Heat-resistant high-insulation UV moisture dual-curing organosilicon three-proofing adhesive and preparation method thereof

Abstract

The heat-resistant and high-insulation UV and moisture dual-curing organosilicon three-proofing adhesive has the following two aspects: firstly, the heat-resistant and high-insulation UV and moisture dual-curing organosilicon three-proofing adhesive is synthesized by phenyl siloxane, hydroxyl silicone oil and an acryloyloxy siloxane monomer, and the main chain of the organosilicon prepolymer contains a phenyl structure, a light-curable carbon-carbon double bond and a moisture-curable siloxane group; and adding a photoinitiator and a catalyst to obtain the heat-resistant and high-insulation UV and moisture dual-curing organosilicon three-proofing adhesive. According to the preparation method of the heat-resistant and high-insulation UV and moisture dual-curing organosilicon three-proofing adhesive, the heat resistance is good, the volume resistivity is high, the dielectric constant and the dielectric loss factor are high, on one hand, the heat-resistant and high-insulation UV and moisture dual-curing organosilicon three-proofing adhesive can be cured under ultraviolet irradiation, and on the other hand, the heat-resistant and high-insulation UV and moisture dual-curing organosilicon three-proofing adhesive can be cured under ultraviolet irradiation; on the other hand, due to siloxane groups, moisture curing can be well carried out in a shadow area, and finally the three-proofing adhesive with high bonding strength, high chemical corrosion resistance and excellent protection performance is formed.

Description

Technical Field

[0001] The present invention relates to the technical field of three-proof adhesives, and in particular to a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof adhesive and a preparation method thereof. Background Art

[0002] With the rapid development of the electronics industry, its application scenarios are becoming more and more extensive, and the challenges it faces are also increasing. Therefore, higher requirements are put forward for the quality of electronic products. Therefore, in electronic and electrical products, in order to resist environmental challenges (such as salt spray, humidity, aging, etc.), extend the service life of electronic products, and avoid high maintenance or replacement parts costs, a transparent protective coating is usually applied on the surface of electronic components. It is cheap in cost and reliable in performance, thus protecting the circuit board and related equipment from environmental interference and damage, such as short circuits, mildew, arcs, vibrations, corrosion, high dust, etc.

[0003] For the moisture-curing silicone three-proof adhesive layer in the traditional market, under normal circumstances, the curing takes at least several days, the curing speed is slow, and at the same time, the environmental test performance is low and the heat resistance performance is poor; for other uv-type three-proof adhesives, the shadow area is not easy to cure or can only be moisture-cured or can only be photo-cured; the adhesion of some solvent-based three-proof adhesives is not enough, and the protection performance can only meet simple protection and cannot cope with severe environmental challenges; or for other UV moisture dual-curing adhesives in the market, photo-curing and moisture can coexist, but they are not heat-resistant, and at the same time, the dielectric strength is not high (the greater the dielectric strength of a substance, the better its quality as an insulator), and the volume resistivity is difficult to reach more than 10^13 Ω·cm. Therefore, it is difficult to meet the challenges of severe usage occasions.

[0004] Therefore, it is imperative to develop a three-proof adhesive with good heat resistance, excellent insulation performance, strong reliability, and superior protection performance. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects in the prior art, and provide a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof adhesive and a preparation method thereof. This silicone three-proof adhesive has good heat resistance, strong reliability, good insulation, and superior protection performance.

[0006] To achieve the above purpose, the present invention is realized through the following two aspects:

[0007] In the first aspect, the present invention provides a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof adhesive. First, a silicone prepolymer containing a phenyl structure in the main chain, a carbon-carbon double bond capable of photo-curing, and a siloxane group capable of moisture-curing is synthesized from phenyl siloxane, hydroxyl silicone oil, and acryloxy siloxane monomer. Then, a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof adhesive can be obtained by adding a photoinitiator and a catalyst.

[0008] Preferably, the phenyl structure is located on the main chain of the silicone prepolymer, and the photocurable carbon-carbon double bond and the moisture-curable siloxane group are located on the end chain of the main chain of the silicone prepolymer.

[0009] Preferably, the phenylsiloxane is one or more of phenyltrimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, methylphenyldiethoxysilane, and diphenyldiethoxysilane.

