Two-component flexible epoxy potting composition as well as preparation and application thereof

Abstract

The invention discloses a two-component flexible epoxy potting composition as well as a preparation method and application thereof. According to the flexible encapsulating material obtained by the invention, the Shore A range is 60-80, the Tg range is-15 to + 10 DEG C, the cold and hot impact (-40 / 125 DEG C) is more than or equal to 200 times, and the operable time at 25 DEG C is more than or equal to 90-150 minutes. The method is suitable for integral potting and stress buffering of electronic and power supply modules such as ABS, PA, aluminum alloy, PCB and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer potting materials technology, specifically to a two-component flexible epoxy potting composition and its preparation and application. Background Technology

[0002] The main room temperature curing potting materials currently available are polyurethane, silicone, and epoxy.

[0003] Polyurethane has limited resistance to damp heat and hydrolytic stability; silicone adhesives have insufficient mechanical strength; conventional epoxy, although strong, is brittle and has a high Tg, leading to thermal shock / ABS cracking and component solder joint failure.

[0004] At the same time, the coexistence of long working time and room temperature curing is also a challenge: excessive accelerator will shorten the working time and increase the exothermic peak and generate internal stress.

[0005] Therefore, there is an urgent need for a flexible potting system that maintains the advantages of epoxy bonding and dielectric properties while possessing rubber-like Tg, low shrinkage, long working time, and resistance to heat and moisture. Summary of the Invention

[0006] In order to overcome the above-mentioned defects of the prior art, the purpose of this invention is to provide a two-component flexible epoxy potting composition and its preparation and application.

[0007] Compared with existing technologies, this invention achieves a combination of performance characteristics, including Shore A of 60–80, Tg of −15 to +10 degrees Celsius, thermal shock ≥200 cycles, and operability at 25 degrees Celsius ≥90 to 150 min, through the synergy of CTBN-epoxy grafted network, polyetheramine / amideamine / cyclic aliphatic amine ternary curing, and sheet / sphere composite filler.

[0008] A time-separation control of long workability and late-stage curing rate is achieved through urea / imidazolium salt-based curing promoters.

[0009] To achieve the objectives of this invention, the technical solution adopted is as follows: A two-component flexible epoxy potting composition comprises two parts, component A and component B, wherein the mass ratio of component A to component B is 4–1:1–1.2; Component A, by mass parts, includes the following components: 20-45 parts of bisphenol-type epoxy resin with an epoxy equivalent of 170–220 g / eq; 8–22 parts of CTBN-epoxy grafted material; 2-12 parts of reactive diluent; 12-25 parts of inorganic filler; 11-26 parts of auxiliary agents; Component B, by mass, includes the following components: 60-95 parts of amine curing agent; Curing accelerator 0.05-3 parts; 0.2-2 parts of coupling agent; Second adjuvant 0-10 parts.

[0010] In a preferred embodiment of the present invention, the bisphenol type epoxy resin with an epoxy equivalent between 170 and 220 g / eq is a bisphenol A type epoxy resin or a bisphenol F type epoxy resin with an epoxy equivalent between 170 and 220 g / eq.

[0011] In a preferred embodiment of the present invention, the CTBN solids content in the CTBN-epoxy graft is 8-14%.

[0012] In a preferred embodiment of the present invention, the CTB in the CTBN-epoxy graft has a nitrile content of 18–26 wt% and a viscosity-average molecular weight of 80–120 kJ, and the grafting mass ratio of CTBN to epoxy in the CTBN-epoxy graft is 15–35:65–85.

[0013] In a preferred embodiment of the present invention, the reactive diluent is a C12–C14 alcohol ether glycidyl ether or a polyol glycidyl ether.

[0014] In a preferred embodiment of the present invention, the inorganic filler is any one or more of the following: surface-treated flake silica, surface-treated flake talc, and alumina.

[0015] Surface-treated flake talc is preferred.

[0016] In a preferred embodiment of the present invention, the additive is any one or more of hydrophobic fumed silica, defoamer, or antioxidant.

[0017] In a preferred embodiment of the present invention, the amine curing agent is an addition mixture of polyetheramine, amide amine and cyclic aliphatic amine with an ammonia equivalent of 90–200 g / eq, and the mixing mass ratio is 30–70:20–60:0–30.

[0018] The inventors of this invention controlled the balance between low-temperature shock and moisture resistance by adjusting the amount of cyclic amine.

