Pressure-sensitive adhesive for pasting mica plate as well as preparation method and application of pressure-sensitive adhesive

Abstract

The invention relates to a pressure-sensitive adhesive for pasting a mica plate as well as a preparation method and application thereof, the pressure-sensitive adhesive for pasting the mica plate comprises glue, and the glue comprises the following raw material components in parts by mass: 90-95 parts of a soft monomer; 6-10 parts of a functional monomer; 0.8-0.9 part of an initiator and a solvent, so that the solid content of the glue is 40%-50%; comprising 10-12 parts by mass of low softening point resin and 0.01-0.02 part by mass of a curing agent, based on 100 parts by mass of the glue, the use amount of the low softening point resin is 10-12 parts by mass, and the use amount of the curing agent is 0.01-0.02 part by mass. The pressure-sensitive adhesive is good in stripping force and retention force when being attached to a mica plate, and can meet the attachment requirement of the mica plate.

Description

Technical Field

[0001] The invention relates to the field of adhesives, and in particular to a pressure-sensitive adhesive for pasting mica boards, a preparation method thereof, and an application thereof. Background Art

[0002] Mica is a layered silicate mineral material characterized by excellent insulation, high-temperature resistance, and chemical stability. Mica can be divided into natural mica and synthetic mica. Due to the limited resources of natural mica, synthetic mica is more widely used. Mica sheets are produced from mica through a high-temperature melting process and can be used as thermal insulation materials in applications such as new energy vehicles. While mica sheets have excellent physical and chemical properties, they also have some disadvantages: a) weak interlayer bonding and easy delamination; b) uneven surface and low surface energy. These disadvantages also lead to problems such as difficulty in wetting and penetrating the mica sheets, as well as poor adhesion when pressure-sensitive adhesive tape is applied to the mica sheets. Due to the weak interlayer bonding, poor cohesion, rough surface, and low surface energy of mica sheets, high requirements are placed on the pressure-sensitive adhesive tape used for mica sheets. The pressure-sensitive adhesive used for mica sheets must have both good wettability and creep resistance to ensure that the adhesive layer can penetrate deeper into the multiple mica sheets, ensuring a complete and stable assembly. However, existing pressure-sensitive adhesives cannot well meet the requirements for laminating mica boards. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the first purpose of the present invention is to provide a pressure-sensitive adhesive for bonding mica boards, which has good performance in peeling force and holding force when bonded to mica boards and can meet the bonding requirements with mica boards.

[0004] The second object of the present invention is to provide a method for preparing the pressure-sensitive adhesive, which can optimize the bonding performance of the mica board pressure-sensitive adhesive tape.

[0005] The third object of the present invention is to provide applications of the pressure-sensitive adhesive.

[0006] To achieve the first objective of the present invention, the present invention provides a pressure-sensitive adhesive for mica boards, which includes glue. The glue includes the following raw material components in parts by mass: 90 to 95 parts of a soft monomer; 6 to 10 parts of a functional monomer; 0.8 to 0.9 parts of an initiator; and a solvent, so that the solid content of the glue is 40% to 50%.

[0007] In some embodiments of the present invention, the glue comprises the following raw material components in parts by mass: 92 parts of soft monomer; 8 parts of functional monomer; 0.85 parts of initiator; and a solvent such that the solid content of the glue is 45%, the solvent including 92 parts of solvent used in the polymerization process of the soft monomer, functional monomer and initiator and an additional solvent used to adjust the solid content after the polymerization reaction.

[0008] In some embodiments of the present invention, the soft monomer is one or more of ethyl acrylate, butyl acrylate, and isooctyl acrylate, preferably a mixture of butyl acrylate and isooctyl acrylate, more preferably the mass ratio of butyl acrylate to isooctyl acrylate is 5:(13~18), and most preferably the mass ratio of butyl acrylate to isooctyl acrylate is 5:18.

[0009] In some embodiments of the present invention, the functional monomer is one or more of methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl acrylate, and hydroxypropyl acrylate, preferably acrylic acid.

[0010] In some embodiments of the present invention, the solvent is one or more of ethyl acetate, toluene or 2-butanone, preferably ethyl acetate.

[0011] In some embodiments of the present invention, the initiator is one or more of dibenzoyl peroxide, azobisisobutyronitrile, and azobisisoheptylonitrile, preferably azobisisobutyronitrile.

