Electrically peelable adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of adhesives, and particularly relates to an electrically peelable adhesive and a preparation method thereof. The invention provides an electrically peelable adhesive which comprises the following raw materials in parts by weight: 70-80 parts of an acrylic acid system pressure-sensitive adhesive; 10 to 20 parts of 1, 3-dibutyl imidazole cyanamide salt ionic liquid; 5-10 parts of a plasticizer; 0.5 to 1 part of a stabilizer; and 5-10 parts of a filler. According to the electro-stripping adhesive disclosed by the invention, the acrylic acid system pressure-sensitive adhesive and the 1, 3-dibutylimidazole cyanamide salt ionic liquid are compounded, so that the bonding strength and reversibility are effectively improved, meanwhile, the environmental reliability is enhanced, and the preparation cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives. More specifically, it relates to an electro-responsive release adhesive and a preparation method thereof. Background Art

[0002] With the continuous progress of technology, the performance requirements for materials in various industries are getting higher and higher. Especially in the fields of electronics, automotive, aerospace, etc., the demand for adhesives is also increasing day by day, especially in some occasions where frequent disassembly and repair are required. After traditional adhesives are applied for bonding, they often cannot be peeled off as needed, resulting in huge waste of resources due to the inability to disassemble and repair the bonded parts, which is not conducive to the long-term sustainable development of the bonding field. Therefore, developing an adhesive that can be quickly and conveniently peeled off when needed has become an important research direction.

[0003] As a new type of functional material, electro-responsive release adhesives can achieve rapid electro-responsive on-demand peeling under the application of voltage by introducing ionic carriers such as ionic liquids and deep eutectic solvents into the polymer matrix. Without using chemical solvents, it will not cause damage to the components, greatly reducing the difficulty and risk of disassembly and improving work efficiency.

[0004] In the electrical and electronics industries, electro-responsive release adhesives are crucial for the safe installation and maintenance of sensitive electronic components. For example, using conductive adhesives to adhere electronic components to printed circuit boards (PCBs) will greatly simplify the disassembly and replacement of faulty components. The adhesive can also be remotely triggered without direct contact with the components.

[0005] However, it is difficult to balance the bonding strength and reversibility of existing electro-responsive release adhesives, and it is difficult to achieve both high bonding strength and convenient debonding at the same time. Moreover, in some environments, such as high temperature, humidity and other conditions, problems such as decreased bonding performance and aging may occur, affecting their service life and reliability. The existing preparation methods of electro-responsive release adhesives are often costly and the processes are complex, which limits their popularization in practical applications.

[0006] The present invention aims to improve the bonding strength and reversibility of electro-responsive release adhesives by improving their formulations and preparation methods, while enhancing their environmental reliability and reducing the preparation cost to solve the problems existing in the prior art. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects and deficiencies existing in the prior art, and to provide an electro-strippable adhesive and a preparation method thereof. An electro-strippable adhesive provided by the present invention, by weight, the adhesive comprises the following raw materials: acrylic pressure-sensitive adhesive: 70-80 parts; 1,3-dibutylimidazolium cyanamide ionic liquid: 10-20 parts; plasticizer: 5-10 parts; stabilizer: 0.5-1 part; filler: 5-10 parts. The electro-strippable adhesive of the present invention effectively improves the bonding strength and reversibility by adopting the composite of acrylic pressure-sensitive adhesive and 1,3-dibutylimidazolium cyanamide ionic liquid, while enhancing the environmental reliability and reducing the preparation cost.

[0008] The object of the present invention is to provide an electro-strippable adhesive.

[0009] Another object of the present invention is to provide a preparation method of an electro-strippable adhesive.

[0010] The above object of the present invention is achieved by the following technical solutions:

[0011] An electro-strippable adhesive, by weight, the adhesive comprises the following raw materials:

[0012] Acrylic pressure-sensitive adhesive: 70-80 parts;

[0013] 1,3-dibutylimidazolium cyanamide ionic liquid: 10-20 parts;

[0014] Plasticizer: 5-10 parts;

[0015] Stabilizer: 0.5-1 part;

[0016] Filler: 5-10 parts.

[0017] Preferably, the plasticizer is dioctyl phthalate (DOP); the stabilizer is antioxidant 1010; the filler is nano-SiO2.

