Addition type potting adhesive primer, preparation method and application thereof

Abstract

The application belongs to the technical field of silicone addition type heat-conducting flame-retardant pouring sealant, and particularly discloses an addition type pouring sealant primer, a preparation method and application thereof. According to weight parts, the addition type pouring sealant primer comprises 50-70 parts of tackifier, 0.5-4 parts of crosslinking agent, 0.001-0.1 parts of catalyst and 30-50 parts of solvent; the tackifier is a functional titanate tackifier modified by a titanate; the functional titanate tackifier modified by a titanate is prepared by an ester exchange reaction of trimethylolpropane diallyl ether, ethyl acetoacetate and a mono-alkoxy type titanate. The addition type pouring sealant can improve the adhesion of components in a driving power supply, prevent water vapor or moisture in the air from penetrating into the electronic device through the combined surface of the material and the glue layer, and is beneficial to improving the waterproof and moisture-proof performance of the LED driving power supply when used outdoors.

Description

Technical Field

[0001] This invention relates to the field of silicone addition-type thermally conductive and flame-retardant potting compound technology, specifically to an addition-type potting compound primer, its preparation method, and its application. Background Technology

[0002] Organosilicon addition-type thermally conductive and flame-retardant potting compound has good resistance to high and low temperatures, ozone and weathering. No by-products are generated during the vulcanization process, and the shrinkage rate is low. After curing, the product has stable electrical and chemical properties and excellent moisture resistance. It is widely used in lighting, electrical appliances, new energy and other fields.

[0003] In recent years, with the rapid development and promotion of the LED industry, addition-cure silicone thermally conductive and flame-retardant potting compounds have become the mainstream potting products for LED driver power supplies. However, after the silicone addition-cure potting compounds are cured, the surface of the product is mostly non-polar groups with low surface energy, resulting in poor adhesion to materials inside the driver power supply. This leads to easy peeling between the adhesive layer and the substrate (such as aluminum shell materials, PET insulating sheets, PVC insulating tape, PCB boards, etc.). Moisture or humidity in the air can easily penetrate into the electronic device through the interface between the material and the adhesive layer, affecting the product's insulation and corrosion resistance. Especially when LED driver power supplies are used outdoors, stricter waterproof and moisture-proof performance is required, and the potting compound must have good adhesion to various components inside the power supply. To improve the adhesion between addition-cure potting compounds and internal components of LED drivers, one approach is to directly add tackifiers to the potting compound. However, this method does not significantly improve adhesion and is costly. Most tackifiers contain amino compounds, which can inhibit the catalytic activity of Pt in the potting compound, affecting the curing effect of the addition-cure potting compound. Another approach is to use a primer to assist in improving the adhesion between the potting compound and the substrate. This method is currently the most effective and cost-effective. Summary of the Invention

[0004] In view of the above-mentioned shortcomings, this invention provides an addition-cure potting compound primer, its preparation method, and its application. This invention provides a novel addition-cure potting compound primer that assists in bonding the addition-cure potting compound to the substrate of internal components in an LED driver power supply. The primer has good spreadability, a suitable drying time, and after drying, forms a uniform coating film on the surface of the substrate inside the LED power supply. It is compatible with the addition-cure potting compound, does not cause poisoning, and helps maintain good adhesion between the potting compound and the substrate of the internal components. The addition-cure potting compound of this invention prevents moisture or humidity from easily penetrating into the electronic device through the interface between the material and the adhesive layer, thus improving the waterproof and moisture-proof performance of the LED driver power supply when used outdoors.

[0005] To achieve the above objectives, the present invention provides an addition-type potting compound primer, comprising, by weight: 50-70 parts of tackifier, 0.5-4 parts of crosslinking agent, 0.001-0.1 parts of catalyst, and 30-50 parts of solvent;

[0006] The tackifier is a functional titanate ester tackifier modified with titanate ester;

[0007] The modified functional titanate tackifier is prepared by transesterification of trimethylolpropane diallyl ether, ethyl acetoacetate, and monoalkoxy titanate.