[0012] In some embodiments of the present invention, the pressure-sensitive adhesive for mica board also includes a low softening point resin and a curing agent. Taking the glue as 100 parts by mass, the amount of the low softening point resin is 10 to 12 parts by mass, and the amount of the curing agent is 0.01 to 0.02 parts by mass.

[0013] In some embodiments of the present invention, based on 100 parts by mass of the glue, the amount of the low softening point resin is 11.25 parts by mass, and the amount of the curing agent is 0.017 parts by mass.

[0014] In some embodiments of the present invention, the low softening point resin is selected from one or more of hydrogenated rosin resin, pentaerythritol rosin ester, and slash pine glycerol ester.

[0015] In some embodiments of the present invention, the curing agent is an epoxy compound.

[0016] In some embodiments of the present invention, the low softening point resin is a mixture of slash pine glycerol ester and rosin pentaerythritol ester, and preferably the mass ratio of slash pine glycerol ester to rosin pentaerythritol ester is 1.5:1 to 1:1.5.

[0017] To achieve the second purpose of the present invention, the present invention provides a method for preparing a pressure-sensitive adhesive for mica boards as described in any of the above-mentioned schemes, which includes preparing glue: putting part of the soft monomer, part of the functional monomer, and the first part of the solvent into a reactor, adding the first part of the initiator when the temperature is raised to a first preset temperature under nitrogen protection, and starting to uniformly add a mixed solution of the remaining soft monomer, the remaining functional monomer, and the second part of the solvent after the reaction for the first preset time period, and the addition is completed within the second preset time period, during which the second part of the initiator is added in batches; after the addition is completed, the third part of the initiator is added and the temperature is raised to reflux, the temperature is maintained for the third preset time period, the remaining initiator is added, the reflux reaction is continued for the fourth preset time period, the temperature is reduced to below 40°C, and additional solvent is added to adjust the solid content of the glue.

[0018] In some embodiments of the present invention, the mass ratio of the partial soft monomers to the remaining soft monomers is (1-1.3):1, preferably 1:1.

[0019] In some embodiments of the present invention, when the soft monomer is a mixture of multiple soft monomers, the mass ratio of each soft monomer in the portion of soft monomers to the remaining soft monomers is preferably 1:1.

[0020] In some embodiments of the present invention, the mass ratio of the partial functional monomers to the remaining functional monomers is (1-1.3):1, preferably 1:1.

[0021] In some embodiments of the present invention, the mass ratio of the first part of solvent to the second part of solvent is (40-50):1, preferably 45:1;

[0022] In some embodiments of the present invention, the mass ratio of the first part of initiator, the second part of initiator, the third part of initiator and the remaining initiator is 1:(1.4-1.6):(3.1-3.2):(4-6), preferably 1:1.5:3.125:5.

[0023] In some embodiments of the present invention, the first preset temperature is 66±1°C.

[0024] In some embodiments of the present invention, the first preset time period is 50 minutes, the second preset time period is 120 minutes, the third preset time period is 1 hour, and the fourth preset time period is 3.5 hours.

[0025] In some embodiments of the present invention, the preparation method further comprises uniformly mixing the glue, the low softening point resin and the curing agent.

[0026] To achieve the third purpose of the present invention, the present invention provides a pressure-sensitive adhesive tape for affixing mica boards, which includes a substrate and a pressure-sensitive adhesive layer provided on both sides of the substrate. The preparation method of the pressure-sensitive adhesive layer includes: coating the pressure-sensitive adhesive described in any of the above schemes on two sides of release paper, curing, and then laminating it to the substrate and maturing.

[0027] To achieve the third purpose of the present invention, the present invention also provides a mica board composite material, which includes a mica board and a pressure-sensitive adhesive bonded to the mica board, and the pressure-sensitive adhesive is the pressure-sensitive adhesive tape of any of the above solutions.

[0028] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0029] The pressure-sensitive adhesive for mica board bonding provided by the present invention exhibits excellent bonding properties on mica board surfaces with microscopically rough structures. The adhesive flows through multiple layers of mica boards, filling microscopic gaps and thereby forming a strong anchoring effect. The present invention utilizes a specific monomer ratio to increase the fluidity of the adhesive, meeting the low viscosity and appropriate curing speed requirements for adhesives used to bond mica boards. Polar groups in the adhesive, such as the carbonyl group of acrylates and the carboxyl group of acrylic acid, can form weak electrostatic adsorption with siloxanes on the mica board surface. Hydroxyl or carboxyl groups can also form hydrogen bonds with trace hydroxyl groups on the mica board surface, increasing adhesion. Furthermore, the present invention utilizes a low-softening-point resin, enabling the adhesive to be quickly and effectively bonded to the mica board. The use of an epoxy curing agent allows for cross-linking to form chemical bonds, improving the stability and bonding durability of the pressure-sensitive adhesive without compromising wettability. This allows the adhesive to generate strong van der Waals forces and chemical bonds with the functional groups on the mica board surface, ensuring complete and stable bonding of the mica board assembly.