[0018] In the present invention, in a preferred technical solution, the preparation method of the 1,3-dibutylimidazolium cyanamide ionic liquid comprises the following steps: (1) Dissolve imidazole in acetonitrile, then add sodium bicarbonate and 4-bromobutane, and stir and react overnight under reflux condensation; after the reaction is completed, cool the mixture, filter, remove the solvent, then wash the crude product with methyl tert-butyl ether and ethyl acetate respectively, then dissolve it in dichloromethane, dry it with magnesium sulfate, add activated carbon and stir, filter and remove the solvent to obtain 1,3-dibutyl-1H-imidazole-3-bromide;

[0019] (2) Dissolve the 1,3-dibutyl-1H-imidazol-3-bromide prepared in step (1) in acetone, add sodium cyanamide, stir overnight at room temperature, filter and remove the solvent under vacuum. Dissolve the residue in dichloromethane, dry with magnesium sulfate, filter to remove the solvent, and then wash the product with methyl tert-butyl ether and dry to constant weight to obtain 1,3-dibutylimidazolium cyanamide ionic liquid.

[0020] Further, in step (1), the mass ratio of imidazole, sodium bicarbonate, and 4-bromobutane is 1:1.4 - 1.6:4 - 5; the reaction temperature for condensation reflux is 70 - 90 °C.

[0021] Further, in step (2), the mass ratio of 1,3-dibutyl-1H-imidazol-3-bromide to sodium cyanamide is 1:0.3 - 0.4; the drying temperature is 60 - 80 °C.

[0022] In the present invention, a further preferred technical solution is that the preparation method of the acrylic pressure-sensitive adhesive includes the following steps: Mix acrylate monomers, functional monomers, and hard monomers in proportion, then add an initiator in a solvent and stir and react at 60 - 80 °C for 6 hours to form a prepolymer, and then remove the solvent to obtain an acrylic pressure-sensitive adhesive.

[0023] Further, the acrylate monomer is at least one of butyl acrylate (BA), isooctyl acrylate (2-EHA), and ethyl acrylate (EA); the functional monomer is at least one of acrylic acid (AA), methacrylic acid (MAA), and 2-hydroxyethyl acrylate (HEA); the hard monomer is at least one of methyl methacrylate (MMA) and styrene (St); the initiator is at least one of benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN); the solvent is at least one of ethyl acetate, toluene, and acetone.

[0024] Further, the mass ratio of the acrylate monomer, functional monomer, and hard monomer is 70 - 90:5 - 10:5 - 15.

[0025] Based on the above preparation method of an electro-strippable adhesive, the preparation method includes the following steps:

[0026] Mix the acrylic pressure-sensitive adhesive with 1,3-dibutylimidazolium cyanamide ionic liquid, stir to form a homogeneous mixture, then add a plasticizer and a stabilizer, continue to stir for 10 - 20 minutes, and then add a filler. After stirring evenly, form a film by extrusion molding or solution casting.

[0027] Preferably, the stirring temperature is 60 - 80 °C, the stirring time is 10 - 20 min; the continuous stirring time is 10 - 20 min.

[0028] The present invention has the following beneficial effects:

[0029] The electro - detachable adhesive of the present invention, by using the composite of acrylic - based pressure - sensitive adhesive and 1,3 - dibutylimidazolium cyanamide ionic liquid, effectively improves the bonding strength and reversibility, while enhancing the environmental reliability and reducing the preparation cost.

[0030] (1) High bonding strength: By optimizing the formula, the bonding strength is improved, meeting the high bonding requirements in practical applications.

[0031] (2) Good reversibility: By applying a voltage, the ions in the ionic liquid migrate under the action of an electric field, resulting in an electrochemical reaction at the interface between the adhesive and the substrate, forming oxidation or reduction products. These products weaken the adhesion between the adhesive and the substrate, thus achieving debonding. The ionic liquid can also catalyze the transesterification reaction at high temperatures, further promoting the debonding of the adhesive. The operation is simple and does not damage the bonded parts.

[0032] (3) Strong environmental reliability: The ionic liquid has good thermal stability and electrochemical stability, and can maintain the performance of the adhesive in high - temperature and humid environments. Fillers (such as nano - silica SiO2) can improve the high - temperature and moisture - resistant properties of the adhesive, enhancing its bonding performance in harsh environments. Therefore, in high - temperature, humid and other environments, the bonding performance is stable and the service life is long.

