A kind of organic silicone adhesive and its preparation method and application

Abstract

The present invention discloses an organic silicone adhesive and a preparation method and application thereof. The organic silicone adhesive comprises a component A and a component B; the component A comprises a double-terminal vinyl polysiloxane, aluminum hydroxide, and a silane coupling agent; the component B comprises a double-terminal vinyl polysiloxane, a double-terminal hydrogen-containing polysiloxane, a side hydrogen-containing polysiloxane, aluminum hydroxide, and a silane coupling agent; the conductivity of the aluminum hydroxide is less than or equal to 30 μS / m; and the tackifier is selected from triallyl isocyanurate grafted with epoxy groups and methoxy groups. The present invention utilizes a specific tackifier, combines a double-terminal vinyl polysiloxane, a double-terminal hydrogen-containing polysiloxane, and a side hydrogen-containing polysiloxane, and simultaneously uses aluminum hydroxide with relatively low conductivity. The prepared organic silicone adhesive has the advantages of excellent fluidity, high thermal conductivity, high flame retardancy, and good voltage resistance, and has good bonding properties to substrates such as PCB and aluminum, and can meet the requirements of high-voltage power supplies for waterproofing, moisture-proofing, insulation, and heat dissipation.

Description

Technical Field

[0001] The invention belongs to the technical field of organic materials, and in particular relates to an organic silicone adhesive and a preparation method and application thereof. Background Art

[0002] In some special industrial application scenarios, such as high-voltage test equipment, power transmission and distribution systems, medical imaging equipment and other fields, high-voltage power supplies play a key role. As a packaging and protection material for high-voltage power supplies, high-voltage power supply potting glue has good insulation and high-voltage resistance. At the same time, as the power of the power supply increases, the thermal conductivity requirements of the potting glue are further increased. Silicone potting glue has excellent high and low temperature resistance. After being filled and modified with thermal conductive fillers, it has good heat dissipation and high-voltage resistance.

[0003] In addition to good thermal conductivity, bubble removal, and high voltage resistance, the potting glue of the high-voltage power supply should also have excellent adhesion to the PCB board or the shell. If the potting glue and the PCB are not effectively bonded, a gap may be generated between the glue and the PCB under high and low temperature of the power supply or other aging conditions, so that the two high-voltage components of the high-voltage power supply may break through the air, causing power supply abnormalities; therefore, the potting glue will greatly improve the safety of the high-voltage power supply after increasing adhesion.

[0004] The thermal conductive fillers of silicone potting glue mainly include alumina, silicon powder, aluminum hydroxide, boron nitride, etc. There are many patent documents on improving the thermal conductivity of silicone potting glue; however, there are relatively few documents on how to prepare high thermal conductivity and high voltage resistance. The prior art mentions that aluminum hydroxide can be used as a thermal conductive filler, and the prepared potting glue has good initial voltage resistance, but after being soaked in water for a period of time, its voltage resistance decreases significantly; others mention that silane coupling agents can be used to modify the surface of aluminum hydroxide to improve the overall voltage resistance of the glue, but it still cannot meet the requirements of high thermal conductivity and high voltage resistance. Summary of the invention

[0005] In order to overcome at least one of the problems existing in the above-mentioned prior art, one of the objectives of the present invention is to provide an organic silicone adhesive.

[0006] A second object of the present invention is to provide a method for preparing the above-mentioned organic silicone adhesive.

[0007] A third object of the present invention is to provide an application of the above-mentioned organic silicone adhesive.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] The first aspect of the present invention provides an organic silicone adhesive, comprising a component A and a component B; the component A comprises the following raw materials: a first double-terminal vinyl polysiloxane, a first aluminum hydroxide, a first silane coupling agent, and a catalyst; the component B comprises the following raw materials: a second double-terminal vinyl polysiloxane, a double-terminal hydrogen-containing polysiloxane, a side hydrogen-containing polysiloxane, a second aluminum hydroxide, a second silane coupling agent, an inhibitor, and a tackifier;

[0010] The electrical conductivity of the first aluminum hydroxide and the electrical conductivity of the second aluminum hydroxide are each independently less than or equal to 30 μS / m;

[0011] The adhesion promoter is selected from triallyl isocyanurate grafted with epoxy and methoxy groups.

[0012] In the present invention, the first double-terminal vinyl polysiloxane is the same as or different from the second double-terminal vinyl polysiloxane; the first aluminum hydroxide is the same as or different from the second aluminum hydroxide; the first silane coupling agent is the same as or different from the second silane coupling agent.

[0013] Preferably, the electrical conductivity of the first aluminum hydroxide and the electrical conductivity of the second aluminum hydroxide are each independently less than or equal to 20 μS / m.

[0014] Preferably, the particle size of the first aluminum hydroxide and the particle size of the second aluminum hydroxide are each independently 1 to 15 μm.

[0015] Preferably, the first aluminum hydroxide and the second aluminum hydroxide each independently include first particles and second particles, the particle size of the first particles is 1 to 5 μm, and the particle size of the second particles is 5 to 15 μm; further preferably, the particle size of the first particles is 1 to 3 μm, and the particle size of the second particles is 8 to 12 μm.

