One-component potting glue suitable for automobile radar and preparation method thereof

Abstract

The present invention discloses a one-component potting adhesive suitable for automotive radar and a preparation method thereof, comprising the following components by mass: 35-55 parts of heat-resistant resin, 35-40 parts of curing agent, 13-20 parts of flame retardant, 3-5 parts of chitosan rubber, and 1-2 parts of accelerator. The present invention also proposes a one-component potting adhesive suitable for automotive radar and a preparation method thereof. The one-component potting adhesive suitable for automotive radar described in the present invention has excellent flame retardancy and thermal conductivity, easy curing conditions, operability at room temperature, low thermal expansion coefficient, and high insulation and mechanical properties. The one-component potting adhesive described in the present invention has passed the cold and hot shock cycle test and double 85 test from 50°C to 125°C, which is a significant improvement over the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of epoxy potting adhesives, and in particular relates to a single-component high-efficiency potting adhesive used in automotive radars and a preparation method thereof. Background Art

[0002] Potting is the process of mechanically or manually injecting liquid potting glue into devices equipped with electronic components and PCB circuits, and solidifying it into thermosetting polymer insulating material at room temperature or under heating, so as to achieve the purposes of bonding, sealing, potting and coating protection; it can enhance the integrity and insulation of electronic devices, avoid direct exposure of components and circuits, and has waterproof, dustproof and moisture-proof properties.

[0003] The car radar sensor transmits signals through the induction coil. When it encounters an obstacle, there will be an echo signal. The sensor processes the received echo signal through the host to determine the location of the obstacle and warn the driver that there is an obstacle ahead, making driving safer. The induction coil is encapsulated in a narrow cavity, with a metal coil wrapped inside the cavity, and connected to the coil inside the cavity through two metal wires. Since the metal coil will generate current and electromagnetic induction inside the cavity, an insulating environment is required inside. Therefore, the encapsulated induction coil component needs to be potted with glue to make it a whole, so as to improve its resistance to external impact and vibration; at the same time, it also avoids direct exposure of the coil and improves the waterproof, dustproof and moisture-proof performance of the overall device.

[0004] my country's automobile industry is in a stage of rapid development, and automobile configurations are gradually improving, including radar sensors, which account for a relatively high proportion. Therefore, there is a higher demand for the development of potting technology for radar sensor components. Because it is to pot a small cavity containing a coil and prevent the coil from falling off the cavity, the potting material must have high insulation properties, mechanical properties and low thermal expansion coefficient; at the same time, it must also take into account flame retardancy, moisture resistance and low viscosity, so as to ensure the reliability of the sensor. Patent No. CN1150288804A discloses a semiconductor potting glue whose specific synthesis method is complex and has high curing conditions, and has high production requirements.

[0005] Therefore, it is necessary to provide a car radar sensor potting glue with strong insulation and flame retardancy, low viscosity, moisture resistance and aging resistance. Summary of the invention

[0006] The technical problems to be solved by the present invention are: overcoming the problem that the thermal expansion coefficient is too large, which makes it easy to burst or fall off when the temperature rises, resulting in the coil being unable to be tightly bonded to the shell; overcoming the problem that the viscosity is high and the process cannot be efficiently potted; overcoming the low shear force and improving the resistance of the packaged device to external impact.

[0007] In order to solve the above technical problems, the present invention proposes the following technical solutions:

[0008] A one-component potting adhesive suitable for automotive radar, comprising a heat-resistant resin, a curing agent, a flame retardant, a chitosan rubber, and an accelerator, wherein the weight proportions of the heat-resistant resin, the curing agent, the flame retardant, the chitosan rubber, and the accelerator are as follows:

[0009]

[0010] As a further solution of the present invention, the heat-resistant resin selected for the potting glue is one or more of the multifunctional epoxy resins AFG-90, EPM-420, and AG-80, preferably EPM-420.

[0011] As a further solution of the present invention, the shell polymer rubber particles selected for the potting glue are one or two of XP-425 and EPX-125, preferably XP-425.

[0012] As a further solution of the present invention, the flame retardant selected for the potting glue is one or both of aluminum hydroxide and magnesium hydroxide, preferably aluminum hydroxide.

[0013] As a further solution of the present invention, the curing agent selected for the potting glue is an acid anhydride curing agent, preferably methylhexahydrophthalic anhydride.

[0014] As a further solution of the present invention, the accelerator used in the potting glue is a modified imidazole accelerator, preferably 2101CN-liquid imidazole as the accelerator.