[0010] Preferably, the hydroxy silicone oil is one within the viscosity range of 60 - 500 CPS or a combination of multiple different viscosities within the viscosity range of 60 - 500 CPS.

[0011] Preferably, the acryloxysiloxane monomer is a substance containing both silicon methoxy and acryloxy groups or a substance containing both silicon ethoxy and acryloxy groups.

[0012] Preferably, the acryloxysiloxane monomer is one or more of 3-(trimethoxysilyl)propyl methacrylate; 3-(triethoxysilyl)propyl methacrylate, 3-(methyldimethoxysilyl)propyl methacrylate; 3-(methyldiethoxysilyl)propyl methacrylate, etc.

[0013] Preferably, the photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoyl phenylphosphinate, and methyl benzoylformate.

[0014] In a second aspect, the present invention provides a preparation method of a heat-resistant and highly insulating UV-moisture dual-curable silicone three-proof coating, which is used to prepare a heat-resistant and highly insulating UV-moisture dual-curable silicone three-proof coating as described in the first aspect, and it includes the following preparation steps:

[0015] Step S1: Put 200 - 300 parts of phenylsiloxane; 200 - 300 parts of hydroxy silicone oil; 400 - 600 parts of toluene into a reaction flask, stir and keep the temperature at 40 ± 5 °C, then dropwise add 200 - 300 parts of distilled water containing 0.1 - 0.15 parts of concentrated hydrochloric acid, and control the dropping speed to finish dropping in 1 - 2 hours. After dropping, adjust the solution to 70 ± 5 °C and keep it for 2 - 4 hours;

[0016] Step S2: Then raise the temperature to 100 °C to start refluxing and distilling off the water, and raise the temperature by 10 °C every half hour; during this heating process, the solution will become transparent. When it becomes transparent, add another 200 - 300 parts of toluene until the temperature rises to 140 °C;

[0017] Step S3: Subsequently, lower the material temperature to about 40±5°C, add 100 - 150 grams of acryloyloxy siloxane monomer and 0.2 - 0.5 grams of catalyst at one time, and then raise the temperature to 70°C for heat preservation for 2 - 4 hours;

[0018] Step S4: Then raise the temperature to 130°C to start distillation. During the distillation process, on the one hand, water is distilled out, and on the other hand, the capping reaction of acryloyloxy siloxane is ensured, and distillation is carried out for 1 - 3 hours;

[0019] Step S5: Subsequently, raise the temperature to 140°C, adjust the solid content by continuously distilling the toluene solvent to ensure that the solid content is about 70%±5. Finally, cool it to room temperature and store it in the dark. Add 1 - 5% of photoinitiator and 0.01 - 0.1% of catalyst, stir and disperse to dissolve, and then discharge to obtain a heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof glue as described in the first aspect.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The present invention is prepared based on the following method: first synthesize an organosilicon prepolymer with a phenyl structure in the main chain; then introduce carbon-carbon double bonds and siloxane groups through chemical reactions on this basis, and then add a photoinitiator and a catalyst to obtain a heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof glue.

[0022] 2. A heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof glue and its preparation method provided by the present invention have the advantages of good heat resistance (still having protective performance after being tested under the condition of at least 500 hours at 85°C), high volume resistivity (greater than 8*10^14 Ω·cm), high dielectric constant and dielectric loss factor. On the one hand, it can be cured under ultraviolet light irradiation, and on the other hand, it has siloxane groups and can be well cured by moisture in the shadow area. Finally, a three-proof glue with high bonding strength, strong chemical corrosion resistance and excellent protective performance is formed. When applied in the field of circuit boards and related equipment, it can meet the higher requirements (higher heat resistance and higher insulation performance while having better three-proof performance) of this field. Specific Embodiments

[0024] Example 1:

[0025] Example 1 of the present invention provides a heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof glue. First, an organosilicon prepolymer with a phenyl structure in the main chain, photocurable carbon-carbon double bonds and moisture-curable siloxane groups is synthesized through phenyl siloxane, hydroxy silicone oil, and acryloyloxy siloxane monomer. Then, a photoinitiator and a catalyst are added to obtain a heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof glue.

[0026] Among them, the phenyl structure is located on the main chain of the silicone prepolymer, and the photocurable carbon-carbon double bond and the moisture-curable siloxane group are located on the end chain of the main chain of the silicone prepolymer.

