixing can effectively remove air bubbles in the system, preventing pinholes or depressions from forming after the adhesive is coated and filmed, ensuring a smooth film surface and uniform adhesion, and improving the product qualification rate.

[0028] In some embodiments of this application, S100 specifically includes: S110, mixing the raw materials for preparing the adhesive body, heating the reaction system to a first temperature under a protective atmosphere, adding a portion of the initiator, and maintaining the temperature to obtain a pre-reactant; S120, adding the remaining initiator to the pre-reactant, adjusting the reaction system to a second temperature, and refluxing to obtain a first reactant.

[0029] Adding the initiator in stages can control the polymerization rate and avoid excessively vigorous reactions caused by adding the initiator all at once. This reduces the problem of uneven molecular weight distribution of the polymer and ensures the stability of the main adhesive properties. Combining the pre-reaction and reflow reaction allows most monomers to polymerize steadily at a lower temperature first, and then reflow promotes the full reaction of the remaining monomers, improves the monomer conversion rate, and reduces the negative impact of unreacted monomers on the adhesive layer properties.

[0030] In some embodiments of this application, in S110, the first temperature is 60℃-70℃; in S110, the heat preservation time is 3h-5h; in S120, the second temperature is 70℃-80℃; in S120, the reflux time is 2h-4h.

[0031] The first temperature is the optimal decomposition temperature range of the initiator, which can ensure stable initiation efficiency in the pre-reaction stage and avoid slow reaction due to excessively low temperature or excessively high temperature leading to rapid consumption of the initiator. The holding time ensures that the pre-reaction is fully carried out, allowing the polymer chain to initially grow. The second temperature and reflux time specifically promote the reaction of residual monomers, while reflux removes the heat of reaction, avoiding polymer degradation caused by local overheating, and finally obtaining an adhesive matrix with a narrow molecular weight distribution and uniform performance.

[0032] An embodiment of the present invention provides an electrolytic adhesive tape, comprising a first release film, an adhesive film layer, and a second release film stacked sequentially, wherein the adhesive film layer is formed by curing an electrolytic adhesive prepared by any of the above embodiments or by any of the above embodiments' electrolytic adhesive preparation methods.

[0033] The double-layer release film protects the adhesive film layer from both sides, preventing contamination of the adhesive surface during storage or transportation and ensuring the initial performance stability of the adhesive film. The layered structure design is suitable for continuous industrial production, and the film can be directly bonded to the object by peeling off the release film, making it easy to use. The adhesive film layer is formed by curing the aforementioned electrolytic adhesive, inheriting the core advantages of excellent weather resistance and stable electrolytic performance. It can be directly applied to complex environments such as outdoor electronic equipment and automotive engine compartments, meeting the dual needs of temporary fixation and efficient disassembly.

[0034]

Example 1

[0035] Electrolytic adhesive is coated on the release surface of the first release film, and then dried in an oven at 50°C for 5 minutes and in an oven at 120°C for 5 minutes. After drying, the release surface of the second release film is attached, and the film is cured in an oven at 50°C for 2 days to obtain an electrolytic adhesive tape. The thickness of the electrolytic adhesive film is 40 μm, and both the first and second release films are lightweight release films.

[0036]

Example 2

[0037]

Example 3

[0038]

Example 4

[0039]

Example 5

[0040]

Example 6

[0041]

Example 7

[0042]

Example 8

[0043] Comparative Example 1 The preparation method for this comparative example is the same as in Example 1, except that in S100, ethyl (meth)acrylate is replaced with methacrylic acid.

[0044] Comparative Example 2 The preparation method for this comparative example is the same as in Example 1, except that in S100, ethyl (meth)acrylate is replaced with acrylic acid.

[0045] Comparative Example 3 The preparation method for this comparative example is the same as in Example 1, except that no ion promoter was added in S200.

[0046] Comparative Example 4 The preparation method for this comparative example is the same as in Example 1, except that no antioxidant was added in S200.

[0047] Comparative Example 5 The preparation method of this comparative example is the same as that in Example 1, except that in S200, the mass fraction of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is 11 parts.