[0008] According to one aspect of the present invention, the preparation method of the titanate-modified functional titanate tackifier includes the following steps:

[0009] Place monoalkoxy titanate into a reaction vessel, purge with nitrogen for protection, and start stirring. Heat to 60-70℃, and slowly add trimethylolpropane diallyl ether dropwise, completing the addition within 2-3 hours. Heat to 80-85℃ and maintain the reaction temperature for 3 hours. Then, apply vacuum distillation, maintaining the pressure below -0.09 MPa, and heat to 85-120℃ to distill off excess alcohols and other byproducts from the titanate ester exchange. After 0.5 hours of reaction completion, purge with nitrogen again, cool to 60-70℃, and slowly add ethyl acetoacetate dropwise, completing the addition within 1.5-2 hours. Heat to 80-85℃ and react for 2 hours. Then, apply vacuum distillation, maintaining the pressure below -0.09 MPa, and heat to 85-120℃ to distill off excess alcohols and other byproducts. After cooling to room temperature with nitrogen, add solvent and seal for storage.

[0010] Preferably, the inert atmosphere includes either nitrogen or argon.

[0011] According to one aspect of the present invention, the monoalkoxy titanate comprises one or both of tetraisopropyl titanate and tetraisobutyl titanate; the effective content of the trimethylolpropane diallyl ether is greater than 98%; and the effective content of the ethyl acetoacetate is greater than 98%.

[0012] According to one aspect of the present invention, the crosslinking agent is polymethylsiloxane, and the viscosity of the polymethylsiloxane at 25°C is 10-100 CP.

[0013] According to one aspect of the invention, the catalyst is a Pt catalyst.

[0014] According to one aspect of the invention, the solvent includes at least one selected from toluene, xylene, and petroleum ether.

[0015] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned addition-curing potting compound primer, comprising the following steps:

[0016] Under an inert atmosphere, the tackifier is stirred, refluxed, and heated to 40°C; a catalyst is added, followed by a slow addition of a crosslinking agent, and the temperature is raised to 60-70°C. The mixture is reacted for 1 hour and then cooled to room temperature; a solvent is added, the mixture is stirred until homogeneous, and the product is discharged to obtain an addition-type potting compound primer.

[0017] Preferably, the inert atmosphere includes either nitrogen or argon.

[0018] Based on the same inventive concept, the present invention also provides the application of the above-mentioned addition-cure potting compound primer or the addition-cure potting compound primer prepared by the above preparation method in the internal potting of LED driver power supplies.

[0019] The beneficial effects of this invention are:

[0020] (1) This invention uses trimethylolpropane diallyl ether, ethyl acetoacetate, and titanate as the main raw materials. Through transesterification, functional groups ether bonds and ester bonds are introduced into the titanate. After the reaction, a functional titanate tackifier is synthesized. The tackifier molecule contains not only ester groups but also double ether bond groups, which work together to form a high polarity. The prepared primer has good air-drying properties and can improve the surface polarity of the substrate during application. At the same time, the reactive group ethylene bond introduced into the tackifier, along with the addition of crosslinking agent polymethylsiloxane, Pt catalyst, and solvent, a new addition-type potting compound primer is prepared under certain conditions.

[0021] (2) The addition-type potting compound primer of the present invention uses trimethylolpropane diallyl ether, ethyl acetoacetate and titanate as the main raw materials. It is a functional tackifier synthesized first through transesterification reaction, and then a certain amount of crosslinking agent, catalyst, etc. are added. The addition-type primer prepared under certain conditions can solve the problem of poor adhesion or debonding between the substrate of the internal device of the LED driver power supply and the addition-type potting compound. It has excellent adhesion to the aluminum shell of the LED power supply, PCB board, PET insulating sheet and PVC insulating tape. It will not debonding or corrosion after 1000 hours in a high temperature and high humidity environment of 85°C.

[0022] (3) The addition-type potting compound primer of the present invention improves the adhesion of the addition-type potting compound to various components inside the power supply (such as aluminum shell, PET insulating sheet, PVC insulating tape, PCB board, etc.), and prevents moisture or humidity in the air from easily penetrating into the electronic device through the interface between the material and the adhesive layer, which is beneficial to improving the waterproof and moisture-proof performance of the LED power supply when used outdoors. Attached Figure Description

[0023] Figure 1The adhesion between the addition-type potting compound primer prepared in Example 1 of this invention and the substrate after aging for 1000 hours at 85% RH and 85°C: (a) Substrate is aluminum shell; (b) Substrate is PET insulating sheet; (c) Substrate is PVC insulating tape; (d) Substrate is PCB board.

