A powder surface modifier and modified powder and preparation method and application thereof

Abstract

The present invention relates to a powder surface modifier and a preparation method and application of the modified powder. The powder surface modifier prepared by the present invention can take into account the good processing technology, high thermal conductivity and softness of the filled silicone gel, greatly improve the competitiveness of organic silicon thermal conductive products, and can be widely used in electronic components, communication base stations, new energy batteries, charging piles and other electronic thermal conductive packaging fields.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal interface materials, and relates to a powder surface modifier, a modified powder, and preparation methods and applications thereof. Background Art

[0002] As electronic products develop towards high integration, multi-function and miniaturization, the packaging density of electronic components or power devices has also increased dramatically. Heat accumulation will cause electronic components to overheat, reducing their reliability and life. Filling the micro gaps generated by the contact between two materials with thermal interface materials, reducing heat transfer impedance and improving heat dissipation performance is of great significance for protecting the normal operation of electronic components such as chips and extending their service life.

[0003] The structure of thermal interface materials currently used on a large scale is mainly of the filling type, that is, a large amount of thermally conductive powder is added to the base material to realize the thermal conductivity of the interface material. One of the products currently widely used in the market is a system of thermally conductive powder filled with silicone, such as thermally conductive silicone grease, thermally conductive gel, thermally conductive gasket, etc. The large amount of thermally conductive powder can significantly improve the thermal conductivity of thermal interface materials. However, in addition to high thermal conductivity, thermal interface materials for electronic components also require good construction technology and good softness of materials. For example, high thermal conductivity silicone gel requires a high filling amount of thermal conductive filler while maintaining a low viscosity. For example, when the filling amount is greater than 90wt.%, the modulus is required to be less than 40KPa and the elongation at break is greater than 150%. However, thermally conductive metal powders (silver powder, aluminum powder, etc.) have large surface polarity, large specific surface area, high surface energy, strong interaction between powder particles and are very easy to agglomerate. After entering the matrix, they have strong interaction with the matrix, resulting in a sharp increase in the viscosity of the filling system and a sharp increase in the hardness of the material. It can be seen that it is difficult to take into account both the filling amount of thermal conductive powder and the viscosity and softness of the filled system. Therefore, one of the key technical difficulties in preparing thermal interface materials is the surface treatment of the filler to improve the interaction between filler-filler and filler-matrix to achieve comprehensive excellent performance. Summary of the invention

[0004] In order to improve the above technical problems, the present invention provides a powder surface modifier, a modified powder comprising the powder surface modifier, and preparation methods and applications thereof.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] A powder surface modifier, the modifier having a structural formula shown in Formula I:

[0007]

[0008] In Formula I, R1 is selected from C 1-10 Alkyl, C 2-10Any of alkenyl;

[0009] R2, R3, R4, R5 are the same or different and are independently selected from H, C 1-10 Alkyl, C 2-10 Alkenyl, C 6-14 Aryl, one or more R s Substituted C 1-10 Any of the alkyl groups, wherein R s Any one selected from halogen and cyano;

[0010] R6 are the same or different and are independently selected from alkyl groups;

[0011] x is selected from a natural number between 10 and 200, y is selected from a natural number between 1 and 10, and z is selected from a natural number between 10 and 200.

[0012] The present invention also provides a method for preparing the powder surface modifier, which comprises the following steps:

[0013] 1) mixing aminopropyltrialkoxysilane, 5-norbornene 2-carboxylic acid, a first solvent and a first catalyst in a certain proportion, and reacting at room temperature for a period of time to obtain an aminopropyltrialkoxysilane norbornene reactant;

[0014] 2) mixing the single-end hydroxyl polysiloxane, 5-norbornene 2-carboxylic acid, a second solvent, a second catalyst, and a dehydrating agent in a certain proportion and reacting them at room temperature for a period of time, adding two times the volume of methanol or ethanol for separation, taking the clear liquid, and vacuum-evacuating the residual solvent to obtain the single-end norbornene functionalized polysiloxane;

[0015] 3) In an anhydrous and oxygen-free environment, the single-end norbornene functionalized polysiloxane in step 2), the third solvent, and the third catalyst are uniformly mixed in a certain proportion, and after pre-reaction at room temperature for a period of time, a certain amount of the silane coupling agent-norbornene condensate in step 1) is added to continue to react at room temperature for a period of time, and the solvent is removed in vacuo to obtain the powder surface modifier.

[0016] The present invention also provides a modified powder, which comprises a powder and the above-mentioned powder surface modifier located on the surface of the powder.

