High-heat-resistance acrylate adhesive and preparation method thereof

Abstract

The invention relates to the technical field of adhesives, in particular to a high-heat-resistance acrylate adhesive and a preparation method thereof.The high-heat-resistance acrylate adhesive is prepared from a component A, a component B and a component C; the component A is prepared from the following raw materials in parts by weight: 10 to 40 parts of a soft monomer, 10 to 30 parts of a hard monomer, 1 to 4 parts of a functional monomer, 40 to 55 parts of ethyl acetate, 0.1 to 1 part of an initiator and 0.05 to 0.4 part of a molecular chain transfer agent; the component B is an epoxy resin composition; and the component C is an organic solvent. The acrylate adhesive prepared by the invention has excellent performance in the aspects of excessive glue, peel strength and heat resistance, and meets the high-temperature process requirements of electronic manufacturing.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a high heat-resistant acrylate adhesive and its preparation method. Background Technology

[0002] As modern industrial manufacturing upgrades its demand for "efficient connection" from "basic fixation" to "high precision, high reliability, and multi-scenario adaptability," adhesives, with their ability to overcome the connection limitations of different materials (such as metals, polymer films, and composite materials) and their advantages such as lightweight, low assembly stress, and compatibility with automated processes, have gradually become core auxiliary materials in equipment assembly, and their application coverage continues to expand.

[0003] Acrylic adhesives, as one of the mainstream categories in the structural adhesive field, play a key role in various industries due to their wide range of bonding substrates, curing efficiency suitable for industrial production, and balanced mechanical properties. For example, Chinese invention patent application CN113402989A provides an acrylic adhesive that extends the adhesive's shelf life, facilitating large-area, long-term adhesive application to acrylic products. However, in electronic manufacturing, reflow soldering processes at temperatures above 300°C are often required. Traditional adhesives are prone to defects such as bulging and peeling, failing to meet high-temperature stability requirements. Furthermore, the bonding interface with substrates such as polyimide, electrolytic copper, and stainless steel is prone to cracking, affecting product reliability. In addition, adhesive overflow is difficult to control during the lamination process; excessive overflow can lead to pore blockage, while insufficient overflow can result in bonding gaps. Summary of the Invention

[0004] To address the problems in the prior art, the first aspect of the present invention provides a high heat-resistant acrylate adhesive, the raw materials of which include component A, component B and component C; The raw materials for preparing component A, by weight, include 10-40 parts of soft monomer, 10-30 parts of hard monomer, 1-4 parts of functional monomer, 40-55 parts of ethyl acetate, 0.1-1 parts of initiator and 0.05-0.4 parts of chain transfer agent; Component B is an epoxy resin composition; component C is an organic solvent.

[0005] In one embodiment, the mass ratio of component A, component B, and component C is (6.5-8.5):1:1.5. Examples include 6.5:1:1.5, 7:1:1.5, 7.5:1:1.5, and 8:1:1.5.

[0006] In one embodiment, the soft monomer includes at least one of butyl acrylate, ethyl acrylate, and isooctyl acrylate.

[0007] In one embodiment, the soft monomer comprises butyl acrylate and ethyl acrylate, wherein the mass ratio of butyl acrylate to ethyl acrylate is (10-20):(10-20).

[0008] In one embodiment, the hard monomer includes at least one of acrylonitrile and isobornyl methacrylate.

[0009] In one embodiment, the mass ratio of acrylonitrile to isobornyl methacrylate is (5-10):(10-20).

[0010] In one embodiment, the functional monomer contains a rigid cyclic group.

[0011] In one embodiment, the functional monomer comprises glycidyl methacrylate.

[0012] In one embodiment, the initiator comprises azobisisobutyronitrile.

[0013] In one embodiment, the chain transfer agent comprises mercaptoacetic acid.

[0014] In one embodiment, the epoxy resin composition comprises liquid epoxy resin and o-cresol epoxy resin.

[0015] In one embodiment, the mass ratio of the liquid epoxy resin to the o-cresol epoxy resin is (20-45):(40-65).

[0016] In one embodiment, the mass ratio of the liquid epoxy resin to the o-cresol epoxy resin is (30-45):(50-65).

[0017] In one embodiment, the organic solvent is a mixture of hexamethylenediamine and ethanol, wherein the mass ratio of hexamethylenediamine to ethanol is (1-5):(25-95).