[0048] Performance testing 1. Peel strength before electrolysis at room temperature: The sample size of the electrolytic adhesive film was 25mm × 100mm, with a thickness of 40μm. A 20μm thick aluminum foil was attached to the back of the test surface. The sample was then attached to a 6-series aluminum plate, with a covered area of ​​25mm × 80mm. A 2kg roller was used to roll the sample back and forth three times at a speed of 120mm / s, and the environment was kept at room temperature and humidity. After 30 minutes, the 180° peel strength was tested on a tensile testing machine.

[0049] 2. Peel strength under energized conditions at room temperature: The sample size of the electrolytic adhesive film was 25mm × 100mm, with a thickness of 40μm. A 20μm thick aluminum foil was attached to the back of the test surface. The sample was then attached to a 6-series aluminum plate, with a covered area of ​​25mm × 80mm. A 2kg roller was used to roll the sample back and forth three times at a speed of 120mm / s, while the environment was kept at room temperature and humidity. After 30 minutes, the positive terminal of a DC power supply was connected to the conductive substrate, and the negative terminal was connected to the aluminum plate. A 9V DC current was applied for 60 seconds. After the power was applied, the 180° peel strength was quickly tested on a tensile testing machine.

[0050] 3. High-Temperature Holding Strength: The sample size of the electrolytic adhesive film is 25mm × 100mm, with a thickness of 40μm. A 25μm thick PET film is attached to the back of the test surface. The sample is then attached to a stainless steel plate, with a coverage area of ​​25mm × 25mm. A 2kg roller is used to roll the sample back and forth three times at a speed of 120mm / s, followed by a 30-minute resting period. The end of the sample is fixed, and a 1kg weight is attached. The environment is maintained at 70℃. After 24 hours, the sample is observed to see if it detaches from the stainless steel plate. If the sample detaches from the stainless steel plate, the time from placement to detachment is recorded. If the sample does not detach from the stainless steel plate but slips, the slip distance is recorded.

[0051] 4. Peel strength before electrolysis under high temperature and humidity: The sample size of the electrolytic adhesive film is 25mm × 100mm, with a thickness of 40μm. A 20μm thick aluminum foil is attached to the back of the test surface. The sample is then attached to a 6-series aluminum plate with a coverage area of ​​25mm × 80mm. A 2kg roller is used to roll the sample back and forth three times at a speed of 120mm / s. The environment is 60℃ and 95% humidity. After 144 hours, the sample is allowed to stand at room temperature for 2 hours before the 180° peel strength is tested on a tensile testing machine.

[0052] 5. Peel strength under high temperature and humidity conditions: The sample size of the electrolytic adhesive film was 25mm × 100mm, with a thickness of 40μm. A 20μm thick aluminum foil was attached to the back of the test surface. The sample was then attached to a 6-series aluminum plate, with a covered area of ​​25mm × 80mm. A 2kg roller was used to roll the sample back and forth three times at a speed of 120mm / s. The environment was 60℃ and 95% humidity. After 144 hours, the sample was allowed to stand at room temperature for 2 hours. Then, the positive terminal of a DC power supply was connected to the conductive substrate, and the negative terminal was connected to the aluminum plate. A 12V DC current was applied for 60 seconds. After the current was applied, the peel strength at 180° was quickly tested on a tensile testing machine.

[0053] 6. Corrosion evaluation: Visually assess the corrosion area and draw a rectangle with a pencil to enclose the corrosion area, which is recorded as area A; test the rubber strip (25mm×80mm) and record it as area B.

[0054] Corrosion area ratio = A / B.

[0055] 7. Bubbling condition: Visually assess the bubbling area. Draw a rectangle with a pencil to enclose the corroded area and record it as area C; test the adhesive strip (25mm×80mm) and record it as area B. Bubble area ratio = C / B.