[0017] The present invention further provides uses of the modified powder, wherein the modified powder is used in the fields of heat conduction, electricity conduction or electromagnetic shielding.

[0018] The present invention further provides a method for preparing the modified powder, which comprises the following steps:

[0019] The powder surface modifier, powder, fourth solvent and fourth catalyst are uniformly mixed in a certain proportion, fully reacted at a certain temperature for a period of time, condensed and refluxed, filtered, and vacuum dried to obtain the modified powder.

[0020] The present invention also provides a thermally conductive gel, which comprises the modified powder.

[0021] The present invention also provides a method for preparing the thermally conductive gel, which comprises the following steps:

[0022] The modified powder is mixed with the raw material for forming the polysiloxane matrix in a certain proportion, kneaded, and cured to obtain the thermal conductive gel.

[0023] Beneficial Effects

[0024] The invention provides a powder surface modifier, wherein the molecular weight of the side chain polysiloxane in the brush-shaped structure of the modifier is lower than the entanglement molecular weight, and the side chain polysiloxane structure itself has no molecular chain entanglement, thereby ensuring a good brush-shaped structure.

[0025] The present invention also provides a method for preparing the powder surface modifier. The preparation method is a ring-opening metathesis polymerization (ROMP) method, which is an efficient and controllable active polymerization method with strong designability.

[0026] The present invention also provides a modified powder, which includes a powder and the above-mentioned powder surface modifier bonded to the surface of the powder. The single-end function of the modifier can chemically bond with the surface of the powder (such as filler), so that the modifier is firmly grafted on the surface of the powder, and the polarity of the powder surface is significantly reduced. At the same time, the modifier on the powder surface can further shield the polar force of the powder, greatly improving the agglomeration problem of the powder particles.

[0027] The present invention also provides a thermally conductive gel, which includes the above-mentioned modified powder and polysiloxane matrix. The modifier on the surface of the modified powder does not have chain entanglement with the polysiloxane matrix, and has good compatibility. It can not only shield the weak bond interaction between the powder surface and the polysiloxane main chain, but also play an interfacial lubrication role, greatly reducing the movement resistance of the powder in the polysiloxane. Therefore, the filling amount of the powder is greatly increased, the heat conduction path is further improved, and the thermal conductivity of the system is greatly improved. At the same time, the filling system still maintains a low viscosity, a high elongation at break and a low modulus at a high filling amount.

[0028] It can be seen that the technical solution of the present invention solves the technical problem of high thermal conductivity and low viscosity, low modulus and high elongation of thermal interface gel materials, which is of great significance for promoting the further development of high-end thermal conductive thermal interface materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the infrared spectrum of norbornene-modified polysiloxane macromolecular monomer;

[0030] Figure 2 This is the NMR spectrum of norbornene-modified polysiloxane macromolecular monomer;

[0031] Figure 3 This is the NMR spectrum of polysiloxane and alkoxysilane bottle brush copolymer;

[0032] Figure 4 Gel permeation chromatograms before and after polymerization;

[0033] Figure 5 The prepared surface modifier-modified powder is used as a thermal conductive filler and has excellent anti-aging properties. It maintains low modulus properties after aging for 2000h@125℃. DETAILED DESCRIPTION

[0034] In a first aspect, the present invention provides a powder surface modifier having a structural formula shown in Formula I:

[0035]

[0036] In Formula I, R1 is selected from C 1-10 Alkyl, C 2-10 Any of alkenyl;

[0037] R2, R3, R4, R5 are the same or different and are independently selected from H, C 1-10 Alkyl, C 2-10 Alkenyl, C 6-14 Aryl, one or more R s Substituted C 1-10 Any of the alkyl groups, wherein R s Any one selected from halogen and cyano;

[0038] R6 are the same or different and are independently selected from alkyl groups;

[0039] x is selected from a natural number between 10 and 200, y is selected from a natural number between 1 and 10, and z is selected from a natural number between 10 and 200.

[0040] In some technical solutions, R1 is selected from C 1-10 One of the alkyl groups may be illustratively a methyl group, an ethyl group, a propyl group or a butyl group.

[0041] In some technical schemes, R2, R3, R4, and R5 are the same or different, and are independently selected from methyl or propyl substituted with cyano.

[0042] In some technical solutions, R6 is selected from C 1-10 Any of the alkyl groups may illustratively be a methyl group or an ethyl group.