[0015] The present invention also provides a method for preparing a one-component potting adhesive suitable for automotive radar, which is characterized by comprising the following steps:

[0016] Step 1: Weigh 35-55 parts of heat-resistant resin, 35-40 parts of curing agent, 13-20 parts of flame retardant, 3-5 parts of chitosan rubber, and 1-2 parts of accelerator according to mass parts;

[0017] Step 2: Place the heat-resistant resin and the shell polymer rubber particles into a mixer and stir them in a vacuum for 15 minutes at a speed of 250 rpm;

[0018] Step 3: Add the flame retardant to the composite material obtained in step 2 and stir for 30 minutes at a speed of 500 rpm under vacuum;

[0019] Step 4: freeze the compound prepared in step 3 at low temperature to 10°C-15°C, add the curing agent to the frozen compound, and stir at 250 rpm in a vacuum for 15 minutes;

[0020] Step 5: Freeze the mixed compound prepared in step 4 at a temperature of 10°C-15°C, add the accelerator to the frozen compound and stir it at a speed of 500 rpm for 30 minutes in a vacuum;

[0021] Step 6: The mixture stirred in step 5 is cryogenically frozen to obtain a single-component potting adhesive suitable for automotive radar.

[0022] The present invention has the following beneficial effects:

[0023] 1. The one-component potting glue suitable for automotive radar described in the present invention has low viscosity, good fluidity and high potting efficiency.

[0024] 2. The one-component potting glue for automobile radar described in the present invention is filled with chitosan rubber particles, which can improve the mechanical and thermal stability of the potting glue of the present invention.

[0025] 3. The present invention provides a one-component potting adhesive suitable for automotive radar, which uses a heat-resistant resin and a flame retardant and can pass the UL94V-0 flame retardancy test and a -50°C to 125°C impact 10 cycle test. DETAILED DESCRIPTION

[0026] The present invention proposes a one-component high thermal conductivity adhesive, which aims to solve the following problems: the thermal expansion coefficient is too large, and it is easy to burst or fall off when the temperature rises, resulting in the problem that the coil cannot be tightly bonded to the shell; the viscosity is high, and it is not possible to efficiently perform potting in the process; the shear force is small, and it cannot guarantee the overall resistance to external force impact, etc.

[0027] The following technical solutions are proposed for the above problems: a one-component potting adhesive suitable for automotive radar and a preparation method thereof. The overall idea is as follows:

[0028] Step 1: Weigh 35-55 parts of heat-resistant resin, 35-40 parts of curing agent, 13-20 parts of flame retardant, 3-5 parts of chitosan rubber, and 1-2 parts of accelerator according to mass parts;

[0029] Step 2: Place the heat-resistant resin and the shell polymer rubber particles into a mixer and stir them in a vacuum for 15 minutes at a speed of 250 rpm;

[0030] Step 3: Add the flame retardant to the composite material obtained in step 2 and stir for 30 minutes at a speed of 500 rpm under vacuum;

[0031] Step 4: freeze the compound prepared in step 3 at low temperature to 10°C-15°C, add the curing agent to the frozen compound, and stir at 250 rpm in a vacuum for 15 minutes;

[0032] Step 5: Freeze the mixed compound prepared in step 4 at a temperature of 10°C-15°C, add the accelerator to the frozen compound and stir it at a speed of 500 rpm for 30 minutes in a vacuum;

[0033] Step 6: Freeze the mixture after stirring in step 5 to obtain a one-component potting glue suitable for automotive radar.

[0034] In order to better understand the above technical solution, the above technical solution will be described in detail below in combination with Table 1-1 and Table 1-2 of the specification and a specific implementation plan.

[0035] Example 1

[0036] The potting glue formula in the embodiment of the present invention is 35 parts of heat-resistant resin, preferably EPM-420, 38 parts of curing agent, preferably methyl hexahydrophthalic anhydride, 20 parts of flame retardant, preferably aluminum hydroxide, 5 parts of shell polymer rubber particles, preferably XP-425, 2 parts of accelerator, preferably 2101CN-liquid modified imidazole; operation steps: the heat-resistant resin EPM-420 and the shell polymer rubber particles XP-425 are stirred at a speed of 250rpm in a vacuum for 15 minutes, and then the flame retardant aluminum hydroxide is added in a vacuum at a speed of 500rpm and stirred for 30 minutes, and then the stirred composite is frozen at a low temperature to 10°C and the curing agent methyl hexahydrophthalic anhydride is added, and the speed is 250rpm in a vacuum and stirred for 15 minutes. After stirring, the accelerator 2101CN-liquid modified imidazole is added after cooling to 12°C, and the speed is 500rpm in a vacuum. Stir for 30 minutes, and then cool at a low temperature to obtain the potting glue of the first embodiment of the present invention.

[0037] Example 2

[0038] The potting glue formula in the embodiment of the present invention is 40 parts of heat-resistant resin, preferably EPM-420, 37 parts of curing agent, preferably methyl hexahydrophthalic anhydride, 16 parts of flame retardant, preferably aluminum hydroxide, 5 parts of chitosan rubber particles, preferably XP-425, 2 parts of accelerator, preferably 2101CN-liquid modified imidazole; the operation steps are consistent with Example 1.