[0056] Table 1

[0057] According to the test results in the table above, the electrolytic adhesives and electrolytic tapes provided in Examples 1-5, 7, and 8 all exhibited excellent comprehensive performance: the peel force before energization at room temperature was stable at 1670gf / 25mm-1745gf / 25mm, and the peel force after energization was ≤45gf. After high-temperature and high-humidity aging, the peel force before energization decreased by ≤10%, and all examples showed no corrosion or blistering. Comparative Examples 1-2, due to the use of carboxyl-containing monomers, although the electrolytic bonding effect at room temperature and after aging was acceptable, showed a corrosion area ratio of 34%-40% and a blistering area ratio of 50%-56% after aging. In Comparative Example 3, without the addition of an ion promoter, the peel force of its electrolytic tape after energization reached 115gf / 25mm-130gf / 25mm, far exceeding the ≤45gf of the examples, indicating that the ion promoter is crucial for improving ion migration efficiency and ensuring the electrolytic bonding effect. In Comparative Example 4, no ion promoter was added. After aging under high temperature and humidity, the peel strength of the antioxidant before energization decreased from 1715 gf / 25 mm at room temperature to 1505 gf / 25 mm, a decrease of 12.2%, which is significantly higher than the ≤10% in the example. This proves that the antioxidant can effectively inhibit polymer oxidative degradation and improve the aging resistance stability of the adhesive. In Comparative Example 5, the ionic liquid was 11 parts. Although the electrolytic adhesive tape prepared had good electrolytic debonding effect, the high temperature holding strength showed a 2 mm slip, indicating that excessive ionic liquid would lead to a decrease in the cohesive force of the adhesive layer.

[0058] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and not restrictive in all respects. The scope of the invention is defined by the appended claims, not by the foregoing description, and thus all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

[0059] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An electrolytic adhesive, characterized in that, The electrolytic adhesive comprises, by weight, parts of: Adhesive base, 80-120 parts; Ionic liquid, 1-10 parts; Additives, 1.1 to 7 parts; Solvent, 100-300 parts; The adhesive is primarily a carboxyl-free polymer.

2. The electrolytic adhesive according to claim 1, characterized in that, The adhesive body comprises, by weight, the following: Soft monomers, 65-95 parts; 5-35 parts of hard monomer; The soft monomer is selected from at least one of methyl acrylate, ethyl acrylate, isooctyl acrylate, and butyl acrylate; The hard monomer is selected from at least one of ethyl (meth)acrylate, isopropyl (meth)acrylate, amyl (meth)acrylate, vinyl acetate, N,N-dimethylmethacrylamide, and ethylene glycol methyl ether acrylate.

3. The electrolytic adhesive according to claim 1, characterized in that, The adjuvants include ion promoters and antioxidants, and by weight, the adjuvants include: Ion promoter, 1-5 parts; Antioxidant, 0.1 to 2 parts.

4. The electrolytic adhesive according to claim 3, characterized in that, The ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; The ion promoter is polyethylene glycol; the antioxidant is 2,6-di-tert-butyl-p-cresol. The antioxidant is 2,6-di-tert-butyl-p-cresol; The solvent is selected from at least one of ethyl acetate and toluene.

5. A method for preparing an electrolytic adhesive as described in any one of claims 1-4, characterized in that, Includes the following steps: S100. The raw materials for preparing the adhesive body are mixed and polymerized under a protective atmosphere to obtain the first reactant. S200: Mix the first reactant, ionic liquid, additive and solvent evenly and degas to obtain the electrolytic adhesive.

6. The preparation method according to claim 5, characterized in that, S100 specifically includes: S110. Mix the raw materials for preparing the adhesive body, heat the reaction system to a first temperature under a protective atmosphere, add a portion of the initiator, keep the temperature, and obtain the pre-reactant. S120. Add the remaining initiator to the pre-reactant, adjust the reaction system to the second temperature, and reflux to obtain the first reactant.

7. The preparation method according to claim 6, characterized in that, In S110, the first temperature is 60℃-70℃; In S110, the heat preservation time is 3-5 hours; In S120, the second temperature is 70℃-80℃; In S120, the reflux time is 2h-4h.

8. An electrolytic adhesive tape, characterized in that, It comprises a first release film, an adhesive film layer, and a second release film stacked sequentially, wherein the adhesive film layer is formed by curing the electrolytic adhesive according to any one of claims 1-4 or the electrolytic adhesive prepared by the preparation method according to any one of claims 5-7.

Images