A bio-based modified epoxy resin insulating adhesive and its preparation method

Abstract

The present invention relates to the technical field of polymer materials, and particularly relates to a bio-based modified epoxy resin insulating adhesive and a preparation method thereof. The components included in the bio-based modified epoxy insulating adhesive are: an epoxy resin composition, a coupling agent, a curing agent, and an inorganic filler; the epoxy resin composition includes bisphenol A type epoxy resin and bio-based modified epoxy resin. The bio-modified epoxy resin insulating adhesive provided by the present invention has good high temperature resistance, corrosion resistance, peel strength, and heat shock resistance. At the same time, the surface modification of the inorganic filler by the coupling agent promotes its better compatibility in the resin, improving the electrical insulation performance, dielectric performance, and mechanical properties of the modified epoxy insulating adhesive.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a bio-based modified epoxy resin insulating adhesive and a preparation method thereof. Background Art

[0002] Epoxy resin insulating adhesives have excellent bonding properties, electrical insulation properties, chemical corrosion resistance properties, low curing shrinkage rate, etc., and are widely used in the field of copper clad laminate manufacturing. The main function of the insulating adhesive is to prevent short circuits between copper layers or with the surrounding environment and provide insulation protection.

[0003] Currently, the technologies for using insulating adhesives in copper clad laminates mainly include the following aspects:

[0004] 1. Polymer materials: Common insulating adhesive materials include polyurethane, epoxy resin, benzaldehyde resin, phenolic resin, etc. These materials have good insulation properties and bonding properties and can effectively isolate the conductive parts.

[0005] 2. Coating process: During the manufacturing process, the insulating adhesive is evenly coated on the surface of the copper layer through coating technology to form a uniform insulating film. Common coating methods include spraying, roll coating, printing, etc.

[0006] 3. Thermal curing: Most insulating adhesives need to be thermally cured at a certain temperature to ensure their adhesion and stability on the circuit board. Common curing temperatures range from 100°C to 200°C, which are specifically determined according to the insulating adhesive materials used.

[0007] 4. Bonding process: After coating and curing, a firm bond is formed between the insulating adhesive and the copper layer. This bonding process can effectively improve the insulation performance of the circuit board and can withstand a certain amount of mechanical stress.

[0008] The insulating adhesive affects the electrical properties, mechanical strength, and heat resistance of the copper clad laminate, and plays an important role in improving the stability, reliability, and durability of the circuit board. With the continuous progress of technology, the research and development of insulating adhesive materials and processes are also continuously carried out to meet the manufacturing requirements of electronic products with different needs.

[0009] The focus of the research of the present invention is to introduce bio-groups into the epoxy resin molecules to change the cross-linked structure after resin curing, improve the resin insulation performance, mechanical properties, dielectric properties, etc., so as to meet the continuously developing technical requirements of electronic products. Summary of the Invention

[0010] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a bio-based modified epoxy resin insulating adhesive with excellent electrical insulation performance, high temperature resistance, good mechanical properties, and excellent dielectric properties, and a preparation method thereof.

[0011] To achieve the above object, the present invention discloses the following technical solutions:

[0012] The first aspect of the present invention discloses a bio-based modified epoxy resin insulating adhesive, comprising the following components in parts by mass:

[0013]

[0014] The epoxy resin composition includes bisphenol A type epoxy resin and bio-based modified epoxy resin, and the mass ratio of the bisphenol A type epoxy resin to the bio-based modified epoxy resin is 1:(0.2 - 0.3);

[0015] The coupling agent is at least one of methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane;

[0016] The bio-based modified epoxy resin is linolenic acid modified epoxy resin, and the preparation method of the linolenic acid modified epoxy resin includes the following steps:

[0017] (1) Mix bisphenol F type epoxy resin, linolenic acid, and a solvent to obtain mixture A;

[0018] (2) Under an anaerobic environment, add the catalyst tetrabutylammonium bromide to mixture A and stir to react;

[0019] (3) Remove the solvent to obtain linolenic acid modified epoxy resin.