[0016] Preferably, the first aluminum hydroxide and the second aluminum hydroxide each independently include first particles and second particles, the electrical conductivity of the first particles is less than or equal to 5 μS / m, and the electrical conductivity of the second particles is less than or equal to 20 μS / m.

[0017] In the present invention, the double-terminal vinyl polysiloxane, the double-terminal hydrogen-containing polysiloxane and the side hydrogen-containing polysiloxane contain small molecular organic silicon ring bodies, such as D3 (hexamethylcyclotrisiloxane), D4 (octamethylcyclotetrasiloxane), D5 (decamethylcyclopentasiloxane), D6 (dodecamethylcyclohexasiloxane), D7 (tetradecamethylcycloheptasiloxane), D8 (hexadecylcyclooctasiloxane), D9 (octadecylcyclononasiloxane) and D10 (icosylcyclodecasiloxane). The total content of D3 to D10 refers to the sum of the masses of the above-mentioned small molecular organic silicon ring bodies.

[0018] Preferably, the total content of small molecule organosilicon ring bodies D3-D10 of the first double-ended vinyl polysiloxane and the total content of small molecule organosilicon ring bodies D3-D10 of the second double-ended vinyl polysiloxane are each independently less than or equal to 500 ppm; further independently less than or equal to 300 ppm; more preferably 10-300 ppm.

[0019] Preferably, the viscosity of the first dual-end vinyl polysiloxane at 25° C. and the viscosity of the second dual-end vinyl polysiloxane at 25° C. are each independently 50 to 5000 mPa·s; and are further preferably each independently 100 to 500 mPa·s.

[0020] Preferably, the vinyl content of the first dual-end vinyl polysiloxane and the vinyl content of the second dual-end vinyl polysiloxane are each independently 0.2 to 2 wt %; further preferably, each independently 0.3 to 1.2 wt %.

[0021] Preferably, the chemical formulas of the first dual-end vinyl polysiloxane and the second dual-end vinyl polysiloxane are independently represented by the following formula (IV): In formula (IV), D is 10-500.

[0022] In the present invention, in formula (IV), D is an integer.

[0023] Preferably, the total content of the small molecule organosilicon ring bodies D3 to D10 of the double-terminal hydrogen-containing polysiloxane is less than or equal to 500 ppm; more preferably less than or equal to 300 ppm; and even more preferably 10 to 300 ppm.

[0024] Preferably, the viscosity of the dual-terminal hydrogen-containing polysiloxane at 25° C. is 10 to 1000 mPa·s; more preferably, it is 100 to 600 mPa·s.

[0025] Preferably, the hydrogen content of the double-terminal hydrogen-containing polysiloxane is 0.01 to 0.18 wt %, and more preferably 0.015 to 0.05 wt %.

[0026] Preferably, the chemical formula of the double-terminal hydrogen-containing polysiloxane is as shown in the following formula (VI): Formula (V); In formula (V), D is 20 to 300.

[0027] In the present invention, in formula (V), D is an integer.

[0028] Preferably, the total content of the small molecule organosilicon ring bodies D3 to D10 of the side hydrogen-containing polysiloxane is less than or equal to 500 ppm; more preferably less than or equal to 300 ppm; and even more preferably 10 to 300 ppm.

[0029] Preferably, the viscosity of the side hydrogen-containing polysiloxane at 25° C. is 40 to 200 mPa·s; more preferably, it is 40 to 110 mPa·s.

[0030] Preferably, the hydrogen content of the side hydrogen-containing polysiloxane is 0.08-0.3 wt %.

[0031] Preferably, the chemical formula of the side hydrogen-containing polysiloxane is as shown in the following formula (VI):

[0032] In formula (VI), D is 20-80, and D' is 5-10.

[0033] In the present invention, in formula (VI), D and D' are both integers.

[0034] Preferably, the catalyst is selected from a platinum catalyst; further preferably, the platinum catalyst includes at least one of a divinyltetramethyldisiloxane platinum complex, a divinyloctamethyltetrasiloxane platinum complex or a chloroplatinic acid alcohol solution.

[0035] Preferably, the inhibitor comprises at least one of acetylene cyclohexanol, methyl butynol, tetramethyl divinyl disiloxane or trimethyl-dodecyl alcohol; further preferably, the inhibitor comprises at least one of acetylene cyclohexanol, methyl butynol or trimethyl-dodecyl alcohol.

[0036] Adding inhibitors to the adhesive can control its reaction speed during curing, making it have excellent operability during glue pouring.

[0037] Preferably, the first silane coupling agent and the second silane coupling agent independently include a methoxy mono-terminated silane coupling agent, an ethoxy mono-terminated silane coupling agent or a combination thereof; further preferably, the silane coupling agent is selected from a methoxy mono-terminated silane coupling agent.

[0038] Preferably, the chemical formula of the first silane coupling agent and the chemical formula of the second silane coupling agent are independently represented by the following formula (VII): In formula (VII), R1 is a C1-C5 alkyl group; R2 is a C1-C5 alkyl group; x is 1-12; n is 10-60; and m is 1-3.

[0039] In the present invention, in formula (VII), x, n and m are all integers.

[0040] Preferably, in formula (VII), R1 is methyl or ethyl; further preferably, in formula (VII), R1 is methyl.

[0041] Preferably, in formula (VII), R2 is methyl or ethyl; further preferably, in formula (VII), R2 is methyl.