[0019] In a preferred embodiment of the present invention, the curing accelerator is any one or more of urea accelerators, imidazole salts, and organic acid salts.

[0020] Preferably, 0.2-1.5 parts of xylene diurea and / or 0.05-0.5 parts of imidazole quaternary ammonium salt are used. This mixture is chosen because the inventors of this invention discovered through extensive experiments that 0.2-1.5 parts of xylene diurea and / or 0.05-0.5 parts of imidazole quaternary ammonium salt allow the prepared two-component flexible epoxy potting composition to meet both the requirements of long operating time and room temperature curing start-up.

[0021] In a preferred embodiment of the present invention, the coupling agent is any one or more of aminopropyl coupling agents, epoxy coupling agents, or mercaptosilane coupling agents.

[0022] In a preferred embodiment of the present invention, the second additive is any one or more of a diluent or a rheology modifier.

[0023] In a preferred embodiment of the present invention, the second additive is a mixture of benzyl alcohol as a diluent and low-viscosity polyether as a rheology modifier, wherein the mass fraction of benzyl alcohol in the mixture is less than 8 parts.

[0024] A method for preparing a two-component flexible epoxy potting composition includes the following steps: The first step is to mix and degas the components of component A under conditions not exceeding 60 degrees Celsius and a vacuum degree ranging from -0.08 to -0.095 MPa to obtain component A; The second step is to mix the components in component B to obtain component B. The third step involves mixing component A and component B in the stated ratio, allowing them to stand at room temperature to degas, and then potting and curing them to obtain the two-component flexible epoxy potting composition.

[0025] The curing process involves curing at 25 degrees Celsius for 24-36 hours or at 60 degrees Celsius for 2-4 hours followed by leaving at room temperature until fully cured.

[0026] The equivalence ratio R of a two-component flexible epoxy potting composition is R = (total equivalent of active hydrogen in amines) / (total equivalent of epoxy) = 0.85–1.05.

[0027] A two-component flexible epoxy potting composition has an operability time of ≥90 min (100 g) at 25 degrees Celsius, a surface drying time of ≤12 h, and a complete curing time of ≤48 h.

[0028] A two-component flexible epoxy potting composition has a Shore A of 60–80, a Tg of -15 to +10 degrees Celsius, linear shrinkage of ≤1.2%, and no cracking after ≥200 cycles of thermal shock (-40 / 125 degrees Celsius, 30 min).

[0029] A two-component flexible epoxy potting composition has a mixed viscosity of 2–15 Pa·s, suitable for self-leveling potting, and its thermal conductivity can be adjusted to 0.3–1.0 W·m⁻¹·K⁻¹ by using alumina / boron nitride.

[0030] An application of a two-component flexible epoxy potting composition, said application being used in integral potting and stress buffering of electronic / power modules, LED drivers, energy storage BMS, sensors, and ABS / PA housings.

[0031] The beneficial effects of this invention are as follows: The present invention provides a flexible potting material with a Shore A range of 60–80, a Tg range of -15 to +10 degrees Celsius, a thermal shock resistance (-40 / 125 degrees Celsius) of ≥200 times, and an operability time of ≥90–150 min at 25 degrees Celsius.

[0032] Suitable for overall potting and stress buffering of electronic and power modules made of ABS, PA, aluminum alloy, PCB and other materials. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, in the following descriptions, well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of the invention.

[0035]

[0036] In the above embodiments, the mixing ratio of component A to component B is 2:1.

[0037] The preparation method involves drying the inorganic filler at 110-130 degrees Celsius before use.

[0038] The first step is to mix and degas the components of component A under conditions of 45-55 degrees Celsius and a vacuum degree range of -0.08 to -0.095 MPa to obtain component A; The second step is to mix the components in component B to obtain component B. The third step involves mixing component A and component B in a 2:1 ratio, allowing them to stand at room temperature for 3-8 minutes to degas, and then potting and curing to obtain a two-component flexible epoxy potting composition.

[0039] In the example, the potting process involves lining an aluminum foil bag / barrel with nitrogen sealing.

[0040] Curing at room temperature: 25 °C for 24–36 h; or accelerated: 60 °C for 3 h + 25 °C and allowed to stand until fully cured (≤48 h).

[0041] Compared with the prior art, the Shore A≈70, Tg≈-6 degrees Celsius, and thermal shock (-40 / 125 degrees Celsius, 30 min cycle) of Embodiment 1 of the present invention are ≥200 times.