[0030] The present invention provides a method for producing a pressure-sensitive adhesive for mica sheets. By optimizing the process flow and monomer addition ratio, and employing a stepwise dropwise polymerization method, the molecular weight and molecular weight distribution of the adhesive are adjusted, resulting in an adhesive layer with excellent spreadability, enabling deeper penetration into multi-layer mica sheets. Overall, the pressure-sensitive adhesive produced by the present invention exhibits excellent peel strength and retention, meeting the requirements for lamination to mica sheets. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of the pressure-sensitive adhesive embodiment of the present invention.

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0033] The pressure-sensitive adhesive of the present invention and its application in affixing mica boards will be further described below with reference to specific embodiments.

[0034] 1. Preparation of glue for pressure-sensitive adhesive

[0035] The following preparation examples first prepare glue for a pressure-sensitive adhesive.

[0036] Among them, the glue of the pressure-sensitive adhesive of Preparation Examples 1 to 3 was prepared by the following method: part of the soft monomer, part of the functional monomer, and 90 parts of the solvent were put into the reactor, and 0.08 parts of the initiator were added when the temperature was raised to 66±1°C under nitrogen protection. After 50 minutes, the mixed solution was added dropwise at a uniform rate. The mixed solution was a mixture of the remaining soft monomer, the remaining functional monomer, and 2 parts of the solvent. The addition was completed in 120 minutes, and 0.04 parts of the initiator were added in three batches during this period; after the addition was completed, 0.25 parts of the initiator were added and the temperature was raised to reflux, kept warm for 1 hour, the remaining 0.4 parts of the initiator were added, the reflux reaction was continued for 3.5 hours, the temperature was lowered to below 40°C, and additional ethyl acetate was added as a solvent to adjust the solid content of the synthesized glue to 45%.

[0037] To better demonstrate the advantages of the step-by-step dropwise polymerization method, Preparation Example 4 was set up. The pressure-sensitive adhesive glue of Preparation Example 4 was prepared by another method: all soft monomers, functional monomers, and solvents were placed in a reactor. Under nitrogen protection, 0.25 parts of initiator were added when the temperature was raised to 66±1°C. After 3 hours, 0.2 parts of initiator were added in three batches at 1 hour intervals. The reflux reaction was continued for 2.5 hours, and the temperature was lowered to below 40°C. Additional ethyl acetate was added as a solvent to adjust the solid content of the synthesized glue to 45%.

[0038] The specific formulations (parts by mass) of the glues of the pressure-sensitive adhesives of Preparation Examples 1 to 4 are shown in Table 1.

[0039] Table 1 Glue formula and viscosity of Preparation Examples 1 to 4

[0040]

[0041] The preparation examples in Table 1 show that the pressure-sensitive adhesives prepared in Preparation Examples 2, 3, and 4 exhibited relatively high viscosities, resulting in insufficient wettability when laminating mica sheets. The pressure-sensitive adhesive prepared in Preparation Example 1 exhibited moderate viscosity, achieving both wettability and durability when laminating mica sheets. Furthermore, Table 1 demonstrates that the stepwise dropwise polymerization method facilitates adjustment of molecular weight and molecular weight distribution, resulting in an adhesive layer with excellent spreadability and deeper penetration into multi-layer mica sheets.

[0042] 2. Preparation of Double-Sided Pressure-Sensitive Tape

[0043] To the pressure-sensitive adhesive prepared in Preparation Example 1, 11.25% by weight of a low-softening-point resin and 0.017% by weight of a curing agent were added. After stirring evenly, the adhesive was coated onto the first and second release papers. The adhesive was cross-linked and cured at 65°C and 110°C for 2 and 3 minutes, respectively. The adhesive was then bonded to a substrate and aged at 60°C for 48 hours. The low-softening-point resin was a mixture of slash pine glycerol ester and rosin pentaerythritol ester.

[0044] The mass fractions of the components of the coating compositions of Examples 1 to 4 are specifically shown in Table 2. The "acrylate adhesive" in Table 2 is the glue of the acrylate adhesive obtained in Preparation Example 1.