[0042] Preferably, the tackifier comprises a compound of formula (I) and / or a compound of formula (II);

[0043]

[0044] Preferably, the tackifier comprises a compound of formula (I) and a compound of formula (II).

[0045] Preferably, in the tackifier, the mass ratio of the compound of formula (I) to the compound of formula (II) is 1:(0.1-0.6); more preferably 1:(0.15-0.5); and even more preferably 1:(0.2-0.4).

[0046] Preferably, the tackifier further comprises a compound of formula (III);

[0047] Preferably, in the tackifier, the mass ratio of the compound of formula (I) to the compound of formula (III) is 1:(0.4-0.9); more preferably 1:(0.5-0.8); and even more preferably 1:(0.6-0.7).

[0048] In some specific embodiments of the present invention, the tackifier is prepared by a preparation method comprising the following steps: performing an addition reaction on diallyl monoglycidyl isocyanurate and trimethoxysilane to obtain the tackifier.

[0049] Preferably, in the preparation method of the tackifier, the mass ratio of diallyl monoglycidyl isocyanurate to trimethoxysilane is 1:(0.2-0.4); more preferably, it is 1:(0.25-0.35).

[0050] Preferably, in the method for preparing the tackifier, the temperature of the addition reaction is 50 to 70°C; more preferably, 55 to 65°C.

[0051] Preferably, in the method for preparing the tackifier, the addition reaction time is 1 to 4 hours; more preferably, it is 1.5 to 3 hours.

[0052] Preferably, in the method for preparing the tackifier, the addition reaction is carried out under vacuum conditions.

[0053] Preferably, the raw material of component A further includes polydimethylsiloxane.

[0054] Preferably, the mass percentage of the polydimethylsiloxane in the raw material of the component A is 1 to 10%; more preferably 2 to 8%; and even more preferably 3 to 5%.

[0055] In some specific embodiments of the present invention, the A component includes the following raw materials in parts by mass: 40 to 70 parts of a first double-ended vinyl polysiloxane, 100 to 200 parts of a first aluminum hydroxide, 1 to 5 parts of a silane coupling agent, and 0.1 to 1 part of a catalyst; the B component includes the following raw materials: 20 to 40 parts of a second double-ended vinyl polysiloxane, 10 to 25 parts of a double-ended hydrogen-containing polysiloxane, 1 to 10 parts of a side hydrogen-containing polysiloxane, 100 to 200 parts of a second aluminum hydroxide, 1 to 5 parts of a silane coupling agent, 0.1 to 0.5 parts of an inhibitor, and 1 to 10 parts of a tackifier; the mass ratio of the A component to the B component is 1:(0.5 to 1.5).

[0056] In some more specific embodiments of the present invention, the A component includes the following raw materials in parts by mass: 50 to 60 parts of a first double-ended vinyl polysiloxane, 130 to 170 parts of a first aluminum hydroxide, 2 to 3 parts of a silane coupling agent, and 0.3 to 0.7 parts of a catalyst; the B component includes the following raw materials: 23 to 27 parts of a second double-ended vinyl polysiloxane, 13 to 20 parts of a double-ended hydrogen-containing polysiloxane, 2 to 6 parts of a side hydrogen-containing polysiloxane, 130 to 170 parts of a second aluminum hydroxide, 2 to 3 parts of a silane coupling agent, 0.15 to 0.3 parts of an inhibitor, and 2 to 6 parts of a tackifier; the mass ratio of the A component to the B component is 1:(0.8 to 1.2).

[0057] In some other specific embodiments of the present invention, the component A includes the following raw materials in parts by mass: 40 to 70 parts of a first double-ended vinyl polysiloxane, 3 to 15 parts of polydimethylsiloxane, 100 to 200 parts of a first aluminum hydroxide, 1 to 5 parts of a silane coupling agent, and 0.1 to 1 part of a catalyst; the component B includes the following raw materials: 20 to 40 parts of a second double-ended vinyl polysiloxane, 10 to 25 parts of a double-ended hydrogen-containing polysiloxane, 1 to 10 parts of a side hydrogen-containing polysiloxane, 100 to 200 parts of a second aluminum hydroxide, 1 to 5 parts of a silane coupling agent, 0.1 to 0.5 parts of an inhibitor, and 1 to 10 parts of a tackifier; the mass ratio of the component A to the component B is 1:(0.5 to 1.5).

[0058] In some other more specific embodiments of the present invention, the A component includes the following raw materials in parts by mass: 50 to 60 parts of a first double-terminal vinyl polysiloxane, 5 to 10 parts of polydimethylsiloxane, 130 to 170 parts of a first aluminum hydroxide, 2 to 3 parts of a silane coupling agent, and 0.3 to 0.7 parts of a catalyst; the B component includes the following raw materials: 23 to 27 parts of a second double-terminal vinyl polysiloxane, 13 to 20 parts of a double-terminal hydrogen-containing polysiloxane, 2 to 6 parts of a side hydrogen-containing polysiloxane, 130 to 170 parts of a second aluminum hydroxide, 2 to 3 parts of a silane coupling agent, 0.15 to 0.3 parts of an inhibitor, and 2 to 6 parts of a tackifier; the mass ratio of the A component to the B component is 1:(0.8 to 1.2).