[0018] A second aspect of this invention provides a method for preparing a high heat-resistant acrylate adhesive, comprising the following steps: S1. Mix the soft monomer, hard monomer and functional monomer evenly to obtain a monomer mixture; S2. Dissolve the initiator in ethyl acetate to obtain an initiator solution; S3. At 65°C, add 1 / 3 mass of monomer mixture and 1 / 3 mass of initiator solution dropwise. Stir for 1-2 hours, then add the remaining monomer mixture and initiator solution dropwise. Raise the temperature to 75°C and stir for 2-3 hours. Control the temperature at 85°C and stir for 3-4 hours. Raise the temperature to 110°C, add chain transfer agent, and react for 0.5-1 hours. Cool to room temperature and filter to obtain component A. S4. Heat component A and component B to 40-50°C and stir until homogeneous, then cool to room temperature. Add component C and stir at room temperature for 0.5-1 h to obtain the high heat-resistant acrylic adhesive.

[0019] In one embodiment, step S1 includes: preheating isobornyl methacrylate to 40°C-50°C to dissolve it, then adding butyl acrylate, ethyl acrylate, acrylonitrile, and glycidyl methacrylate and stirring until homogeneous to obtain a monomer mixture.

[0020] In one embodiment, the viscosity of component A is adjusted to 1500±200 mPa·s (25°C) using ethyl acetate.

[0021] In one embodiment, the preparation method of component B includes: heating o-cresol epoxy resin to 80°C to melt it, then adding liquid epoxy resin and stirring at 300 rpm for 20 minutes at 75°C until it becomes uniform and transparent, thereby obtaining component B.

[0022] In one embodiment, the dripping rate in step S3 is 2-5 mL / min.

[0023] Beneficial effects 1. The high heat-resistant acrylate adhesive provided by the present invention is composed of components A, B and C. By controlling the ratio of raw materials and the addition of isobornyl methacrylate and glycidyl methacrylate, the prepared acrylate adhesive resin has excellent high temperature resistance, rapid curing and high bonding strength.

[0024] 2. This invention selects glycidyl methacrylate, a functional monomer with rigid cyclic groups, because its rigid cyclic groups can inhibit the high-temperature movement of molecular chains and significantly increase the glass transition temperature. At the same time, azobisisobutyronitrile (AIBN) is used as an initiator for the polymerization of acrylic monomers to achieve high initiation efficiency. Compared with peroxides (such as BPO), AIBN is less inhibited by oxygen. The preparation process only requires nitrogen gas for 30 minutes to effectively remove oxygen, reduce the energy consumption in the prepolymerization stage, and make the peel strength and heat resistance of the entire system better.

[0025] 3. The introduction of o-cresol epoxy resin into component B of this invention can significantly improve the heat resistance, chemical stability and bonding strength of the adhesive after being compounded with component A. Its high cross-linking density phenolic skeleton can greatly improve thermal stability. At the same time, the addition of liquid epoxy resin can ensure its compatibility, thereby ensuring matching with the subsequent curing process.

[0026] 4. The present invention controls the mass ratio of component A, component B and component C to be (6.5-8.5):1:1.5. The adhesive prepared under this mass ratio can ensure excellent performance in terms of glue overflow, peel strength and heat resistance.

[0027] 5. The acrylate adhesive provided by this invention has high peel strength, with peel strengths to polyimide (PI), electrolytic copper (ED copper), and stainless steel substrates reaching 17 N / cm or more, 23 N / cm or more, and 17 N / cm or more, respectively, and stable interfacial adhesion; at the same time, it has excellent reflow soldering heat resistance, meeting the high-temperature process requirements of electronic manufacturing. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention. Experimental methods not specifying specific conditions in the embodiments were performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0029] The relevant information regarding the raw materials used in this application is as follows: Butyl acrylate, CAS No.: 141-32-2, from Aladdin Biochemical Technology Co., Ltd.; Ethyl acrylate, CAS No.: 140-88-5, from Aladdin Biochemical Technology Co., Ltd.; Acrylonitrile, CAS No.: 107-13-1, from AccuStandard; Liquid epoxy resin, CAS No.: 25068-38-6, from Zhaochang Chemical (Shanghai) Co., Ltd.; o-Cresol-formaldehyde epoxy resin, CAS No.: 29690-82-2, from Jinan Shengquan Group Co., Ltd.; Glycidyl methacrylate, CAS No.: 2095-03-6, from Chengdu Yuanda; Isoborneol methacrylate, CAS No.: 5888-33-5, from Anaiji Chemical; Ethyl acetate, CAS No.: 141-78-6, from Aladdin Biochemical Technology Co., Ltd.; Azobisisobutyronitrile, CAS No.: 78-67-1, from Aladdin Biochemical Technology Co., Ltd.; Mercaptoacetic acid, CAS No.: 68-11-1, from Sigma-Aldrich.