[0045] Table 2 Coating composition formulations of Examples 1 to 4

[0046]

[0047] To better illustrate the performance of the pressure-sensitive adhesive for mica boards according to the present invention, the compositions of Examples 5 to 8 were prepared. In Example 5, 11.25% by weight of a single low-softening point resin and 0.017% by weight of a curing agent were added to the acrylic adhesive prepared in Preparation Example 1. In Example 6, 11.25% by weight of a high-softening point resin (polymerized rosin) and 0.017% by weight of a curing agent were added to the acrylic adhesive prepared in Preparation Example 1. In Example 7, 0.017% by weight of a curing agent was added to the acrylic adhesive prepared in Preparation Example 1, without any resin added. In Example 8, 11.25% by weight of a mixed low-softening point resin and 0.017% by weight of a curing agent were added to the acrylic adhesive prepared in Preparation Example 4. The specific weight percentages of the components in the coating compositions of Examples 5 to 8 are shown in Table 3.

[0048] Table 3 Formulations of coating compositions of Examples 5 to 8

[0049]

[0050] like Figure 1 As shown, the coating compositions of the examples in Table 2 and Table 3 were stirred uniformly and then coated onto the first and second release papers. The compositions were cross-linked and cured at 65°C and 110°C for 2 minutes and 3 minutes, respectively. The compositions were then laminated to a substrate 3 and aged at 60°C for 48 hours to form a double-sided pressure-sensitive adhesive tape having first and second pressure-sensitive adhesive layers 2 and 4 on both sides of the substrate 3, and first and second release layers 1 and 5 on the outer sides of the first and second pressure-sensitive adhesive layers 2 and 4. The substrate 3 of the double-sided pressure-sensitive adhesive tape was 12 μm thick PET, and the first and second pressure-sensitive adhesive layers 2 and 4 on both sides of the substrate 3 were 64 μm thick, respectively.

[0051] 3. Peel and hold strength test of pressure-sensitive tape on mica board

[0052] This embodiment also provides the application of the pressure-sensitive adhesive to the mica board.

[0053] Peel strength test: The 180° peel strength of the pressure-sensitive adhesive was tested according to the GB / T 2792-2014 test standard. The laminating sheet was a mica sheet and the laminating time was changed to 2 hours.

[0054] Holding force test: Test the holding force of pressure sensitive adhesive according to GB / T 4851-2014 test standard.

[0055] The above performance test results are shown in Table 4:

[0056] Table 4 Performance test results

[0057]

[0058] The data in Tables 2, 3, and 4 demonstrate that, as can be seen from a comparison between Examples 1-4 and Examples 5-7, the addition of a low-softening point resin significantly improves the pressure-sensitive adhesive's adhesion to mica sheets. The addition of two low-softening point resins significantly enhances the tape's adhesion to mica compared to using only one resin alone. Furthermore, Example 1 exhibits superior performance compared to Example 8, both with the same resin ratio. This demonstrates the potential for improved performance of the acrylate adhesive raw material prepared using the prepolymerization-drip addition process of the present invention. This is because the prepolymerization-drip addition process allows for a more uniform chemical composition of acrylate components with varying reactivity (reactivity ratios) during polymerization. Furthermore, this process also results in a more uniform molecular weight distribution during polymerization, thereby reducing the overall viscosity of the polymer, facilitating subsequent tape preparation and demonstrating excellent mica adhesion. Overall, the pressure-sensitive adhesive prepared in Example 1 exhibits excellent peel strength and holding power, meeting the requirements for lamination to mica sheets. This also shows that the combination of two low-softening-point resins and the addition of a certain amount of epoxy compound curing agent can effectively adhere the pressure-sensitive adhesive to the mica board.

[0059] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A pressure-sensitive adhesive for mica board, characterized in that The glue comprises the following raw material components in parts by mass: Soft monomer 90~95 parts; 6-10 parts of functional monomer; 0.8~0.9 parts of initiator, Solvent, so that the solid content of the glue is 40% to 50%.

2. The pressure-sensitive adhesive for mica board according to claim 1, characterized in that The glue comprises the following raw material components in parts by mass: 92 parts of a soft monomer; 8 parts of a functional monomer; 0.85 parts of an initiator; and a solvent such that the solid content of the glue is 45%, the solvent comprising 92 parts of a solvent used in the polymerization process of the soft monomer, the functional monomer, and the initiator, and an additional solvent used to adjust the solid content after the polymerization reaction.