[0020] Linolenic acid is an unsaturated fatty acid with many carbon-carbon double bond structures. Introducing linolenic acid groups into bisphenol F epoxy increases the content of carbon-carbon double bonds. During the resin curing process, a higher content of double bonds promotes the oxidative polymerization reaction, increases the resin curing rate, generates more crosslinking sites, forms a denser three-dimensional crosslinked network structure, increases the crosslinking density, and improves the mechanical properties of the overall resin system such as the peel strength. However, too high a crosslinking density will cause excessive internal stress, resulting in poor crack resistance and heat shock resistance of the resin. Therefore, the addition amounts of bisphenol A type epoxy resin and linolenic acid modified epoxy are preferably the mass ratios of the present invention, and good high-temperature resistance, corrosion resistance, peel strength, and heat shock resistance are achieved under this ratio.

[0021] Preferably, the bisphenol A type epoxy resin is selected from at least one of E-51, E-44, and E-20.

[0022] Preferably, the mass parts of each raw material added in the preparation method of the linolenic acid modified epoxy resin are as follows:

[0023] Bisphenol F type epoxy resin 40 - 45 parts;

[0024] Linolenic acid 15 - 20 parts;

[0025] 0.5 - 0.6 parts of tetrabutylammonium bromide.

[0026] Preferably, in step (2) of the preparation method of the linolenic acid modified epoxy resin, the reaction temperature is 100 - 120 °C, and the reaction ends when the acid value of the reaction product ≤ 7 mgKOH / g. Under this preferred condition, the esterification degree can reach more than 95%.

[0027] Preferably, the bisphenol f type epoxy resin is selected from at least one of F - 51 and F - 44.

[0028] Preferably, the solvent is selected from at least one of propylene glycol monobutyl ether, propylene glycol monophenyl ether, ethylene glycol monomethyl ether, and ethylene glycol monobutyl ether.

[0029] Preferably, the curing agent is selected from at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, and diethylaminopropylamine.

[0030] Preferably, the inorganic filler includes silica powder and titanium dioxide powder, and the mass ratio of the silica powder to the titanium dioxide powder is 1:(0.3 - 0.5);

[0031] The particle size D50 of the silica powder ≤ 2.8 μm, and the particle size D100 ≤ 10 μm;

[0032] The particle size D50 of the titanium dioxide powder ≤ 2 μm, the particle size D100 ≤ 6 μm, and the density is 2 - 4 g / cm 3 .

[0033] Both silica powder and titanium dioxide powder are non - polar inorganic materials with low polarizability and conductivity. Under their synergistic action, the charge accumulation and current leakage in the resin can be reduced, and the volume resistivity and surface resistivity can be lowered; meanwhile, the dielectric constants of silica powder and titanium dioxide powder are close to that of air, and the overall density of the resin system can be directly reduced by physical filling to lower the dielectric constant and dielectric loss of the resin, thereby improving the insulation strength and breakdown voltage resistance of the resin.

[0034] Silica powder and titanium dioxide powder have high melting points and thermal stabilities, and can resist the thermal decomposition and oxidation of the insulating glue at high temperatures; meanwhile, the compatibility of silica powder and titanium dioxide powder with the resin system is improved through surface modification with coupling agents, thereby improving the heat resistance, weather resistance, and anti - aging properties of the resin, and prolonging the insulation life of the resin.

[0035] In the present invention, the microscopic sizes of the silica powder and the titanium dioxide powder can effectively disperse the two uniformly in the resin system, avoiding agglomeration and sedimentation phenomena; they can reduce the internal cohesive force between epoxy glue molecules, increase the adhesive force, and improve the bonding performance of the resin; due to the small particle size of the inorganic filler, more resin glue will be adsorbed on its surface, and under the action of the coupling agent, it will be tightly combined with the resin molecules. When added to a certain amount, an ideal bonding interface is formed, thereby improving the peel strength of the entire resin system; while an excessive amount of inorganic filler will affect the adhesive force of the resin, resulting in a decrease in its peel strength and shear strength.