[0030] Example 1 The first aspect of this example provides a high heat-resistant acrylic adhesive, the raw materials of which include component A, component B and component C; The raw materials for preparing component A, by weight, include 29 parts soft monomer, 16 parts hard monomer, 4 parts functional monomer, 50 parts ethyl acetate, 0.9 parts initiator and 0.1 parts chain transfer agent; Component B consists of liquid epoxy resin and o-cresyl epoxy resin; the mass ratio of the liquid epoxy resin to the o-cresyl epoxy resin is 40:60.

[0031] Component C is an organic solvent. The organic solvent is a mixture of hexamethylenediamine and ethanol, wherein the mass ratio of hexamethylenediamine to ethanol is 2:70.

[0032] The mass ratio of components A, B, and C is 7.5:1:1.5.

[0033] The soft monomers are butyl acrylate and ethyl acrylate, and the mass ratio of butyl acrylate to ethyl acrylate is 16:13.

[0034] The hard monomers are acrylonitrile and isobornyl methacrylate, and the mass ratio of acrylonitrile to isobornyl methacrylate is 6:10.

[0035] The functional monomer is glycidyl methacrylate.

[0036] The initiator is azobisisobutyronitrile.

[0037] The chain transfer agent is mercaptoacetic acid.

[0038] The second aspect of this example provides a method for preparing a high heat-resistant acrylic adhesive, comprising the following steps: S1. After preheating isobornyl methacrylate to 45°C to dissolve, add it together with butyl acrylate, ethyl acrylate, acrylonitrile, and glycidyl methacrylate into a reaction vessel, stir and mix evenly, control the speed at 200 rpm, and stir for 10 min to obtain a monomer mixture. S2. Dissolve the initiator in ethyl acetate to obtain an initiator solution; continuously purge the reactor with nitrogen gas for 30 min at a flow rate of 1 L / min; S3. After nitrogen gas is introduced, 1 / 3 mass of monomer mixture and 1 / 3 mass of initiator solution are added dropwise at 65°C. After stirring for 1 hour, the remaining monomer mixture and initiator solution are added dropwise. The temperature is raised to 75°C and stirred for 2 hours. The temperature is controlled at 85°C and stirred for 3 hours. The temperature is then raised to 110°C, and a molecular chain transfer agent is added. The reaction is carried out for 0.5 hours. The viscosity is adjusted to 1500 mPa·s (25°C). The mixture is then cooled to room temperature and filtered to obtain component A. S4. Heat component A and component B to 45°C and stir until homogeneous, then cool to room temperature. Add component C and stir at room temperature for 0.5 hours to obtain the high heat-resistant acrylic adhesive.

[0039] The preparation method of component B includes: heating o-cresol epoxy resin to 80°C to melt it, then adding liquid epoxy resin and stirring at 300 rpm for 20 minutes at 75°C until it becomes uniform and transparent, thereby obtaining component B.

[0040] The dripping rate in step S3 is 2 mL / min.

[0041] Example 2 The specific implementation method of this example is the same as that of Example 1, except that the soft monomer is butyl acrylate and ethyl acrylate, and the mass ratio of butyl acrylate to ethyl acrylate is 17:12.

[0042] Example 3 The specific implementation method of this example is the same as that of Example 1, except that the soft monomer is butyl acrylate and ethyl acrylate, and the mass ratio of butyl acrylate to ethyl acrylate is 11:18.

[0043] Example 4 The specific implementation method of this example is the same as that of Example 1, except that the soft monomer is butyl acrylate and ethyl acrylate, and the mass ratio of butyl acrylate to ethyl acrylate is 19:10.

[0044] Example 5 The specific implementation method of this example is the same as that of Example 1, except that component B is liquid epoxy resin and o-crestoaldehyde epoxy resin; the mass ratio of liquid epoxy resin to o-crestoaldehyde epoxy resin is 35:65.