[0027] Among them, the phenyl siloxane is derived from one or more of phenyltrimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, methylphenyldiethoxysilane, and diphenyldiethoxysilane.

[0028] Among them, the hydroxy silicone oil is one within the viscosity range of 60 - 500 CPS or a combination of multiple different viscosities within the viscosity range of 60 - 500 CPS.

[0029] Among them, the acryloxy siloxane monomer is a substance containing both silicon methoxy and acryloxy or a substance containing both silicon ethoxy and acryloxy.

[0030] More specifically, the acryloxy siloxane monomer is one or more of methacryloxypropyltrimethoxysilane; methacryloxypropyltriethoxysilane, methacryloxypropylmethyldimethoxysilane; methacryloxypropylmethyldiethoxysilane, etc.

[0031] Among them, the photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl phenylphosphonic acid ethyl ester, and methyl benzoylformate.

[0032] Among them, the catalyst is one or more of stannous octoate, dibutyltin dilaurate, and the acetylacetone chelate of dibutyltin dilaurate.

[0033] Example 2:

[0034] Example 2 of the present invention provides a preparation method of a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof adhesive,

[0035] which is used to prepare a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof adhesive as described in Example 1, and it includes the following preparation steps:

[0036] Step S1: Put 200 - 300 parts of phenyl silicone; 200 - 300 parts of hydroxyl silicone oil; 400 - 600 parts of toluene into a reaction flask, stir and keep the temperature at 40 ± 5 °C, then add dropwise 200 - 300 parts of distilled water containing 0.1 - 0.15 parts of concentrated hydrochloric acid at a rate controlled to be dropped within 1 - 2 hours. After dropping, adjust the solution to 70 ± 5 °C and keep it for 2 - 4 hours. The purpose is to ensure complete hydrolysis;

[0037] Step S2: Then raise the temperature to 100 °C to start refluxing and distilling off water, and raise the temperature by 10 °C every half hour; during this heating process, the solution will become transparent. When it becomes transparent, add another 200 - 300 parts of toluene until the temperature is raised to 140 °C;

[0038] Step S3: Subsequently, lower the material temperature to about 40 ± 5 °C, add 100 - 150 grams of acryloxy siloxane monomer and 0.2 - 0.5 grams of catalyst at one time, and raise the temperature to 70 °C and keep it for 2 - 4 hours. The purpose is to ensure the deep reaction of the acryloxy siloxane monomer;

[0039] Step S4: Then raise the temperature to 130 °C to start distillation. During the distillation process, on the one hand, water is distilled off, and on the other hand, the capping reaction of acryloxy siloxane is ensured. Distill for 1 - 3 hours;

[0040] Step S5: Subsequently, raise the temperature to 140 °C, adjust the solid content by continuously distilling the toluene solvent to ensure that the solid content is about 70% ± 5. Finally, cool to room temperature, store in the dark, add 1 - 5% of photoinitiator and 0.01 - 0.1% of catalyst, stir, disperse, dissolve and discharge to obtain a heat - resistant, highly insulating UV - moisture dual - curable silicone three - proof glue as described in Example 1.

[0041] Example 3:

[0042] Example 3 of the present invention provides experimental data of a heat - resistant, highly insulating UV - moisture dual - curable silicone three - proof glue of Example 1 prepared by the preparation method of Example 2, a single ordinary UV - moisture three - proof glue, a single commercially available three - proof glue: Dow Corning 1 - 2577, and a single market - common solvent - type acrylate three - proof glue respectively regarding adhesion test, heat resistance test, salt spray test, volume resistivity and dielectric strength test.

[0043] This experimental data has three experimental examples and three comparative examples. Among them, the components and preparation methods of Experimental Examples 1 to 3 are as follows:

[0044] Experimental Example 1: A heat - resistant, highly insulating UV - moisture dual - curable silicone three - proof glue, whose preparation steps follow the preparation method of Example 2, as follows:

[0045] Step S1: Put 200 parts of phenyltrimethoxysilane, 200 parts of 60 cps hydroxyl silicone oil, and 400 parts of toluene into a reaction flask, stir and keep the temperature at 40 ± 5 °C. Then add dropwise 200 parts of distilled water containing 0.1 part of concentrated hydrochloric acid at a rate controlled to be added dropwise within 1 - 2 hours. After adding dropwise, adjust the solution to 70 ± 5 °C and keep it warm for 2 hours. The purpose is to ensure complete hydrolysis.