[0059] The second aspect of the present invention provides a method for preparing the organic silicone adhesive described in the first aspect of the present invention, comprising the following steps: mixing a first double-ended vinyl polysiloxane with a first silane coupling agent, adding a first aluminum hydroxide to mix, and finally adding a catalyst to mix to obtain component A; mixing a second double-ended vinyl polysiloxane with a second silane coupling agent, adding a second aluminum hydroxide to mix, and finally adding a double-ended hydrogen-containing polysiloxane, a side hydrogen-containing polysiloxane, a tackifier and an inhibitor to mix to obtain component B.

[0060] In some specific embodiments of the present invention, when the raw materials of the A component further include polydimethylsiloxane, the first dual-terminal vinyl polysiloxane, polydimethylsiloxane and the first silane coupling agent are mixed together.

[0061] The third aspect of the present invention provides a use of the organic silicone adhesive described in the first aspect of the present invention in preparing a high-voltage power supply.

[0062] In some specific embodiments of the present invention, the voltage of the high voltage power supply is ≥5kV.

[0063] The beneficial effects of the present invention are as follows: the present invention utilizes a specific tackifier, combines double-terminal vinyl polysiloxane and double-terminal hydrogen-containing polysiloxane as chain extenders, and side hydrogen-containing polysiloxane as a cross-linking agent, and simultaneously uses aluminum hydroxide with relatively low electrical conductivity, so that the prepared organic silicone adhesive has the advantages of excellent fluidity, high thermal conductivity, high flame retardancy, and good voltage resistance, and has good bonding properties to substrates such as PCB and aluminum, and can meet the requirements of high-voltage power supply for waterproofing, moisture-proofing, insulation, and heat dissipation.

[0064] Specifically, compared with the prior art, the present invention has the following advantages:

[0065] 1. The tackifier of the present invention grafts epoxy and methoxy groups on triallyl isocyanurate, which can improve the bonding properties of the organic silicone adhesive, and effectively improve the waterproofness and high-voltage resistance of the organic silicone adhesive, so that it has a good protective effect on the high-voltage power supply after long-term high and low temperature, high-temperature shock and soaking in water.

[0066] 2. The adhesive of the present invention can be used as a potting adhesive to achieve effective bonding with substrates such as PCB and aluminum, thereby obtaining a high-voltage power supply with good waterproof, moisture-proof, insulating and heat dissipation properties. When the high-voltage power supply is in high and low temperatures or other aging conditions, the adhesive of the present invention can still maintain excellent bonding performance with the PCB board or the housing, ensuring that the high-voltage power supply will not be broken down, thereby increasing the service life and safety performance of the high-voltage power supply.

[0067] 3. The present invention uses aluminum hydroxide with specific conductivity and particle size composition, combined with double-terminal vinyl polysiloxane, double-terminal hydrogen-containing polysiloxane and side hydrogen-containing polysiloxane with low total content of D3-D10, which is beneficial to further improve the bonding performance and waterproof, moisture-proof, insulating and heat dissipation properties of the adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 The synthetic method roadmap of the tackifier embodiment 1 of the present invention is shown in FIG.

[0069] Figure 2 This is a diagram of the volume resistivity test process of adhesive Example 1 of the present invention.

[0070] Figure 3 The figure is a schematic diagram of the structure of a high voltage power supply made by using the adhesive of the present invention. DETAILED DESCRIPTION

[0071] The content of the present invention is further described in detail below through specific examples. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the principles set forth in the present invention all belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific data exemplified below. The raw materials, reagents or devices used in the following examples and comparative examples, unless otherwise specified, can all be obtained from conventional commercial sources, or can be obtained by existing known methods.

[0072] Aluminum hydroxide Example 1

[0073] A refined aluminum hydroxide, denoted as refined aluminum hydroxide 1, has the following specific preparation steps:

[0074] Take 500g of commercially available 2μm and 10μm aluminum hydroxide (conductivity ≥80μS / m), add 1000g of high-purity boiling water respectively, stir for 2h, centrifuge while hot for 30min, and pour out the supernatant; after drying and grinding the powder, 2μm refined aluminum hydroxide 1 and 10μm refined aluminum hydroxide 1 are obtained respectively, and the conductivity of both is ≤5μS / m.

[0075] Aluminum hydroxide Example 2

[0076] A refined aluminum hydroxide, denoted as refined aluminum hydroxide 2, has the following specific preparation steps:

[0077] Take 500g of commercially available 2μm and 10μm aluminum hydroxide (conductivity ≥80μS / m), add 1000g of high-purity water respectively, stir for 2h, centrifuge for 30min, and pour out the supernatant; after drying and grinding the powder, 2μm refined aluminum hydroxide 2 and 10μm refined aluminum hydroxide 2 are obtained respectively, and the conductivity of both is ≤20μS / m.