[0045] Comparative Example 1 The specific implementation method in this example is the same as in Example 1, except that, according to the weight parts, the raw materials for preparing component A include 31 parts of soft monomer, 14 parts of hard monomer, 4 parts of functional monomer, 50 parts of ethyl acetate, 0.9 parts of initiator and 0.1 parts of chain transfer agent.

[0046] The soft monomers are butyl acrylate and ethyl acrylate, and the mass ratio of butyl acrylate to ethyl acrylate is 19:12.

[0047] The hard monomers are acrylonitrile and isobornyl methacrylate, and the mass ratio of acrylonitrile to isobornyl methacrylate is 6:8.

[0048] Comparative Example 2 The specific implementation method of this example is the same as that of Example 1, except that, according to the weight parts, the raw materials for preparing component A include 39 parts of soft monomer, 6 parts of hard monomer, 4 parts of functional monomer, 50 parts of ethyl acetate, 0.9 parts of initiator and 0.1 parts of chain transfer agent.

[0049] The soft monomers are butyl acrylate and ethyl acrylate, and the mass ratio of butyl acrylate to ethyl acrylate is 22:17.

[0050] The hard monomer is acrylonitrile.

[0051] Comparative Example 3 The specific implementation method of this example is the same as that of Example 1, except that, by weight, the raw materials for preparing component A include 31 parts of soft monomer, 16 parts of hard monomer, 2 parts of functional monomer, 50 parts of ethyl acetate, 0.9 parts of initiator and 0.1 parts of chain transfer agent.

[0052] The soft monomers are butyl acrylate and ethyl acrylate, and the mass ratio of butyl acrylate to ethyl acrylate is 18:13.

[0053] Comparative Example 4 The specific implementation method in this example is the same as in Example 1, except that, according to the weight parts, the raw materials for preparing component A include 33 parts of soft monomer, 16 parts of hard monomer, 50 parts of ethyl acetate, 0.9 parts of initiator and 0.1 parts of chain transfer agent.

[0054] The soft monomers are butyl acrylate and ethyl acrylate, and the mass ratio of butyl acrylate to ethyl acrylate is 19:14.

[0055] Comparative Example 5 The specific implementation method in this example is the same as in Example 1, except that, according to the weight parts, the raw materials for preparing component A include 27 parts of soft monomer, 16 parts of hard monomer, 6 parts of functional monomer, 50 parts of ethyl acetate, 0.9 parts of initiator and 0.1 parts of chain transfer agent.

[0056] The soft monomers are butyl acrylate and ethyl acrylate, and the mass ratio of butyl acrylate to ethyl acrylate is 17:10.

[0057] Comparative Example 6 The specific implementation method of this example is the same as that of Example 5, except that component B is liquid epoxy resin and o-crestoaldehyde epoxy resin; the mass ratio of liquid epoxy resin to o-crestoaldehyde epoxy resin is 20:80.

[0058] Comparative Example 7 The specific implementation method of this example is the same as that of Example 5, except that component B is liquid epoxy resin and o-crestoaldehyde epoxy resin; the mass ratio of liquid epoxy resin to o-crestoaldehyde epoxy resin is 60:40.

[0059] Comparative Example 8 The specific implementation method of this example is the same as that of Example 5, except that the mass ratio of component A, component B and component C is 6:1:1.5.

[0060] Comparative Example 9 The specific implementation method in this example is the same as in Example 1, except that the mass ratio of component A, component B and component C is 9:1:1.5.

[0061] Performance testing The products prepared in each embodiment and comparative example were tested as follows: 1. Glue overflow test: Use a punching machine to punch standard holes of about 2mm in diameter in the cover film. Prepare a sample by aligning the cover film with the copper foil surface at 80℃. Then, press the cover film onto the smooth copper foil surface using a high-speed press with the following parameters: temperature 180±2℃, pressure 100kg / cm². 2 Preheat for 10 seconds, mold for 60 seconds, then use a 2D image measuring instrument to take 4 points along the circumference of the hole, measure the width of the overflow ring, and calculate the average value of each hole diameter as the final overflow amount (unit: µm). The overflow amount is represented by A, B, and C, where A is <200µm; B is 200-300µm; and C is >300µm.