[0024] Figure 2 The following are examples of the adhesion between the addition-type potting compound primer prepared in Comparative Example 1 of this invention and the substrate: (a) The substrate is an aluminum shell; (b) The substrate is a PET insulating sheet; (c) The substrate is a PVC insulating tape; (d) The substrate is a PCB board. Detailed Implementation

[0025] To make the present invention easier to understand, specific embodiments are described below to further illustrate the invention. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical terms used below have the same meaning as understood by those skilled in the art; unless otherwise specified, the raw materials and reagents involved herein can be purchased commercially or prepared by known methods.

[0026] Example 1

[0027] An addition-type potting compound primer and its preparation method:

[0028] An addition-type potting compound primer, comprising the following raw materials in parts by weight:

[0029] Functional titanate ester modified titanate tackifier: 60 parts

[0030] Polymethylsiloxane: 1.5 parts (50 CP, 25°C)

[0031] Pt catalyst: 0.02 parts

[0032] Xylene: 40 parts

[0033] The preparation method of the above-mentioned titanate-modified functional titanate tackifier includes the following steps:

[0034] Place 100 parts of tetraisopropyl titanate into a reaction vessel, purge with nitrogen for protection, start stirring, heat to 65°C, and slowly add 80 parts of trimethylolpropane diallyl ether dropwise, controlling the addition to be completed within 2 hours. Heat to 85°C, maintain the reaction temperature for 3 hours, then vacuum distill, controlling the pressure below -0.09 MPa, heat to 110°C, react for 0.5 hours, purge with nitrogen again, cool to 65°C, and slowly add up to 50 parts of ethyl acetoacetate dropwise, controlling the addition to be completed within 1.5 hours. Heat to 85°C, react for 2 hours, then vacuum distill, controlling the pressure below -0.09 MPa, heat to 90°C, and after distillation is complete, purge with nitrogen to cool to room temperature. After completion, add 40 parts of xylene, stir evenly, and seal for storage.

[0035] A method for preparing an addition-type potting compound primer includes the following steps:

[0036] Take 60 parts of the self-made thickener, purge with nitrogen for protection, start stirring, reflux, heat to 40°C, add 0.02 parts of Pt catalyst, then slowly add 1.5 parts of polymethylsiloxane, heat to 60°C after completion, react for 1 hour, cool to room temperature, add 45 parts of xylene, stir evenly, discharge, and prepare the above-mentioned primer.

[0037] Example 2

[0038] An addition-type potting compound primer and its preparation method:

[0039] An addition-type potting compound primer, comprising the following raw materials in parts by weight:

[0040] Functional titanate ester modified titanate tackifier: 55 parts

[0041] Polymethylsiloxane: 2 parts (50 CP, 25°C)

[0042] Pt catalyst: 0.02 parts

[0043] Xylene: 45 parts

[0044] The preparation method of the above-mentioned titanate-modified functional titanate tackifier includes the following steps:

[0045] Place 100 parts of tetrabutyl titanate into a reaction vessel, purge with nitrogen for protection, start stirring, heat to 65°C, and slowly add 75 parts of trimethylolpropane diallyl ether dropwise over 2 hours. Heat to 85°C and maintain the reaction temperature for 3 hours. Then, vacuum distillation is carried out, maintaining the pressure below -0.09 MPa. Heat to 110°C and react for 0.5 hours. Purge with nitrogen again, cool to 65°C, and slowly add 55 parts of ethyl acetoacetate dropwise over 1.5 hours. Heat to 85°C and react for 2 hours. Then, vacuum distillation is carried out, maintaining the pressure below -0.09 MPa. Heat to 100°C and wait for distillation to complete. Purge with nitrogen to cool to room temperature. After completion, add 50 parts of xylene, stir well, and seal for storage.

[0046] A method for preparing an addition-type potting compound primer includes the following steps:

[0047] Take 55 parts of the self-made thickener, purge with nitrogen for protection, start stirring, reflux, heat to 40°C, add 0.02 parts of Pt catalyst, then slowly add 2 parts of polymethylsiloxane, after completion, heat to 60°C, react for 1 hour, cool to room temperature, add 45 parts of xylene, stir evenly, discharge, and prepare the above-mentioned primer.

[0048] Comparative Example 1

[0049] Place 100 parts of tetraisopropyl titanate into a reaction vessel, purge with nitrogen for protection, start stirring, heat to 65°C, and slowly add 50 parts of ethyl acetoacetate dropwise, controlling the addition to be completed within 1.5 hours. Heat to 85°C, react for 2 hours, then vacuum distill under reduced pressure, controlling the pressure below -0.09 MPa, heat to 90°C, and wait for distillation to complete. Purge with nitrogen to cool to room temperature. After completion, add 75 parts of trimethylolpropane diallyl ether and 40 parts of xylene, stir evenly, and seal for storage.