[0043] In a second aspect, the present invention provides a method for preparing the above-mentioned powder surface modifier, the preparation method comprising the following steps:

[0044] 1) mixing aminopropyltrialkoxysilane, 5-norbornene 2-carboxylic acid, a first solvent and a first catalyst in a certain proportion, and reacting at room temperature for a period of time to obtain an aminopropyltrialkoxysilane norbornene reactant;

[0045] 2) mixing the single-end hydroxyl polysiloxane, 5-norbornene 2-carboxylic acid, a second solvent, a second catalyst, and a dehydrating agent in a certain proportion and reacting them at room temperature for a period of time, adding two times the volume of methanol or ethanol for separation, taking the clear liquid, and vacuum-evacuating the residual solvent to obtain the single-end norbornene functionalized polysiloxane;

[0046] 3) In an anhydrous and oxygen-free environment, the single-end norbornene functionalized polysiloxane in step 2), the third solvent, and the third catalyst are uniformly mixed in a certain proportion, and after pre-reaction at room temperature for a period of time, a certain amount of the silane coupling agent-norbornene condensate in step 1) is added to continue to react at room temperature for a period of time, and the solvent is removed in vacuo to obtain the powder surface modifier.

[0047] In some technical solutions, the alkoxy group in the aminopropyltrialkoxysilane is C 1-10 Alkoxy group; specifically, the aminopropyltrialkoxysilane is selected from any one of aminopropyltrimethoxysilane and aminopropyltriethoxysilane.

[0048] In some technical schemes, the first solvent, the second solvent and the third solvent are the same or different and are independently selected from any one or more of dichloromethane, dichloroethane, dichloropropane and trichloromethane.

[0049] In some technical schemes, the first catalyst and the second catalyst are the same or different and are independently selected from any one or more of dimethylaminopyridine and pyrrolidinopyridine.

[0050] In some technical solutions, the third catalyst is selected from a ruthenium coordination catalyst, and illustratively may be a Grubbs III catalyst.

[0051] In some technical schemes, in step 1), the mass ratio of the aminopropyltrialkoxysilane, 5-norbornene 2-carboxylic acid, the first solvent, and the first catalyst is (40-60):(20-40):(40-60):(0.5-1.5), and illustratively can be 50:32:50:1.

[0052] In some technical solutions, in step 1), the reaction time is 0.5 hours to 5 hours, for example, 2 hours to 3 hours.

[0053] In some technical schemes, in step 2), the single-end hydroxyl polysiloxane is selected from any one or more of single-end hydroxyl polydimethylsiloxane, single-end hydroxyl polymethyltrifluoropropylsiloxane, single-end hydroxyl polymethylphenylsiloxane, single-end hydroxyl polyvinylmethylsiloxane, single-end hydroxyl polymethylcyanopropylsiloxane, single-end hydroxyl polymethylethylsiloxane and single-end hydroxyl polymethylethylsiloxane.

[0054] In some technical solutions, the molecular weight of the single-end hydroxyl polysiloxane is 1000-20000, specifically 1000, 2000, 5000, 10000, 20000.

[0055] In some technical solutions, the dehydrating agent in step 2) is, for example, dicyclohexylcarbodiimide DCC.

[0056] In some technical schemes, the mass ratio of the mono-terminal hydroxyl polysiloxane, 5-norbornene 2-carboxylic acid, the second solvent, the second catalyst, and the dehydrating agent in step 2) is (5-12):(0.2-0.8):(25-35):(0.01-0.04):(1-3), and illustratively can be 10:0.55:30:0.02:2.

[0057] In some technical solutions, in step 2), the reaction time is 2 hours to 20 hours, and illustratively can be 9 hours to 12 hours.

[0058] In some technical schemes, in step 3), the usage ratio of the single-end norbornene functionalized polysiloxane, the third solvent, the third catalyst, and the condensate of silane coupling agent-norbornene is (4-6) g:(40-60) g:(0.0001-0.02) g:(0.05-0.2) g, illustratively, it can be 5 g:50 g:(0.0006-0.012) g:0.1 g.

[0059] In some technical solutions, in step 3), the pre-reaction time is 2-20 minutes, illustratively 4 minutes; the time for continuing the reaction at room temperature is 20-120 minutes, illustratively 30 minutes.

[0060] In a third aspect, the present invention provides a modified powder, comprising a powder and the above-mentioned powder surface modifier located on the surface of the powder.

[0061] In some technical solutions, the powder surface modifier is bonded to the surface of the powder in the form of chemical bonds.