[0078] Tackifier Example 1

[0079] A tackifier, comprising 34 wt% of a non-adductor, 51 wt% of an adductor 1 and 15 wt% of an adductor 2;

[0080] Among them, the chemical formula of adduct 1 is:

[0081] The chemical formula of adduct 2 is:

[0082] The chemical formula of the unadducted form is:

[0083] The reaction formula of the synthesis process of the above-mentioned tackifier is as follows:

[0084]

[0085] The synthetic method route of the above-mentioned tackifier is as follows Figure 1 As shown, the specific steps are as follows:

[0086] Step 1: Synthesis of sodium isocyanurate:

[0087] 1) Take 210g of isocyanuric acid and 800g of H2O, add them into a 2L four-necked flask, place it in a 70°C water bath, add 48% sodium hydroxide solution dropwise while stirring, and react for 2h after the addition is complete;

[0088] 2) After the reaction is completed, the water is vacuum-dried, washed with methanol for multiple times, and dried to obtain sodium isocyanurate powder;

[0089] Step 2: Synthesis of triallyl isocyanurate:

[0090] 1) Add 100 g of sodium isocyanurate obtained in step 1 and 200 g of 3-bromopropylene in DMF into a flask, set the temperature to 125° C., start stirring, and react for 6 hours;

[0091] 2) Then filter out the inorganic salt. The supernatant is extracted with toluene, washed with a large amount of water, and dried to remove the solvent to obtain 100 g of triallyl isocyanurate (Mw = 249.3);

[0092] Step 3: Synthesis of diallyl monoglycidyl isocyanurate:

[0093] 1) Take 100 g of triallyl isocyanurate in step 2, add 800 g of DCM solution, stir evenly, then add m-chloroperbenzoic acid dropwise at a temperature not exceeding 30° C., and react at room temperature for 4 h;

[0094] 2) Slowly add 2000g of 10% sodium bisulfite solution to the cooling water at 20°C, quench and filter;

[0095] 3) adding chloroform for extraction, and washing the reactant thoroughly with 10% sodium bisulfite solution and saturated sodium bicarbonate solution; after drying and distilling the solvent, an epoxy compound, namely diallyl monoglycidyl isocyanurate, is obtained;

[0096] Step 4: Synthesize the required tackifier through diallyl monoglycidyl isocyanurate:

[0097] Take 100 g of diallyl monoglycidyl isocyanurate obtained in step 3 and put it into a 500 ml three-necked flask, add a mixture of 30 g of trimethoxysilane and 100 g of toluene dropwise, react at 60° C. under vacuum for 2 h, and distill to obtain the desired tackifier.

[0098] In the following adhesive examples, some of the raw material information used is as follows:

[0099] (1) Double-terminated vinyl polysiloxane 1: 25°C viscosity of 100 mPa·s; vinyl content of 0.3 wt% to 1.2 wt%; small molecule organic silicon ring body D3 to D10 ≤ 300 ppm; specific chemical formula: In formula (IV), D is 10-500.

[0100] Double-terminated vinyl polysiloxane 2: The difference from double-terminated vinyl polysiloxane 1 is the purity. The content of small molecule organic silicon ring bodies D3 to D10 in double-terminated vinyl polysiloxane 2 is 1000 to 5000 ppm.

[0101] (2) Hydrogen-terminated polysiloxane 1: Viscosity at 25°C is 100-600 mPa·s; hydrogen content is 0.015-0.05 wt%; small molecule organosilicon ring body D3-D10 is ≤300 ppm; specific chemical formula is In formula (V), D is 20-300.

[0102] Terminal hydrogen-containing polysiloxane 2: The difference between terminal hydrogen-containing polysiloxane 1 and terminal hydrogen-containing polysiloxane 2 is the purity. The content of small molecule organosilicon ring bodies D3 to D10 in terminal hydrogen-containing polysiloxane 2 is 1000 to 5000 ppm.

[0103] (3) Side hydrogenated polysiloxane 1: 25°C viscosity of 40-110 mPa·s; hydrogen content of 0..08-0.3 wt%; small molecule organosilicon ring D3-D10 ≤ 300 ppm; specific chemical formula: In formula (VI), D is 20-80, and D' is 5-10.

[0104] Side-containing hydrogenated polysiloxane 2: The side-containing hydrogenated polysiloxane 1 is different in purity. The content of small molecular organic silicon ring bodies D3 to D10 in side-containing hydrogenated polysiloxane 2 is 1000 to 5000 ppm.

[0105] (4) Commercially available aluminum hydroxide: conductivity ≥80μS / m.

[0106] (5) Polydimethylsiloxane: commonly available on the market.

[0107] (6) Inhibitor: acetylene cyclohexanol, commonly available on the market.

[0108] Adhesive Example 1

[0109] An adhesive is composed of component A and component B, wherein the mass ratio of component A to component B is 1:1; the specific preparation steps are as follows:

[0110] Preparation of component A:

[0111] Accurately weigh 5400g of double-terminal vinyl polysiloxane 1 with a viscosity of 100mPa·s at 25°C, place it in a double planetary stirring kettle with a heating and vacuum system, add 220g of silane coupling agent, and heat to 100°C; add 10000g of 10μm refined aluminum hydroxide 1 and 4400g of 2μm refined aluminum hydroxide 1 in batches, set the stirring revolution to 60r / min and the rotation to 1500r / min, and treat for 60min. Turn off the heating and cool to below 45°C through circulating water. Add 50g of Pt catalyst (Heraeus 3000ppm Karestedt diluent), stir the revolution to 60r / min and the rotation to 1500r / min, and stir in vacuum at room temperature for 30min to obtain component A.