[0050] The other components and preparation methods are the same as in Example 1.

[0051] Comparative Example 2

[0052] The components and preparation method are the same as in Example 1, but no trimethylolpropane diallyl ether is used in the entire preparation process.

[0053] Comparative Example 3

[0054] Place 100 parts of tetraisopropyl titanate into a reaction vessel, purge with nitrogen for protection, start stirring, heat to 65°C, slowly add 80 parts of trimethylolpropane diallyl ether, controlling the addition to be completed within 2 hours, heat to 85°C, maintain the temperature for 3 hours, then vacuum distill, controlling the pressure below -0.09 MPa, heat to 110°C, react for 0.5 hours, purge with nitrogen again, and then lower the temperature to room temperature. After completion, add 55 parts of ethyl acetoacetate and 40 parts of xylene, stir evenly, and seal for storage.

[0055] Comparative Example 4

[0056] Without any primer, a blank control of the addition-curing potting compound for LED power supplies from well-known brands on the market.

[0057] Performance testing and results analysis

[0058] The drying time and adhesion of the addition-type primers provided in Examples 1-2 and Comparative Examples 1-4 were tested.

[0059] Testing Procedure: The product was tested using a well-known brand of addition-curing potting compound specifically designed for LED power supplies. The technical parameters of this product are as follows: (Thermal conductivity: 0.9 W / m·K; Mixing ratio: 1:1; Viscosity after mixing: 3000 CP-4500 CP; Curing time: 30-40 min working time, fully cured in 24 h; Tensile strength at 25℃: 0.6 MPa; Elongation: 50%).

[0060] Test items:

[0061] Drying time: Visually, under the conditions of 23±2℃ and 50±5%RH, the prepared primer liquid was applied to the substrate surface by spraying. A uniform coating film was formed on the substrate surface within 24 hours after drying, and the time was recorded.

[0062] Adhesion test to substrate: Appendix D, 1.2, Hand pull test method of GB / T 16776-2005;

[0063] ○ Print: Silicone gel fracture (agglomeration and destruction rate 50%-100%);

[0064] △Print: Some of the silicone gel layer and the substrate have peeled off at the interface (agglomeration damage rate 1% to 50%).

[0065] ×print: No adhesion (agglomeration and destruction rate 0%).

[0066] High temperature and high humidity environment: Storage conditions 85%RH, 85℃, 1000h.

[0067] The test results are shown in Table 1 below:

[0068] Table 1. Overall performance test results of Examples 1-2 and Comparative Examples 1-4

[0069]

[0070] As shown in Table 1, Examples 1-2, the drying times of the addition-type primer prepared by transesterification of functional tackifiers synthesized from trimethylolpropane diallyl ether, ethyl acetoacetate, and titanate as main raw materials were 5 min and 7 min, respectively. When sprayed onto LED aluminum housings, PET insulating sheets, PVC insulating tape, and PCB boards, the addition-type potting compound exhibited good adhesion to each substrate. This is because the functional additives in the prepared primer introduced ether bonds and polar ester groups, which have good compatibility with the substrate and improve adhesion. Furthermore, under double 85 conditions, after 1000 hours of aging, the addition-type potting compound still maintained stable adhesion. Specifically, as shown... Figure 1 As shown, by Figure 1 It can be seen that under the double 85 conditions, after 1000 hours of aging, the addition-type potting compound did not exhibit corrosion. This is because the synthesized functional tackifier also contains vinyl double bonds. During the preparation of the primer, under the action of the Pt catalyst, the crosslinking agent polymethylsiloxane undergoes an addition reaction with the silane-hydrogen bonds. The resulting compound contains active Si-H bonds, which undergo an addition crosslinking reaction with the ethylene silicone oil in the potting compound to form a stable crosslinked network structure.