3. A pressure-sensitive adhesive for mica board according to claim 1 or 2, characterized in that The soft monomer is one or more of ethyl acrylate, butyl acrylate, and isooctyl acrylate, preferably a mixture of butyl acrylate and isooctyl acrylate, more preferably the mass ratio of butyl acrylate to isooctyl acrylate is 5:(13-18), most preferably the mass ratio of butyl acrylate to isooctyl acrylate is 5:18; The functional monomer is one or more of methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl acrylate, and hydroxypropyl acrylate, preferably acrylic acid; The solvent is one or more of ethyl acetate, toluene or 2-butanone, preferably ethyl acetate; The initiator is one or more of dibenzoyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile, preferably azobisisobutyronitrile.

4. A pressure-sensitive adhesive for mica board according to claim 1 or 2, characterized in that It also includes a low softening point resin and a curing agent. Taking the glue as 100 parts by mass, the amount of the low softening point resin is 10-12 parts by mass, and the amount of the curing agent is 0.01-0.02 parts by mass.

5. The pressure-sensitive adhesive for mica board according to claim 4, characterized in that Taking the glue as 100 parts by mass, the amount of the low softening point resin is 11.25 parts by mass, and the amount of the curing agent is 0.017 parts by mass; The low softening point resin is selected from one or more of hydrogenated rosin resin, rosin pentaerythritol ester, and slash pine glycerol ester; The curing agent is an epoxy compound.

6. The pressure-sensitive adhesive for mica board according to claim 5, characterized in that The low softening point resin is a mixture of slash pine glycerol ester and rosin pentaerythritol ester, and preferably the mass ratio of slash pine glycerol ester to rosin pentaerythritol ester is 1.5:1 to 1:1.

5.

7. The method for preparing a pressure-sensitive adhesive for mica board according to any one of claims 1 to 6, characterized in that Including preparation of glue: Put part of the soft monomer, part of the functional monomer and the first part of the solvent into a reactor, and add the first part of the initiator when the temperature is raised to the first preset temperature under nitrogen protection. After the reaction for the first preset time period, start to uniformly add the mixed solution of the remaining soft monomer, the remaining functional monomer and the second part of the solvent, and complete the addition within the second preset time period, during which the second part of the initiator is added in batches; after the addition is completed, add the third part of the initiator and heat the reactor to reflux, keep the temperature for the third preset time period, add the remaining initiator, continue the reflux reaction for the fourth preset time period, cool to below 40°C, and then add additional solvent to adjust the solid content of the glue.

8. The method for preparing a pressure-sensitive adhesive for mica board bonding according to claim 7, characterized in that: The mass ratio of the partial soft monomer to the remaining soft monomer is (1-1.3):1, preferably 1:1; when the soft monomer is a mixture of multiple soft monomers, the mass ratio of each soft monomer in the partial soft monomer to the remaining soft monomer is preferably 1:1; The mass ratio of the partial functional monomer to the remaining functional monomer is (1-1.3):1, preferably 1:1; The mass ratio of the first part of solvent to the second part of solvent is (40-50):1, preferably 45:1; The mass ratio of the first part of initiator, the second part of initiator, the third part of initiator and the remaining initiator is 1: (1.4-1.6): (3.1-3.2): (4-6), preferably 1: 1.5: 3.125: 5; The fractional batches are divided into 3 to 4 batches; The first preset temperature is 66±1°C; The first preset time period is 50 minutes, the second preset time period is 120 minutes, the third preset time period is 1 hour, and the fourth preset time period is 3.5 hours; The preparation method further comprises uniformly mixing the glue, the low softening point resin and the curing agent.

9. A pressure-sensitive adhesive tape for mica board, characterized in that The invention comprises a substrate and a pressure-sensitive adhesive layer provided on both sides of the substrate; the preparation method of the pressure-sensitive adhesive layer comprises: coating the pressure-sensitive adhesive for mica board according to any one of claims 1 to 6 or the pressure-sensitive adhesive prepared by the preparation method according to claim 7 or 8 on two sides of release paper, curing the coating, and then laminating the coating to the substrate and maturing the coating.

10. A mica board composite material, characterized in that The invention comprises a mica board and a pressure-sensitive adhesive bonded to the mica board, wherein the pressure-sensitive adhesive is the pressure-sensitive adhesive for bonding mica boards as described in any one of claims 1 to 6, or the pressure-sensitive adhesive prepared by the preparation method described in claim 7 or 8, or the pressure-sensitive adhesive tape described in claim 9.

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