[0112] Preparation of component B:

[0113] Accurately weigh 3000kg of double-terminal vinyl polysiloxane 1 with a viscosity of 100mPa·s at 25°C, place it in a double planetary stirring kettle with a heating and vacuum system, add 220g of silane coupling agent, and heat to 100°C; add 10000g of 10μm refined aluminum hydroxide 1 and 4400g of 2μm refined aluminum hydroxide 1 in batches, set the stirring revolution to 60r / min and the rotation to 1500r / min, and treat for 60min. Turn off the heating and cool to below 45°C through circulating water. Add 1600g of chain extender-end hydrogen-containing polysiloxane 1, 400g of cross-linker-side hydrogen-containing polysiloxane 1, 400g of the tackifier obtained in Example 1 of the tackifier, and 20g of an inhibitor, stir the revolution to 60r / min, rotate at 1500r / min, and stir in vacuum at room temperature for 30min to obtain component B.

[0114] Adhesive Example 2

[0115] An adhesive, which is different from Adhesive Example 1 in that the aluminum hydroxide in this example is selected from 10 μm refined aluminum hydroxide 2 and 2 μm refined aluminum hydroxide 2 prepared in Aluminum Hydroxide Example 2, and the specific amount is shown in Table 1. Other raw materials and preparation steps are the same as those in Adhesive Example 1.

[0116] Adhesive Example 3

[0117] An adhesive, which differs from Adhesive Example 1 in that this example uses double-terminal vinyl polysiloxane 2, double-terminal hydrogen-containing polysiloxane 2 and side hydrogen-containing polysiloxane 2, and the specific amounts are shown in Table 1. Other raw materials and preparation steps are the same as those of Adhesive Example 1.

[0118] Adhesive Example 4

[0119] An adhesive, which is different from Adhesive Example 1 in that the amount of raw materials used is different, and polydimethylsiloxane is added, and the specific amount of raw materials used is shown in Table 1. Other raw materials and preparation steps are the same as those of Adhesive Example 1.

[0120] Adhesive Comparative Example 1

[0121] An adhesive, which is different from Adhesive Example 1 in that the aluminum hydroxide in this example is selected from 10 μm commercial aluminum hydroxide and 2 μm commercial aluminum hydroxide, and the specific amount is shown in Table 1. Other raw materials and preparation steps are the same as those in Adhesive Example 1.

[0122] Adhesive Comparative Example 2

[0123] An adhesive, which differs from Adhesive Example 1 in that no tackifier is added to component B of this example, and the reduced portion is supplemented by double-terminal vinyl polysiloxane 1, and the specific formula composition is shown in Table 1. Other raw materials and preparation steps are the same as those of Adhesive Example 1.

[0124] Adhesive Comparative Example 3

[0125] An adhesive, which differs from Adhesive Example 2 in that no silane coupling agent is added in this example, and the aluminum hydroxide is selected from 10 μm refined aluminum hydroxide 2 and 2 μm refined aluminum hydroxide 2 prepared in Aluminum Hydroxide Example 2, and the specific formula composition is shown in Table 1. Other raw materials and preparation steps are the same as those in Adhesive Example 2.

[0126] Adhesive Comparative Example 4

[0127] An adhesive, which is different from Adhesive Example 1 in that the tackifier is replaced with an equal amount of KH560 tackifier in this example. Other raw materials and preparation steps are the same as those of Adhesive Example 1.

[0128] Adhesive Comparative Example 5

[0129] An adhesive, which differs from Adhesive Example 1 in that the aluminum hydroxide is replaced by 20 μm silicon micropowder and 2 μm silicon micropowder in this example, and the specific amounts are shown in Table 1. Other raw materials and preparation steps are the same as those of Adhesive Example 1.

[0130] Table 1 Formulations of Adhesive Examples 1 to 4 and Adhesive Comparative Examples 1 to 5 (Unit: 100 g)

[0131]

[0132]

[0133] Performance Testing

[0134] 1) Hardness test (Shore A): First weigh the A and B components in a weight ratio of 1:1 (±5% deviation allowed), stir manually for 2 minutes, and evacuate for 5 minutes. As for curing at the specified temperature, use the Shore A hardness tester to test, please refer to GB / T 2411-2008 for details.

[0135] 2) Thermal conductivity test (W / m·K): Hotdisk, reference standard ISO 22007, 50g of each component A and B, test after vacuum curing, parameter 10s / 80mW; sample size: 3pcs.

[0136] 3) Shear strength test (KV / mm): Mix components A and B in a weight ratio of 1:1 within 3 minutes, adhere to the substrate PCB, fix it in an overlapping manner, and the thickness of the adhesive layer is 0.2mm; cure it according to the specified curing conditions (120℃ / 60min), and use a tensile machine to test after curing. The tensile speed is 10mm / min. Reference standard: GB / T 7124-2008.

[0137] Destruction form judgment criteria:

[0138] Level 1: After the mechanical machine is pulled apart, cracks appear inside the adhesive layer, and there is potting glue remaining on the substrate;

[0139] Level 2: After being pulled apart by a mechanical machine, cracks appear at the bonding interface, and very little potting glue remains on the substrate (residual glue area ≥ 10%);

[0140] Level 3: Cracks occur at the bonding interface after being pulled apart by a mechanical machine, and there is no potting glue residue on the interface.