[0046] Step S2: Then raise the temperature to 100 °C to start refluxing and distilling off water, and raise the temperature by 10 °C every half hour. During this heating process, the solution will become transparent. When it becomes transparent, add another 200 parts of toluene until the temperature is raised to 140 °C.

[0047] Step S3: Subsequently, lower the material temperature to about 40 ± 5 °C, add 100 grams of methacryloxypropyltrimethoxysilane and 0.2 grams of the catalyst dibutyltin dilaurate all at once, and raise the temperature to 70 °C and keep it warm for 2 hours. The purpose is to ensure the deep reaction of methacryloxypropyltrimethoxysilane.

[0048] Step S4: Raise the temperature to 130 °C to start distillation. During the distillation process, on the one hand, water is distilled off, and on the other hand, the end-capping reaction of methacryloxypropyltrimethoxysilane is ensured. Distill for 1 hour.

[0049] Step S5: Subsequently, raise the temperature to 140 °C, adjust the solid content by continuously distilling the toluene solvent to ensure that the solid content is about 70% ± 5. Finally, lower the temperature to room temperature, store it in the dark, add 1% of the photoinitiator 2-hydroxy-2-methyl-1-phenylpropanone and 0.01% of the catalyst dibutyltin dilaurate, stir, disperse, dissolve, and discharge to obtain a heat-resistant and highly insulating UV-moisture dual-curable silicone three-proof glue of Example 1.

[0050] Experimental Example 2: A heat-resistant and highly insulating UV-moisture dual-curable silicone three-proof glue, the preparation steps of which follow the preparation method of Example 2, as follows:

[0051] Step S1: Put 300 parts of phenyltriethoxysilane, 300 parts of 500 cps hydroxyl silicone oil, and 600 parts of toluene into a reaction flask, stir and keep the temperature at 40 ± 5 °C. Then add dropwise 300 parts of distilled water containing 0.15 part of concentrated hydrochloric acid at a rate controlled to be added dropwise within 1 - 2 hours. After adding dropwise, adjust the solution to 70 ± 5 °C and keep it warm for 4 hours. The purpose is to ensure complete hydrolysis.

[0052] Step S2: Then raise the temperature to 100 °C to start refluxing and distilling off water, and raise the temperature by 10 °C every half hour. During this heating process, the solution will become transparent. When it becomes transparent, add another 300 parts of toluene until the temperature is raised to 140 °C.

[0053] Step S3: Subsequently, lower the material temperature to around 40 ± 5 °C, add 150 grams of methacryloxypropyltriethoxysilane and 0.5 grams of the catalyst stannous octoate at one time, and then raise the temperature to 70 °C and keep it warm for 4 hours. The purpose is to ensure the deep reaction of methacryloxypropyltriethoxysilane;

[0054] Step S4: Then raise the temperature to 130 °C to start distillation. During the distillation process, on the one hand, water is distilled out, and on the other hand, the capping reaction of methacryloxypropyltriethoxysilane is ensured. Distill for at least 3 hours;

[0055] Step S5: Subsequently, raise the temperature to 140 °C, adjust the solid content by continuously distilling the toluene solvent to ensure that the solid content is about 70% ± 5. Finally, lower the temperature to room temperature and store it in the dark. Add 5% of the photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 0.1% of the catalyst stannous octoate, stir, disperse, dissolve, and discharge to obtain a heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof glue of Example 1.

[0056] Experimental Example 3: A heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof glue, the preparation steps of which follow the preparation method of Example 2, are as follows:

[0057] Step S1: Put 250 parts of diphenyldimethoxysilane; 250 parts of 150 cps hydroxyl silicone oil; 500 parts of toluene into a reaction flask, stir and keep it warm at 40 ± 5 °C, then dropwise add 250 parts of distilled water containing 0.12 parts of concentrated hydrochloric acid, and control the dropping speed to finish dropping in 1 - 2 hours. After dropping, adjust the solution to 70 ± 5 °C and keep it warm for 3 hours. The purpose is to ensure the complete hydrolysis;