[0036] Preferably, it further includes a diluent, and the mass fraction of the diluent is 30 - 40 parts;

[0037] The diluent is at least one of methyl ethyl ketone, acetone, toluene, xylene, and ethyl acetate.

[0038] The second aspect of the present invention provides a preparation method of the aforementioned bio-based modified epoxy resin insulating glue, including the following steps:

[0039] (1) Weigh the raw materials according to the formula amount;

[0040] (2) Dissolve the inorganic filler and the coupling agent in the diluent, and stir to obtain mixture ①;

[0041] (3) Heat the epoxy resin composition to 50 - 70 °C, add mixture ① and the curing agent thereto, and stir to obtain the bio-based modified epoxy resin insulating glue.

[0042] The beneficial effects of the present invention:

[0043] The modified epoxy resin insulating glue provided by the present invention has good high-temperature resistance, corrosion resistance, anti-peel strength, and heat shock resistance. At the same time, the surface modification of the inorganic filler by the coupling agent promotes its better compatibility in the resin, improving the electrical insulation performance, dielectric performance, and mechanical properties of the modified epoxy insulating glue. Description of the Drawings

[0044] Figure 1 is the general chemical structure formula of bisphenol F-type epoxy resin;

[0045] Figure 2 is the chemical structural formula of linolenic acid;

[0046] Figure 3 is the general chemical structure formula of linolenic acid-modified bisphenol F-type epoxy resin. Detailed Embodiments

[0047] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0048] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0049] In the present invention:

[0050] The silica powder is ultrafine silica with a particle size D50 ≤ 2.8 μm and a particle size D100 ≤ 10 μm, purchased from Xinxi Metallurgical Chemical Industry;

[0051] The titanium dioxide has a particle size D50 ≤ 2 μm, a particle size D100 ≤ 6 μm, and a density of 2 - 4 g / cm 3 , and is purchased from Xinxi Metallurgical Chemical Industry;

[0052] Other raw materials used in the examples and comparative examples are all commercially available.

[0053] Preparation of bio - based modified epoxy resin

[0054] Step (1): Mix bisphenol f - type epoxy resin (as shown in Figure 1 ), linolenic acid (as shown in Figure 2 ) and a solvent to obtain mixture A;

[0055] Step (2): Under nitrogen protection, heat to 100 - 120 °C, add the catalyst tetrabutylammonium bromide to mixture A, stir and react, and end the reaction when the acid value reaches ≤ 7 mgKOH / g;

[0056] Step (3): Remove the solvent to obtain linolenic acid - modified epoxy resin (as shown in Figure 3 ).

[0057] Table 1 Raw material components of bio - based modified epoxy resin

[0058]

[0059] Note: “——” in the table indicates no addition.

[0060] Preparation of examples and comparative examples

[0061] Step (1): Weigh the raw materials according to Table 2 and Table 3;

[0062] Step (2): Add the inorganic filler to the diluent dissolved with the coupling agent, and uniformly mix by ultrasonic stirring to obtain mixture ①;

[0063] Step (3): Heat the epoxy resin composition to 50 - 70 °C, add the mixture ① and the curing agent thereto, and stir evenly to obtain the insulating adhesives for the examples and comparative examples.

[0064] Table 2 Raw material components of the examples

[0065]

[0066]

[0067] Note: “——” in the table indicates no addition.

[0068] Table 3 Raw material components of the comparative examples

[0069]

[0070] Note: “——” in the table indicates no addition.

[0071] Preparation of the copper clad laminates for the examples and comparative examples

[0072] Immerse the glass fiber cloth in the insulating adhesives (examples and comparative examples) for 20 min, dry it at 190 °C for 5 min to obtain the pre-cured sheet; cover the pre-cured sheet with copper foil, and hot press it at 230 °C for 30 min, then cut it into shape to obtain the copper clad laminates for the examples and comparative examples.