[0039] Example 3

[0040] The potting glue formula in the embodiment of the present invention is 45 parts of heat-resistant resin, preferably EPM-420, 35 parts of curing agent, preferably methyl hexahydrophthalic anhydride, 15 parts of flame retardant, preferably aluminum hydroxide, 4 parts of chitosan rubber particles, preferably XP-425, 1 part of accelerator, preferably 2101CN-liquid modified imidazole; the operation steps are consistent with Example 1.

[0041] Example 4

[0042] The potting glue formula in the embodiment of the present invention is 55 parts of heat-resistant resin, preferably EPM-420, 28 parts of curing agent, preferably methyl hexahydrophthalic anhydride, 13 parts of flame retardant, preferably aluminum hydroxide, 3 parts of chitosan rubber particles, preferably XP-425, 1 part of accelerator, preferably 2101CN-liquid modified imidazole; the operating steps are consistent with Example 1.

[0043] Comparative Example 1

[0044] The difference between the potting compound formula in the comparative example of the present invention and that in Example 2 is that AFG-90 is used as the heat-resistant resin, EPX-125 is used as the chitosan rubber, and magnesium hydroxide is used as the flame retardant; the remaining parts by mass and steps are the same as those in Example 2.

[0045] Comparative Example 2

[0046] The difference between the potting glue formula in the embodiment of the present invention and the comparative example 1 is that AG-80 is selected as the heat-resistant resin; the remaining parts by mass and steps are the same as those in the comparative example 2.

[0047] Each group of formulations of Examples 1-4 and Comparative Examples 1-2 is shown in Table 1-1, and the corresponding properties of each group of formulations of Examples 1-4 and Comparative Examples 1-2 are shown in Table 1-2, wherein the viscosity test method is: using a U.S. Brookfield HBDV-2T viscometer, take 200 ml of the test sample under a standard environment of 25°C, place the probe in the test sample, and read the data after the data stabilizes; the thermal expansion coefficient test is tested using the ASTM E831-14 standard, the temperature is -40°C to 280°C, the unit is μm / (m·°C); the hardness standard is ISO 868 shore D 200°C for 4 hours; the shear strength test adopts the ISO 4857 standard, steel frosted surface; the hot and cold shock temperature range is -50°C to 125°C; the volume resistivity is tested using the IEC 60093 standard; the curing condition temperature is 100°C and the thickness is 3mm.

[0048] Table 1-1:

[0049] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Heat resistant resin 35 40 45 55 40 40 Curing agent 38 37 35 28 37 37 Flame retardants 20 16 15 13 16 16 Chitosan 5 5 4 3 5 5 Accelerator 2 2 1 1 2 2

[0050] (Note: The proportions of each component in the table are in parts by mass)

[0051] Table 1-2:

[0052]

[0053] (Note: The above example data is available from the laboratory)

[0054] The technical solution in the above-mentioned embodiment of the present invention has the following technical effects:

[0055] 1. Low viscosity, convenient for potting, which can increase the potting efficiency by 15% during production;

[0056] 2. Short curing time: It can be fully cured in as fast as 22 minutes at 100℃ and 3mm thickness, which effectively shortens the subsequent packaging time and improves the overall production efficiency;

[0057] 3. Withstands 10 cycles of thermal shock and a flame retardancy rating of UL94V-0, which can effectively ensure the stability and reliability of potted devices.

Claims

1. A one-component potting compound suitable for automotive radar, comprising a heat-resistant resin, a curing agent, a flame retardant, a chitosan rubber, and an accelerator, characterized in that: The heat-resistant resin, curing agent, flame retardant, shell polymer rubber, and accelerator are as follows in parts by weight: The heat-resistant resin is one or more of the multifunctional epoxy resins AFG-90, EPM-420, and AG-80, the shell polymer rubber particles are one or two of XP-425 and EPX-125, the flame retardant is one or two of aluminum hydroxide and magnesium hydroxide, the curing agent is an acid anhydride curing agent, and the accelerator is a modified imidazole accelerator.

2. The one-component potting adhesive suitable for automotive radar according to claim 1, characterized in that The preparation method of the one-component potting glue comprises the following steps: Step 1: Weigh 35-55 parts of heat-resistant resin, 35-40 parts of curing agent, 13-20 parts of flame retardant, 3-5 parts of chitosan rubber, and 1-2 parts of accelerator according to mass parts; Step 2: Place the heat-resistant resin and the shell polymer rubber particles into a mixer and stir them in a vacuum for 15 minutes at a speed of 250 rpm; Step 3: Add the flame retardant to the composite material obtained in step 2 and stir for 30 minutes at a speed of 500 rpm under vacuum; Step 4: freeze the compound prepared in step 3 at low temperature to 10°C-15°C, add the curing agent to the frozen compound, and stir at 250 rpm in a vacuum for 15 minutes; Step 5: Freeze the mixed compound prepared in step 4 at a temperature of 10°C-15°C, add the accelerator to the frozen compound and stir it at a speed of 500 rpm for 30 minutes in a vacuum; Step 6: The mixture stirred in step 5 is cryogenically frozen to obtain a single-component potting adhesive suitable for automotive radar.

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