[0058] Step S2: Then raise the temperature to 100 °C to start refluxing and distilling water, and raise the temperature by 10 °C every half hour; during this heating process, the solution will become transparent. When it becomes transparent, add another 250 parts of toluene until the temperature rises to 140 °C;

[0059] Step S3: Subsequently, lower the material temperature to around 40 ± 5 °C, add 130 grams of methacryloxypropylmethyldimethoxysilane and 0.2 grams of the catalyst stannous octoate at one time, and then raise the temperature to 70 °C and keep it warm for 3 hours. The purpose is to ensure the deep reaction of methacryloxypropylmethyldimethoxysilane;

[0060] Step S4: Then raise the temperature to 130 °C to start distillation. During the distillation process, on the one hand, water is distilled out, and on the other hand, the capping reaction of methacryloxypropylmethyldimethoxysilane is ensured. Distill for 3 hours;

[0061] Step S5: Subsequently, the temperature is further raised to 140°C, and the solid content is adjusted by continuously distilling the toluene solvent to ensure that the solid content is about 70% ± 5. Finally, 4% of the photoinitiator 1-hydroxycyclohexyl phenyl ketone and 0.05% of the catalyst dibutyltin dilaurate are added under dark storage at room temperature, stirred and dispersed until dissolved, and then discharged to obtain a heat-resistant and highly insulating UV-moisture dual-curable silicone three-proof coating of Example 1.

[0062] The three comparative examples are as follows:

[0063] Comparative Example 4 is a commercially available ordinary UV-moisture three-proof coating.

[0064] Comparative Example 5 is a commercially available three-proof coating: Dow Corning 1-2577.

[0065] Comparative Example 6 is an ordinary solvent-based acrylic three-proof coating on the market.

[0066] Among them, the composition and preparation method of the commercially available ordinary UV-moisture three-proof coating in Comparative Example 5 are as follows: 50 parts of ordinary moisture-curable polyurethane acrylate resin (containing isocyanate NCO groups); 30 parts of isobornyl acrylate; 10 parts of tetrahydrofurfuryl acrylate; 2 parts of benzoylformic acid methyl ester photoinitiator; 0.5 part of Tego 2100 leveling agent; 0.5 part of Tego 920 defoaming agent, etc. The above substances are quickly added to a blender, and the temperature is controlled at 30°C; stirred and evacuated to -0.095 Mpa; stirred in the dark at 1000 revolutions per minute for 1 hour; then nitrogen is filled to relieve pressure to obtain an ordinary UV-moisture three-proof coating.

[0067] The above six test samples of Example 3 (the six test samples refer to the test samples of Experimental Examples 1 to 3 and Comparative Examples 4 to 6) are respectively subjected to adhesion test, heat resistance test, salt spray test, volume resistivity and dielectric strength test items. Among them, the test items, methods and standards are as follows:

[0068] Adhesion test: GB / T 9286-1998.

[0069] Salt spray test: GB / T 1771-1991 Determination of resistance to neutral salt spray of paints and varnishes.

[0070] Volume resistivity (Ω.cm): GB / T1410-2006.

[0071] Dielectric strength (KV / mm): GB / T 1981.2-2009.

[0072] Heat resistance: The cured paint film is placed in a constant temperature oven at a temperature of 85 ± 5°C and a humidity of 85 ± 5 for 500 h, and the qualification or disqualification is judged by the failure of the protective performance of the glue film.

[0073] The experimental data after testing the above items are shown in Table 1:

[0074] Table 1: Test results of various types of conformal adhesives

[0075]

[0076] Therefore, it can be seen from Table 1 that

[0077] In the adhesion test item, Experimental Examples 1 to 3 are level 0, and level 0 corresponds to an "excellent" level of coating, which can meet the requirements of automotive electronics and even circuit coatings. Comparative Example 4 is level 1, and level 1 corresponds to a "good" level of coating. Comparative Examples 5 and 6 are level 2, and level 2 corresponds to a "qualified" level of coating. Comparative Examples 4 to 6 can only meet the requirements of ordinary household appliance coatings, and Comparative Examples 4-6 cannot reach the "excellent" level of coating, and thus cannot meet the requirements of circuit applications; therefore, in this item, it is proved that a heat-resistant, highly insulating, UV-moisture dual-curing silicone three-proofing adhesive of Experimental Examples 1 to 3 of this embodiment 1 has good adhesion performance, which means that it has good reliability performance and is suitable for circuit coatings.