[0071] As shown in Table 1, during the preparation of the primer, when trimethylolpropane diallyl ether does not directly participate in the reaction or is not added to the raw materials, compared with the results of Example 1, the drying time of Comparative Example 1 was 360 min, and the drying time of Comparative Example 2 was still an oily liquid after 24 h. When spraying LED housing aluminum, PET insulating sheet, PVC insulating tape, and PCB board substrate, the additive potting compound of Comparative Examples 1, 2, and the blank sample Comparative Example 4 detached from each substrate in blocks, with no adhesive residue. Figure 2 As shown, trimethylolpropane diallyl ether exhibits good air-drying properties in the transesterification reaction of titanate, which can shorten the drying time of the primer and improve the adhesion of the functional titanate tackifier to various substrates. In Comparative Example 3, when ethyl acetoacetate does not participate in the transesterification reaction of the functional titanate tackifier, it is directly added to the primer. The drying time after primer spraying is 8 minutes. The potting compound shows some adhesion to various substrates, including LED aluminum shells, PET insulating sheets, PVC insulating tape, and PCB boards. However, the adhesion effect is still different from that of Example 1. This indicates that the synergistic effect of ethyl acetoacetate on adhesion to various substrates is reduced when it does not participate in the transesterification reaction. This is because ethyl acetoacetate is volatile and easily hydrolyzed, leading to the deactivation and failure of the polar ester groups in the primer, directly affecting the adhesion between the potting compound and the substrate.

[0072] Therefore, in summary, a functional ether and ester bond group is introduced into titanate esters via transesterification to synthesize a functional titanate ester tackifier. This tackifier's molecular structure contains not only ester groups but also dual ether bond groups, which synergistically exhibit high polarity. During application, it can improve the surface polarity of the substrate. The prepared primer has good air-drying properties and adhesive-aiding effects. When sprayed onto aluminum LED power supply casings, PCB boards, PET insulating sheets, and PVC insulating adhesives, the addition-cure potting compound exhibits excellent adhesion to each substrate and does not show debonding or corrosion after 1000 hours in a high-temperature and high-humidity environment (85°C).

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An addition-type potting compound primer, characterized in that, Based on parts by weight, it consists of the following substances: 50-70 parts of tackifier, 0.5-4 parts of crosslinking agent, 0.001-0.1 parts of catalyst, and 30-50 parts of solvent; The tackifier is a functional titanate ester tackifier modified with titanate ester; The titanate-modified functional titanate tackifier is prepared by transesterification of trimethylolpropane diallyl ether, ethyl acetoacetate, and titanate; the titanate is one or both of tetraisopropyl titanate and tetraisobutyl titanate; the preparation method of the titanate-modified functional titanate tackifier includes the following steps: Place the titanate ester into a reaction vessel, purge with nitrogen for protection, and start stirring. Heat to 60-70℃, and slowly add trimethylolpropane diallyl ether dropwise, completing the addition within 2-3 hours. Heat to 80-85℃ and maintain the reaction temperature for 3 hours. Then, apply vacuum distillation, controlling the pressure below -0.09 MPa, and heat to 85-120℃ to distill off excess alcohols and other byproducts from the titanate ester exchange. After 0.5 hours of reaction completion, purge with nitrogen again, cool to 60-70℃, and slowly add ethyl acetoacetate dropwise, completing the addition within 1.5-2 hours. Heat to 80-85℃ and react for 2 hours. Then, apply vacuum distillation, controlling the pressure below -0.09 MPa, and heat to 85-120℃ to distill off excess alcohols and other byproducts. After cooling to room temperature with nitrogen, add solvent and seal for storage.

2. The addition-curing potting compound primer according to claim 1, characterized in that, The crosslinking agent is polymethylsiloxane, and the viscosity of the polymethylsiloxane at 25°C is 10-100 CP.

3. The addition-curing potting compound primer according to claim 1, characterized in that, The catalyst is a Pt catalyst.

4. The addition-curing potting compound primer according to claim 1, characterized in that, The solvent includes at least one of toluene, xylene, and petroleum ether.

5. The method for preparing the addition-curing potting compound primer according to any one of claims 1 to 4, characterized in that, Includes the following steps: Under an inert atmosphere, the tackifier is stirred, refluxed, and heated to 40°C; a catalyst is added, followed by a slow addition of a crosslinking agent, and the temperature is raised to 60-70°C. The mixture is reacted for 1 hour and then cooled to room temperature; a solvent is added, the mixture is stirred until homogeneous, and the product is discharged to obtain an addition-type potting compound primer.

6. The application of the addition-type potting compound primer according to any one of claims 1 to 4 or the addition-type potting compound primer prepared by the preparation method according to claim 5 in the internal potting of LED driver power supplies.

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