[0073] Performance testing

[0074] Perform performance testing on the copper clad laminates prepared in Examples 1 - 4 and Comparative Examples 1 - 4;

[0075] The test items are as follows:

[0076] CTI value: Test according to the standard method of 《IEC-112》;

[0077] Peel strength: Test according to the test standard of 《IPC-TM-650》2018;

[0078] Glass transition temperature: Test according to the test standard of 《IPC-TM-650》2018;

[0079] Dielectric constant and dielectric loss: Test according to the specification of 《ASTM D150》;

[0080] Volume resistivity test: Test according to GB / T 1410-2006; After regularizing the sample into a circular sheet, the test voltage is 40 V;

[0081] The obtained results are shown in Table 4;

[0082] Table 4 Performance test results

[0083]

[0084] Result analysis:

[0085] It can be seen from comparing Example 4 with Comparative Example 1 that the modified bisphenol F-type epoxy has the effects of improving the heat shock resistance, high temperature resistance and peel strength of the resin system;

[0086] It can be seen from comparing Example 4 with Comparative Examples 2 and 3 that the preferred raw material addition ratio of the present invention can effectively improve the high temperature resistance, insulation performance and mechanical properties of the resin insulating glue;

[0087] It can be seen from comparing Example 4 with Comparative Example 4 that the synergistic effect of titanium dioxide powder and silicon dioxide powder has the effect of improving the electrical properties of the resin insulating glue.

[0088] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A bio-based modified epoxy resin insulating adhesive, characterized in that, Comprising the following components in parts by mass: The epoxy resin composition includes bisphenol A type epoxy resin and bio-based modified epoxy resin, and the mass ratio of the bisphenol A type epoxy resin to the bio-based modified epoxy resin is 1:(0.2 - 0.3); The bisphenol A type epoxy resin is selected from at least one of E-51, E-44, and E-20; The coupling agent is at least one of methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane; The bio-based modified epoxy resin is linolenic acid modified epoxy resin, and the preparation method of the linolenic acid modified epoxy resin includes the following steps: (1) Mix bisphenol F type epoxy resin, linolenic acid, and a solvent to obtain mixture A; (2) Under an anaerobic environment, add the catalyst tetrabutylammonium bromide to mixture A and stir to react; (3) Remove the solvent to obtain linolenic acid modified epoxy resin; The mass parts of each raw material added in the preparation method of the linolenic acid modified epoxy resin: Bisphenol F type epoxy resin 40 - 45 parts; Linolenic acid 15 - 20 parts; Tetrabutylammonium bromide 0.5 - 0.6 part; In step (2) of the preparation method of the linolenic acid modified epoxy resin, the reaction temperature is 100 - 120 °C, and the reaction ends when the acid value of the reaction product ≤ 7 mgKOH / g; The bisphenol F type epoxy resin is selected from at least one of F-51 and F-44; The inorganic filler includes silica powder and titanium dioxide powder, and the mass ratio of the silica powder to the titanium dioxide powder is 1:(0.3 - 0.5); The particle size D50 of the silica powder ≤ 2.8 μm, and the particle size D100 ≤ 10 μm; The particle size D50 of the titanium dioxide is ≤ 2 μm, the particle size D100 is ≤ 6 μm, and the density is 2 - 4 g / cm 3 .

2. The bio-based modified epoxy resin insulating adhesive according to claim 1, characterized in that The solvent is selected from at least one of propylene glycol butyl ether, propylene glycol phenyl ether, ethylene glycol monomethyl ether, and ethylene glycol butyl ether.

3. The bio-based modified epoxy resin insulating adhesive according to claim 1, characterized in that, The curing agent is at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, and diethylaminopropylamine.

4. The bio-based modified epoxy resin insulating adhesive according to claim 1, wherein It also includes a diluent, and the mass part of the diluent is 30 - 40 parts; The diluent is at least one of methyl ethyl ketone, acetone, toluene, xylene, and ethyl acetate.

5. The preparation method of the bio-based modified epoxy resin insulating adhesive according to any one of claims 1-4, characterized in that, Including the following steps: (1) Weigh the raw materials according to the formula amount; (2) Dissolve the inorganic filler and the coupling agent in the diluent and stir to obtain mixture ①; (3) Heat the epoxy resin composition to 50 - 70 °C, add mixture ① and the curing agent thereto, and stir to obtain the bio-based modified epoxy resin insulating glue.

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