[0078] In the heat resistance test item, Experimental Examples 1 to 3 and Comparative Example 5 passed the test, while Comparative Example 4 and Comparative Example 6 failed the test; in this item, it was proved that the heat-resistant, highly insulating, UV-moisture dual-curing silicone three-proof adhesive of Experimental Examples 1 to 3 of this embodiment 1 had good heat resistance performance.

[0079] In the salt spray test project, Experimental Examples 1 to 3 had no corrosion, peeling, cracking, or falling off, while Comparative Examples 4-6 all showed varying degrees of corrosion, peeling, cracking, and falling off and failed to pass the test; in this project, it was proved that the heat-resistant, highly insulating, UV-moisture dual-curing silicone three-proof adhesive of Experimental Examples 1 to 3 of this embodiment 1 had good salt spray resistance (corrosion resistance).

[0080] In the volume resistivity and dielectric strength test items, Experimental Examples 1 to 3 all achieved a resistivity of more than 8*10^14, with excellent insulation performance, the resistivity data of Comparative Examples 4 and 6 were relatively low and poor, and the resistivity data of Comparative Example 5 was good; at the same time, Experimental Examples 1 to 3 had high dielectric strength and good withstand voltage values, the dielectric strength data of Comparative Examples 4 and 6 were relatively low and poor, and the dielectric strength data of Comparative Example 5 was good; in this project, it is proved that the heat-resistant, high-insulation UV-moisture dual-curing silicone three-proof adhesive of Experimental Examples 1 to 3 of this embodiment 1 has good insulation performance.

[0081] In summary, among all the test items, only Experimental Examples 1-3 can maintain good heat resistance (heat resistance test item), good reliability (adhesion test item), good insulation (volume resistivity and dielectric strength test items), and good protection performance (salt spray test item).

[0082] Through the above test items, further analysis shows that the reason why Experimental Examples 1-3 can pass the above test items is as follows: after the experimental samples of Experimental Examples 1-3 are prepared, they are attached to the surface of the device to be coated (referring to the above paint film surface). First, UV rapid curing is used to initially achieve rapid positioning. Then, next, the siloxane groups of silicone can be used for further moisture curing to further improve the curing degree. Therefore, the adhesion is strong. Because phenyl groups are introduced, the bond energy is high, and at the same time, the crosslinking density is large, showing strong heat resistance.

[0083] From Comparative Example 4 and Comparative Example 6, it can be seen that the volume resistivity and dielectric strength of ordinary UV moisture-proof three-proof adhesives or acrylic three-proof adhesives are relatively low, the insulation is weak, and the heat resistance and salt spray resistance protection performance are slightly weak. Because their carbon-carbon bond energy (345 kj / mol) is smaller than the silicon-oxygen-silicon bond energy (1768 kJ / mol), the insulation of silicone is stronger.

[0084] In Comparative Example 5, it can be seen that its solvent volatility is relatively large and the odor is relatively high. In Comparative Example 5, although it is also a silicone system, the volume resistivity, dielectric strength, and salt spray test, etc. are okay, but the strength is slightly weak, manifested as slightly weak adhesion and salt spray resistance, because it only has one kind of moisture curing and the crosslinking degree is weak.

[0085] Therefore, in the above experimental data, it is proved that a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof adhesive of Embodiment 1 of the present invention has good heat resistance, strong reliability, good insulation, and excellent protection performance. Specifically, this silicone three-proof adhesive has good heat resistance (still has protection performance after being tested under the condition of at least 500 hours at 85 °C), high volume resistivity (greater than 8*10^14 Ω·cm), high dielectric constant and dielectric loss factor. On the one hand, it can be cured under ultraviolet light irradiation. On the other hand, it has siloxane groups and can be well moisture-cured in the shadow area. Finally, a three-proof adhesive with high bonding strength, strong chemical corrosion resistance, and excellent protection performance is formed. When applied in the field of circuit boards and related equipment, it can meet the higher requirements (higher heat resistance performance, higher insulation performance, and three-proof performance at the same time) of this field.