[0033] (4) Simple preparation process and low cost: The preparation method is simple, the cost is low, and it is easy to realize industrial production.

[0034] (5) High flexibility and mechanical strength: By adding plasticizers, they can be evenly dispersed in the adhesive to form a strengthened network structure, improving the mechanical strength and wear resistance of the adhesive. By adding fillers, they can be evenly dispersed in the adhesive to form a strengthened network structure, improving the mechanical strength and wear resistance of the adhesive, and further improving the flexibility and mechanical strength of the adhesive.

[0035] (6) Good thermal stability: By adding stabilizers, they can capture the free radicals generated by the adhesive at high temperatures, preventing the oxidation and degradation reactions initiated by free radicals, thus improving the thermal stability of the adhesive. Therefore, the adhesive has high thermal stability and antioxidant performance. Description of the Drawings

[0036] Figure 1 is a cross - sectional view of the electro - detachable adhesive. Detailed Embodiments

[0037] The present invention will be further described below in conjunction with specific embodiments, but the embodiments do not impose any form of limitation on the present invention. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0038] Figure 1 Among them, the conductive layer includes metal materials, conductive polymers, carbon materials, and composite materials. The metal materials include copper and aluminum, and the conductive polymers include polyaniline, polypyrrole, and polythiophene; the carbon materials include graphene, carbon nanotubes, and activated carbon; the composite materials include metal-polymer composites, carbon-polymer composites, and metal-carbon composites. The conductive layer serves as an electrode for applying voltage or current to trigger the electro-responsive behavior of the adhesive.

[0039] The dielectric layer includes polyimide (PI), polyethylene (PE), and other high dielectric strength polymers. The dielectric layer can isolate the conductive layer from the adhesive layer to prevent direct current penetration and cause short circuits, while controlling the electric field to concentrate on the adhesive interface.

[0040] The electro-responsive peeling adhesive layer undergoes ion migration or chemical bond breakage under the action of an electric field to achieve controllable debonding.

[0041] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0042] Example 1

[0043] An electro-responsive peeling adhesive, by weight, the adhesive comprises the following raw materials:

[0044] Acrylic pressure-sensitive adhesive: 70 parts;

[0045] 1,3-Dibutylimidazolium cyanamide ionic liquid: 20 parts;

[0046] Plasticizer: 5 parts;

[0047] Stabilizer: 1 part;

[0048] Filler: 5 parts.

[0049] The plasticizer is dioctyl phthalate (DOP); the stabilizer is antioxidant 1010; the filler is nano-SiO2.

[0050] The preparation method of the 1,3-dibutylimidazolium cyanamide ionic liquid comprises the following steps: (1) Dissolve 10 g of imidazole in 200 mL of acetonitrile, then add 14.5 g of sodium bicarbonate and 45 g of 4-bromobutane, and stir and react overnight under reflux condensation at 80 °C; after the reaction is completed, cool the mixture, filter, remove the solvent, then wash the crude product with 250 mL of methyl tert-butyl ether and 250 mL of ethyl acetate respectively, then dissolve it in 250 mL of dichloromethane, dry it with 25 g of magnesium sulfate, add 12.5 g of activated carbon and stir, filter and remove the solvent to obtain 1,3-dibutyl-1H-imidazole-3-bromide;

[0051] (2) Dissolve 25 g of the 1,3-dibutyl-1H-imidazole-3-bromide prepared in step (1) in 250 mL of acetone, add 8.75 g of sodium cyanamide, stir overnight at room temperature, filter and remove the solvent under vacuum conditions, dissolve the residue in 250 mL of dichloromethane, dry it with 13 g of magnesium sulfate, filter and remove the solvent, then wash the product with 250 mL of methyl tert-butyl ether, and dry it to constant weight at 70 °C to obtain the 1,3-dibutylimidazolium cyanamide ionic liquid.

[0052] The preparation method of the acrylic pressure-sensitive adhesive comprises the following steps: Mix 80 g of isooctyl acrylate, 8 g of methacrylic acid and 10 g of styrene in proportion, then add an appropriate amount of benzoyl peroxide to 250 mL of toluene, and stir and react at 70 °C for 6 hours to form a prepolymer, and then remove the solvent to obtain the acrylic pressure-sensitive adhesive.