[0141] 4) Breakdown voltage test (kV / mm): Mix components A and B in a weight ratio of 1:1 within 3 minutes, squeeze them into a special mold and lay them flat into a test piece with a thickness of (2.0±0.2) mm. Curing is carried out according to the specified curing conditions (85℃ / 30min). After curing, use a cutter to cut into 40×40mm test pieces and test them with a voltage breakdown tester. Reference standard: GB / T1695-2005.

[0142] 5) Volume resistivity test (Ω·cm): Mix components A and B in a weight ratio of 1:1 and squeeze them into a special mold to form a test piece with a thickness of (2.0±0.2) mm. After curing, cut them into round test pieces with a diameter of 85±0.5 mm and test them using a high insulation resistance tester. Refer to GB / T1692-2008. Taking adhesive embodiment 1 as an example, the volume resistivity test process is shown in the figure below: Figure 2 As shown, (a) is a photo of a high insulation resistance tester, (b) is a photo of a special test mold with a test sample placed thereon, and (c) is a photo of the special test mold being placed in the high insulation resistance tester for testing.

[0143] The above performance test data is shown in Table 2.

[0144] Table 2 Performance test data of adhesive examples 1 to 4 and adhesive comparative examples 1 to 5

[0145]

[0146]

[0147] From Table 2, by comparing adhesive examples 1-2 and adhesive comparative examples 1-3, it is found that the breakdown voltage of the potting glue prepared by using aluminum hydroxide washed with boiling water is slightly higher than that of normal water washing; the breakdown voltage of aluminum hydroxide potting glue using fine washing or surface modification is more than 30% higher than that of untreated aluminum hydroxide potting glue, and the breakdown voltage of aluminum hydroxide potting glue that has not been treated with fine washing drops significantly after being soaked in water for 100 hours. From the results of adhesive examples 3-4, it can be seen that the use of low molecular weight (D3-D10≤300ppm) silicone oil or the introduction of non-reactive polydimethylsiloxane can increase the breakdown voltage of the colloid. By comparing the adhesive example 1 with the adhesive comparative examples 2 and 4, it is found that the two structures of the tackifier obtained in the tackifier example 1 and the KH560 tackifier can form adhesion to the PCB, but the KH560 tackifier fails to bond after being soaked in water for 100 hours, which reduces the waterproof sealing effect of the high-voltage power supply and poses a safety hazard; at the same time, the addition of the tackifier has a certain negative impact on the breakdown voltage. In the adhesive comparative example 5, silicon micropowder is used to replace aluminum hydroxide, and the flame retardant grade of the obtained product is only V2, and it cannot form effective adhesion to the PCB.

[0148] The organic silicone adhesive obtained from the adhesive examples 1 to 4 of the present invention is used as a potting adhesive to prepare a high voltage power supply, and its structural schematic diagram is shown in FIG. Figure 3 As shown, if the potting glue and the PCB are not effectively bonded, a gap may be generated between the glue and the PCB under high and low temperature of the power supply or other aging conditions, so that the two high-voltage components of the high-voltage power supply may break through the air, causing power supply abnormality. The organic silicone adhesive obtained by the adhesive embodiments 1 to 4 of the present invention has good bonding performance with the PCB, and its use as a potting glue will greatly improve the safety of the high-voltage power supply.

[0149] The tackifier in the embodiment of the present invention grafts epoxy and methoxy groups on triallyl isocyanurate, which can improve the bonding performance of the organic silicone adhesive, and effectively improve the waterproofness and high-voltage resistance of the organic silicone adhesive, so that it has a good protective effect on the high-voltage power supply after long-term high and low temperature, high-temperature shock and soaking in water. In addition, the aluminum hydroxide with a specific conductivity and particle size composition is used in the embodiment of the present invention, combined with a double-terminal vinyl polysiloxane with a low total content of D3 to D10, a double-terminal hydrogen-containing polysiloxane and a side hydrogen-containing polysiloxane, which is conducive to further improving the bonding performance and waterproof, moisture-proof, insulating and heat dissipation properties of the adhesive.

[0150] The adhesive provided in the embodiment of the present invention can be used as a potting adhesive to achieve effective bonding with substrates such as PCB and aluminum, thereby obtaining a high-voltage power supply with good waterproof, moisture-proof, insulating and heat dissipation performance. When the high-voltage power supply is in high and low temperatures or other aging conditions, the adhesive of the present invention can still maintain excellent bonding performance with the PCB board or the housing, ensuring that the high-voltage power supply will not be broken down, thereby increasing the service life and safety performance of the high-voltage power supply.

[0151] In summary, the present invention utilizes a specific tackifier, combines a double-terminal vinyl polysiloxane and a double-terminal hydrogen-containing polysiloxane as a chain extender, and a side hydrogen-containing polysiloxane as a cross-linking agent, and uses aluminum hydroxide with relatively low electrical conductivity. The prepared organic silicone adhesive has the advantages of excellent fluidity, high thermal conductivity, high flame retardancy, and good voltage resistance, and has good bonding properties to substrates such as PCB and aluminum, and can meet the requirements of high-voltage power supply for waterproofing, moisture-proofing, insulation and heat dissipation.