[0086] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A heat-resistant and highly insulating UV and moisture dual-curing silicone three-proof adhesive, characterized in that, First, a silicone prepolymer is synthesized from phenylsiloxane, hydroxyl silicone oil, and acryloxy siloxane monomers, with a phenyl structure in the main chain, photocurable carbon-carbon double bonds, and moisture-curable siloxane groups. Then, a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof coating can be obtained by adding a photoinitiator and a catalyst.

2. A heat-resistant and highly insulating UV moisture dual-curing silicone three-proof coating according to claim 1, wherein the phenyl structure is located on the main chain of the silicone prepolymer, and the photocurable carbon-carbon double bonds and moisture-curable siloxane groups are located on the end chains of the main chain of the silicone prepolymer.

3. A heat-resistant and highly insulating UV and moisture dual-curing silicone three-proof coating according to claim 1, characterized in that, The phenylsiloxane is one or more of phenyltrimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, methylphenyldiethoxysilane, and diphenyldiethoxysilane.

4. A heat-resistant and highly insulating UV and moisture dual-curing silicone three-proof adhesive according to claim 1, characterized in that The hydroxyl silicone oil is one within the viscosity range of 60 - 500 CPS or a combination of multiple different viscosities within the viscosity range of 60 - 500 CPS.

5. A heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof adhesive according to claim 1, characterized in that, The acryloxy siloxane monomer is a substance containing both silicon methoxy and acryloxy groups or a substance containing both silicon ethoxy and acryloxy groups.

6. A heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof adhesive according to claim 1 or 5, characterized in that, The acryloxy siloxane monomer is one or more of 3-(trimethoxysilyl)propyl methacrylate; 3-(triethoxysilyl)propyl methacrylate, 3-(methyldimethoxysilyl)propyl methacrylate; 3-(methyldiethoxysilyl)propyl methacrylate, etc.

7. A heat-resistant and highly insulating UV-moisture dual-curing silicone three-proof coating according to claim 1, characterized in that, The photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]propan-1-one, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoyl phenylphosphinate, and methyl benzoylformate.

8. A heat-resistant and highly insulating UV and moisture dual-curing silicone three-proof adhesive according to claim 1, characterized in that, The catalyst is one or more of stannous octoate, dibutyltin dilaurate, and the acetylacetone chelate of dibutyltin dilaurate.

9. A preparation method of a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof adhesive, characterized in that, It is used to prepare a heat-resistant and highly insulating UV moisture dual-curing silicone three-proof coating as described in claims 1 - 8, and it includes the following preparation steps: Step S1: Put 200 - 300 parts of phenylsiloxane; 200 - 300 parts of hydroxyl silicone oil; 400 - 600 parts of toluene into a reaction flask, stir and keep the temperature at 40 ± 5 °C, then dropwise add 200 - 300 parts of distilled water containing 0.1 - 0.15 parts of concentrated hydrochloric acid, control the dropping speed at 1 - 2 hours to finish dropping, and after dropping, adjust the solution to 70 ± 5 °C and keep it for 2 - 4 hours; Step S2: Then raise the temperature to 100 °C to start refluxing and distilling off the water, and raise the temperature by 10 °C every half hour; during this temperature-raising process, the solution will become transparent, and when it becomes transparent, add another 200 - 300 parts of toluene until the temperature is raised to 140 °C; Step S3: Subsequently, lower the material temperature to about 40 ± 5 °C, add 100 - 150 grams of acryloxy siloxane monomer and 0.2 - 0.5 grams of catalyst at one time, and raise the temperature to 70 °C and keep it for 2 - 4 hours; Step S4: Then raise the temperature to 130°C and start distillation. During the distillation process, on the one hand, water is distilled out, and on the other hand, the capping reaction of acryloyloxy siloxanyl groups is ensured. Distillation is carried out for 1 - 3 h; Step S5: Subsequently, raise the temperature to 140°C, and adjust the solid content by continuously distilling the toluene solvent to ensure that the solid content is about 70% ± 5. Finally, cool down to room temperature and store it in the dark. Add 1 - 5% of a photoinitiator and 0.01 - 0.1% of a catalyst, stir, disperse, dissolve, and discharge to obtain a heat-resistant and highly insulating UV-moisture dual-curable silicone three-proof adhesive as described in claims 1 - 7.

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