[0053] The preparation method of the electro-eliminable adhesive comprises the following steps:

[0054] Mix the acrylic pressure-sensitive adhesive with the 1,3-dibutylimidazolium cyanamide ionic liquid, stir at 70 °C for 15 minutes to form a homogeneous mixture, then add a plasticizer and a stabilizer, continue to stir for 15 minutes, then add a filler, stir evenly, and prepare a film by extrusion molding or solution casting. Apply voltage: 9 V. Debonding time: 1 minute. It can recover its adhesiveness after waiting for 40 s and can be reused 5 times.

[0055] Example 2

[0056] The difference between Example 2 and Example 1 is that: for an electro-eliminable adhesive, by weight, the adhesive comprises the following raw materials:

[0057] Acrylic pressure-sensitive adhesive: 75 parts;

[0058] 1,3-dibutylimidazolium cyanamide ionic liquid: 15 parts;

[0059] Plasticizer: 8 parts;

[0060] Stabilizer: 0.7 parts;

[0061] Filler: 7 parts.

[0062] Example 3

[0063] The difference between Example 3 and Example 1 is that: for an electro-strippable adhesive, by weight, the adhesive comprises the following raw materials:

[0064] Acrylic pressure-sensitive adhesive: 80 parts;

[0065] 1,3-dibutylimidazolium cyanamide ionic liquid: 10 parts;

[0066] Plasticizer: 10 parts;

[0067] Stabilizer: 0.5 parts;

[0068] Filler: 10 parts.

[0069] Comparative Example 1

[0070] The difference between Comparative Example 1 and Example 1 is that: for an electro-strippable adhesive, by weight, the adhesive comprises the following raw materials:

[0071] Acrylic pressure-sensitive adhesive: 101 parts.

[0072] Comparative Example 2

[0073] The difference between Comparative Example 2 and Example 1 is that: for an electro-strippable adhesive, by weight, the adhesive comprises the following raw materials:

[0074] Acrylic pressure-sensitive adhesive: 81 parts;

[0075] 1,3-dibutylimidazolium cyanamide ionic liquid: 20 parts.

[0076] Comparative Example 3

[0077] The difference between Comparative Example 3 and Example 1 is that: for an electro-strippable adhesive, by weight, the adhesive comprises the following raw materials:

[0078] Acrylic pressure-sensitive adhesive: 76 parts;

[0079] 1,3-dibutylimidazolium cyanamide ionic liquid: 20 parts;

[0080] Plasticizer: 5 parts.

[0081] Comparative Example 4

[0082] The difference between Comparative Example 4 and Example 1 is that: for an electro-strippable adhesive, by weight, the adhesive comprises the following raw materials:

[0083] Acrylic pressure - sensitive adhesive: 75 parts;

[0084] 1,3 - dibutylimidazolium cyanamide ionic liquid: 20 parts;

[0085] Plasticizer: 5 parts;

[0086] Stabilizer: 1 part.

[0087] Comparative Example 5

[0088] The difference between Comparative Example 5 and Example 1 is that: an equal amount of 1 - butyl - 3 - methylimidazolium chloride is used to replace 1,3 - dibutylimidazolium cyanamide ionic liquid.

[0089] Test the performance of Examples 1 - 3 and Comparative Examples 1 - 5. When Examples 1 - 3 and Comparative Examples 1 - 5 are cast, the mass of the adhesives used is the same, and the thickness of the cast films is 0.3 mm. The specific results are as follows, see Table 1:

[0090] Table 1

[0091]

[0092] It can be seen from Table 1 that by comparing Example 1 with Comparative Examples 1 - 5, it can be seen that for the electro - stripping adhesive prepared by the present invention, the maximum tensile strength can reach 52.67 MPa, and the maximum elongation at break can reach 137.22%. Compared with Comparative Example 1, the tensile strength: increased by 11.29 MPa, with an increase rate of 27.3%; the elongation at break: increased by 126.38%, with an increase rate of 1166.7%. By comparing Example 1 with Comparative Examples 2 - 5, it can be seen that the ionic liquid, plasticizer, stabilizer and filler added in the present invention significantly improve the tensile strength and elongation at break.