[0062] 2. Peel strength test: The adhesives used in the examples and comparative examples were coated onto high-temperature resistant substrates (polyimide film, electrolytic copper, and stainless steel), respectively, and then bonded together at 80°C to form sample pieces. These samples were then pressed together using a high-speed press with the following parameters: temperature 180±2°C, pressure 100 kg / cm². 2 Preheat for 10 seconds, mold for 120 seconds, then cure at 160℃ for 1 hour. Tests are then conducted according to IPC-TM-650 to obtain peel strength data between polyimide-polyimide, between polyimide-electrolytic copper, and between polyimide-stainless steel. In the table, " / " indicates excessive adhesive overflow that cannot be measured.

[0063] 3. Reflow soldering heat resistance test: Cut the sample into a 5cm x 5cm square and bond them together at 80°C to form a sample sheet (both sides are bonded with a single-sided copper polyimide surface). Parameter settings: temperature 180±2°C, pressure 100kg / cm. 2Preheat for 10 seconds, mold for 120 seconds, then cure at 160℃ for 1 hour. Then, conduct tests according to the specifications in IPC-TM-650. During testing, observe the test pieces for any abnormal appearance such as expansion or peeling. A test piece with no abnormal appearance is rated as A, a test piece with slight expansion but no practical problems is rated as B, and a test piece with bulging or expansion is rated as C.

[0064] The test results are shown in Table 1.

[0065] Table 1

[0066] As can be seen from the data in Table 1 of the embodiments and comparative examples, the acrylate adhesive prepared in this application has excellent performance in terms of adhesive overflow, peel strength, and heat resistance compared to the comparative example. When the acrylate adhesive prepared in this application is used for bonding between polyimide films and between polyimide and stainless steel substrates, the peel strength can reach more than 17 N / cm. When used for bonding between polyimide and electrolytic copper, the peel strength can reach more than 23 N / cm. At the same time, it has excellent heat resistance for reflow soldering, meeting the high-temperature process requirements of electronic manufacturing.

Claims

1. A highly heat resistant acrylate adhesive, characterized by, The preparation raw materials of the A component, the B component and the C component; The preparation raw materials of the A component include 10-40 parts of soft monomers, 10-30 parts of hard monomers, 1-4 parts of functional monomers, 40-55 parts of ethyl acetate, 0.1-1 parts of initiator and 0.05-0.4 parts of molecular chain transfer agent, by weight; The B component is an epoxy resin composition; The C component is an organic solvent.

2. The high heat resistant acrylate adhesive according to claim 1, characterized in that, The mass ratio of the A component, the B component and the C component is (6.5-8.5):1:1.

5.

3. The high heat resistant acrylate adhesive according to claim 1, characterized in that, The soft monomers include at least one of butyl acrylate, ethyl acrylate and isooctyl acrylate.

4. The high heat resistant acrylate adhesive according to claim 1, characterized in that, The hard monomers include at least one of acrylonitrile and isobornyl methacrylate.

5. The highly heat resistant acrylate adhesive according to claim 4, characterized in that, The mass ratio of the acrylonitrile and the isobornyl methacrylate is (5-10):(10-20).

6. The high heat resistant acrylate adhesive according to claim 1, wherein, The functional monomers contain a rigid cyclic group.

7. The highly heat resistant acrylate adhesive according to claim 6, characterized in that, The functional monomers include glycidyl methacrylate.

8. The highly heat resistant acrylate adhesive according to claim 7, characterized in that, The epoxy resin composition includes liquid epoxy resin and o-cresol formaldehyde epoxy resin. 9.The high heat resistant acrylate adhesive according to claim 8, characterized in that, The mass ratio of the liquid epoxy resin and the o-cresol formaldehyde epoxy resin is (20-45):(40-65).

10. A method of preparing the high heat resistant acrylate adhesive according to any one of claims 1-9, characterized in that, The method comprises the following steps: S1, uniformly mixing and stirring the soft monomers, the hard monomers and the functional monomers to obtain a monomer mixture; S2, dissolving the initiator in ethyl acetate to obtain an initiator solution; S3, adding 1 / 3 mass of the monomer mixture and 1 / 3 mass of the initiator solution at 65℃, stirring for 1-2h, then adding the remaining monomer mixture and initiator solution, increasing the temperature to 75℃ and stirring for 2-3h, controlling the temperature at 85℃ and stirring for 3-4h, then increasing the temperature to 110℃, adding the molecular chain transfer agent and reacting for 0.5-1h to obtain the A component; S4, uniformly stirring the A component and the B component after heating to 40-50℃, cooling to room temperature, adding the C component and stirring at room temperature for 0.5-1h to obtain the high-heat-resistant acrylic adhesive.

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