Claims

1. An organic silicone adhesive, characterized in that: It includes component A and component B; the component A includes the following raw materials: The first double-terminal vinyl polysiloxane, the first aluminum hydroxide, the first silane coupling agent, and the catalyst; the B component includes the following raw materials: the second double-terminal vinyl polysiloxane, the double-terminal hydrogen-containing polysiloxane, the side hydrogen-containing polysiloxane, the second aluminum hydroxide, the second silane coupling agent, the inhibitor, and the tackifier; The electrical conductivity of the first aluminum hydroxide and the electrical conductivity of the second aluminum hydroxide are each independently less than or equal to 30 μS / m; The adhesion promoter is selected from triallyl isocyanurate grafted with epoxy and methoxy groups.

2. The organic silicone adhesive according to claim 1, characterized in that: The particle size of the first aluminum hydroxide and the particle size of the second aluminum hydroxide are each independently 1 to 15 μm.

3. The organic silicone adhesive according to claim 1 or 2, characterized in that: The first aluminum hydroxide and the second aluminum hydroxide each independently include first particles and second particles. The first particles have a particle size of 1 to 5 μm, and the second particles have a particle size of 5 to 15 μm.

4. The organic silicone adhesive according to claim 1, characterized in that: The total content of small molecule organosilicon ring bodies D3 to D10 of the first double-terminal vinyl polysiloxane and the total content of small molecule organosilicon ring bodies D3 to D10 of the second double-terminal vinyl polysiloxane are each independently less than or equal to 500 ppm; And / or, the total content of the small molecule organosilicon ring bodies D3-D10 of the double-terminal hydrogen-containing polysiloxane is less than or equal to 500 ppm; and / or, the total content of the small molecule organosilicon ring bodies D3-D10 of the side hydrogen-containing polysiloxane is independently less than or equal to 500 ppm.

5. The organic silicone adhesive according to claim 1, characterized in that: The viscosity of the first dual-end vinyl polysiloxane at 25° C. and the viscosity of the second dual-end vinyl polysiloxane at 25° C. are each independently 50 to 5000 mPa·s; and / or, the vinyl content of the first double-terminal vinyl polysiloxane and the vinyl content of the second double-terminal vinyl polysiloxane are each independently 0.2 to 2 wt%; and / or, the viscosity of the double-terminal hydrogen-containing polysiloxane at 25° C. is 10 to 1000 mPa·s; And / or, the hydrogen content of the double-terminal hydrogen-containing polysiloxane is 0.01 to 0.18 wt%; and / or, the viscosity of the side hydrogen-containing polysiloxane at 25° C. is 40 to 200 mPa·s; and / or, the hydrogen content of the side hydrogenated polysiloxane is 0.08 to 0.3 wt %; And / or, the catalyst is selected from a platinum catalyst; the platinum catalyst includes at least one of a divinyltetramethyldisiloxane platinum complex, a divinyloctamethyltetrasiloxane platinum complex or a chloroplatinic acid alcohol solution; And / or, the inhibitor includes at least one of acetylene cyclohexanol, methyl butynol, tetramethyl divinyl disiloxane or trimethyl-dodecynol.

6. The organic silicone adhesive according to claim 1, characterized in that: The first silane coupling agent and the second silane coupling agent each independently include a methoxy mono-terminated silane coupling agent, an ethoxy mono-terminated silane coupling agent or a combination thereof; And / or, the chemical formula of the first silane coupling agent and the chemical formula of the second silane coupling agent are each independently represented by the following formula (VII): In formula (VII), R1 is a C1-C5 alkyl group; R2 is a C1-C5 alkyl group; x is 1-12; n is 10-60; and m is 1-3.

7. The organic silicone adhesive according to claim 1, characterized in that: The A component comprises the following raw materials in parts by weight: 40 to 70 parts of a first double-terminal vinyl polysiloxane, 100 to 200 parts of a first aluminum hydroxide, 1 to 5 parts of a silane coupling agent, and 0.1 to 1 part of a catalyst; the B component comprises the following raw materials: 20 to 40 parts of a second double-terminal vinyl polysiloxane, 10 to 25 parts of a double-terminal hydrogen-containing polysiloxane, 1 to 10 parts of a side hydrogen-containing polysiloxane, 100 to 200 parts of a second aluminum hydroxide, 1 to 5 parts of a silane coupling agent, 0.1 to 0.5 parts of inhibitor, 1 to 10 parts of viscosity enhancer; the mass ratio of the component A to the component B is 1:(0.5 to 1.5).

8. The organic silicone adhesive according to claim 1, characterized in that: The raw materials of component A also include polydimethylsiloxane; the mass percentage of the polydimethylsiloxane in the raw materials of component A is 1-10%.

9. A method for preparing the organic silicone adhesive according to any one of claims 1 to 8, characterized in that: The following steps are involved: The first double-terminal vinyl polysiloxane is mixed with the first silane coupling agent, and then the first aluminum hydroxide is added to mix, and finally the catalyst is added to mix to obtain component A; the second double-terminal vinyl polysiloxane is mixed with the second silane coupling agent, and then the second aluminum hydroxide is added to mix, and finally the double-terminal hydrogen-containing polysiloxane, the side hydrogen-containing polysiloxane, the tackifier and the inhibitor are added to mix to obtain component B.

10. Use of the organic silicone adhesive according to any one of claims 1 to 8 in preparing a high voltage power supply.

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