[0042] In Example 2 of the present invention, Shore A≈62, Tg≈-12 degrees Celsius, and thermal shock (-40 / 125 degrees Celsius, 30min cycle) ≥200 times.

[0043] Comparative Example 1 (no CTBN, Shore A≈85, Tg≈+18 °C, approximately 50 thermal shocks).

[0044] The composition prepared in this invention has the following characteristics: mixed viscosity (25 °C, 10 s⁻¹): 3–8 Pa·s; working time: 90–150 min; shrinkage ≤1.2%; dielectric constant (1 kHz): 2.9–3.4; volume resistivity ≥10¹³ Ω·cm; and exhibits no cracking after 1000 h of exposure to humid conditions at 85 °C / 85%RH. (See details below.) Figure 1 .

[0045] The foregoing has shown and described the basic principles and main features of the invention and the advantages of the invention.

[0046] Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A two-component flexible epoxy potting composition, comprising component A and component B, characterized in that, The mass ratio of component A to component B is 4–1:1–1.2; Component A, by mass parts, includes the following components: 20-45 parts of bisphenol-type epoxy resin with an epoxy equivalent of 170–220 g / eq; 8–22 parts of CTBN-epoxy grafted material; 2-12 parts of reactive diluent; 12-25 parts of inorganic filler; 11-26 parts of auxiliary agents; Component B, by mass, includes the following components: 60-95 parts of amine curing agent; Curing accelerator 0.05-3 parts; 0.2-2 parts of coupling agent; Second adjuvant 0-10 parts.

2. The two-component flexible epoxy potting composition as described in claim 1, comprising component A and component B, characterized in that, The bisphenol type epoxy resin with an epoxy equivalent between 170 and 220 g / eq is either bisphenol A type epoxy resin or bisphenol F type epoxy resin with an epoxy equivalent between 170 and 220 g / eq.

3. The two-component flexible epoxy potting composition as described in claim 1, comprising component A and component B, characterized in that, The CTBN solids content in the CTBN-epoxy graft is 8-14%; The CTB in the CTBN-epoxy graft has a nitrile content of 18–26 wt% and a viscosity-average molecular weight of 80–120 kJ, and the grafting mass ratio of CTBN to epoxy in the CTBN-epoxy graft is 15–35:65–85.

4. The two-component flexible epoxy potting composition as described in claim 1, comprising component A and component B, characterized in that, The reactive diluent is a C12–C14 alcohol ether glycidyl ether or a polyol glycidyl ether. The inorganic filler is any one or more of the following: surface-treated flake silica, surface-treated flake talc, and alumina. In a preferred embodiment of the present invention, the additive is any one or more of hydrophobic fumed silica, defoamer, or antioxidant.

5. A two-component flexible epoxy potting composition as described in claim 1, comprising component A and component B, characterized in that, The amine curing agent is an addition mixture of polyether amine, amide amine and cyclic aliphatic amine with an ammonia equivalent of 90–200 g / eq, in a mixing mass ratio of 30–70:20–60:0–30. The curing accelerator is any one or more of urea accelerators, imidazole salts, and organic acid salts.

6. A two-component flexible epoxy potting composition as described in claim 1, comprising component A and component B, characterized in that, The coupling agent is any one or more of aminopropyl coupling agents, epoxy coupling agents, or mercaptosilane coupling agents; The second additive is any one or more of a diluent or a rheology modifier.

7. A method for preparing a two-component flexible epoxy potting composition according to any one of claims 1-6, comprising the following steps: The first step is to mix and degas the components of component A under conditions not exceeding 60 degrees Celsius and a vacuum degree ranging from -0.08 to -0.095 MPa to obtain component A; The second step is to mix the components in component B to obtain component B. The third step involves mixing component A and component B in the specified ratio, allowing them to stand at room temperature to degas, and then potting and curing them to obtain the two-component flexible epoxy potting composition. The curing process involves curing at 25 degrees Celsius for 24-36 hours or at 60 degrees Celsius for 2-4 hours followed by leaving at room temperature until fully cured.

8. The application of a two-component flexible epoxy potting composition as described in any one of claims 1-6, characterized in that, The applications are in the overall potting and stress buffering of electronic / power modules, LED drivers, energy storage BMS, sensors, and ABS / PA housings.

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