[0093] Test the tensile strength of Example 1 and Comparative Examples 1 and 5 at 80 °C, the tensile strength at 90% RH humidity, and the thermal decomposition temperature. The specific results are shown in Table 2:

[0094] Table 2

[0095]

[0096] It can be seen from Table 2 that for the electro - stripping adhesive prepared by the present invention, after adding ionic liquid, plasticizer, stabilizer and filler, the bonding stability and thermal stability are significantly improved.

[0097] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. An electro-strippable adhesive, characterized in that: By weight parts, the binder comprises the following raw materials: Acrylic pressure-sensitive adhesive: 70 - 80 parts; 1,3 - dibutylimidazolium cyanamide ionic liquid: 10 - 20 parts; Plasticizer: 5 - 10 parts; Stabilizer: 0.5 - 1 part; Filler: 5 - 10 parts.

2. The electro-strippable adhesive according to claim 1, characterized in that: The plasticizer is dioctyl phthalate (DOP); the stabilizer is antioxidant 1010; the filler is nano - SiO₂.

3. A kind of electro - strippable adhesive according to claim 1, characterized in that: The preparation method of the 1,3 - dibutylimidazolium cyanamide ionic liquid comprises the following steps: (1) Dissolve imidazole in acetonitrile, then add sodium bicarbonate and 4 - bromobutane, and stir - react overnight under the condition of condensation reflux; after the reaction is completed, cool the mixture, filter, remove the solvent, then wash the crude product with methyl tert - butyl ether and ethyl acetate respectively, then dissolve it in dichloromethane, dry it with magnesium sulfate, add activated carbon and stir, filter and remove the solvent to obtain 1,3 - dibutyl - 1H - imidazole - 3 - bromide; (2) Dissolve the 1,3 - dibutyl - 1H - imidazole - 3 - bromide prepared in step (1) in acetone, add sodium cyanamide, stir overnight at room temperature, filter and remove the solvent under vacuum conditions, dissolve the residue in dichloromethane, dry it with magnesium sulfate, filter and remove the solvent, then wash the product with methyl tert - butyl ether, and dry it to constant weight to obtain 1,3 - dibutylimidazolium cyanamide ionic liquid.

4. The electro - strippable adhesive according to claim 3, wherein: In step (1), the mass ratio of imidazole, sodium bicarbonate, and 4 - bromobutane is: 1:1.4 - 1.6:4 - 5; the reaction temperature of the condensation reflux is 70 - 90 °C.

5. The electro-strippable adhesive according to claim 3, wherein: In step (2), the mass ratio of 1,3 - dibutyl - 1H - imidazole - 3 - bromide to sodium cyanamide is 1:0.3 - 0.4; the drying temperature is 60 - 80 °C.

6. The electro-strippable adhesive according to claim 1, wherein: The preparation method of the acrylic pressure - sensitive adhesive comprises the following steps: Mix acrylate monomers, functional monomers, and hard monomers in proportion, then add an initiator in a solvent, and stir - react at 60 - 80 °C for 6 hours to form a prepolymer, and then remove the solvent to obtain the acrylic pressure - sensitive adhesive.

7. The electro - strippable adhesive according to claim 6, wherein: The acrylate monomers are at least one of butyl acrylate (BA), 2 - ethylhexyl acrylate (2 - EHA), and ethyl acrylate (EA); the functional monomers are at least one of acrylic acid (AA), methacrylic acid (MAA), and 2 - hydroxyethyl acrylate (HEA); the hard monomers are at least one of methyl methacrylate (MMA) and styrene (St); the initiator is at least one of benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN); the solvent is at least one of ethyl acetate, toluene, and acetone.

8. The electro-strippable adhesive according to claim 6, wherein: The mass ratio of the acrylate monomers, functional monomers, and hard monomers is 70 - 90:5 - 10:5 - 15.

9. The preparation method of an electro-strippable adhesive according to any one of claims 1-8, characterized in that: The preparation method comprises the following steps: Mix the acrylic pressure - sensitive adhesive with the 1,3 - dibutylimidazolium cyanamide ionic liquid, stir to form a homogeneous mixture, then add the plasticizer and the stabilizer, continue to stir for 10 - 20 minutes, then add the filler, stir evenly, and prepare a film by extrusion molding or solution casting method.

10. The preparation method of an electro-strippable adhesive according to claim 9, characterized in that: The stirring temperature is 60 to 80 °C, and the stirring time is 10 to 20 minutes; the subsequent stirring time is 10 to 20 minutes.

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