[0062] In some technical solutions, the powder is a thermally conductive powder. Specifically, the thermally conductive powder is selected from metal powder and / or metal oxide powder; illustratively, the thermally conductive powder is selected from any one or more of silver powder, copper powder, iron powder, aluminum powder, zinc powder, iron oxide, ferroferric oxide, zinc oxide, and iron oxide.

[0063] In some technical solutions, the shape of the powder includes sphere, flake, and irregular polyhedron.

[0064] In some technical solutions, the average particle size of the powder is 1 micron to 40 microns, illustratively 1 micron to 5 microns or 10 microns to 40 microns.

[0065] In a fourth aspect, the present invention provides a method for preparing the above-mentioned modified powder, the preparation method comprising the following steps: uniformly mixing the above-mentioned powder surface modifier, powder, a fourth solvent and a fourth catalyst in a certain proportion, fully reacting at a certain temperature for a period of time, condensing and refluxing, filtering, and vacuum drying to obtain the modified powder.

[0066] In some technical solutions, the powder has the definition described above.

[0067] In some technical schemes, the fourth solvent is selected from one or more of n-hexane, n-heptane, petroleum ether, chloroform, dichloromethane, ethyl ether, ethanol, acetone, and ethyl acetate.

[0068] In some technical solutions, the fourth catalyst is selected from one or more of organic tin, titanate, and ammonia.

[0069] In some technical schemes, the mass ratio of the powder surface modifier, the powder, the fourth solvent and the fourth catalyst is (1-5):(30-70):(5-20):(0.005-0.05), exemplarily 2:(50-70):10:0.001.

[0070] In some technical solutions, the reaction temperature is 45-100°C, illustratively 50°C.

[0071] In some technical solutions, the reaction time is 4 hours to 24 hours, illustratively 5 hours to 6 hours.

[0072] In a fifth aspect, the present invention also provides a use of the above-mentioned modified powder, which can be used in the fields of thermal conductivity, electrical conductivity or electromagnetic shielding.

[0073] In some technical solutions, it can be used as thermal conductive, conductive or electromagnetic shielding material in electronic components, communication base stations, new energy batteries, charging piles, etc.

[0074] In a sixth aspect, the present invention provides a thermally conductive gel, comprising the modified powder.

[0075] In some technical solutions, the thermally conductive gel includes a polysiloxane matrix and the above-mentioned modified powder filled in the matrix.

[0076] In some technical solutions, the raw materials for forming the polysiloxane matrix include vinyl-terminated silicone oil, hydrogen-terminated silicone oil, hydrogen-containing silicone oil, an inhibitor and a platinum catalyst.

[0077] In some technical schemes, the vinyl-terminated silicone oil is selected from any one or more of vinyl-terminated dimethyl silicone oil, vinyl-terminated methylphenyl silicone oil, vinyl-terminated diphenyl silicone oil, vinyl-terminated methyltrifluoropropyl silicone oil, vinyl-terminated methylethyl silicone oil, and vinyl-terminated methylcyano silicone oil.

[0078] In some technical solutions, the viscosity of the vinyl-terminated silicone oil is 50-1000 cp.

[0079] In some technical schemes, the hydrogen-terminated silicone oil is selected from one or more of hydrogen-terminated dimethyl silicone oil, hydrogen-terminated methylphenyl silicone oil, hydrogen-terminated diphenyl silicone oil, hydrogen-terminated methyltrifluoropropyl silicone oil, hydrogen-terminated methylethyl silicone oil, and hydrogen-terminated methylcyano silicone oil.

[0080] In some technical solutions, the viscosity of the hydrogen-containing silicone oil is 100-1000 cp.

[0081] In some technical solutions, the inhibitor is a compound containing a terminal olefin group or a terminal alkynyl group, for example, it can be any one of 3-methyl-1-butyn-3-ol and divinyltetramethylsilane or a combination thereof.

[0082] In some technical schemes, the mass ratio of modified powder, vinyl-terminated silicone oil, hydrogen-terminated silicone oil, hydrogen-containing silicone oil, inhibitor, and platinum catalyst is (800-1800):(60-70):(25-35):(0.5-1):(0.05-0.2):(0.1-0.4), exemplarily (900-1400):67:32:0.7:0.1:(0.1-0.2).

[0083] In a seventh aspect, the present invention provides a method for preparing the thermally conductive gel, the method comprising the following steps:

[0084] The modified powder and the raw material for forming the polysiloxane matrix are mixed in a certain proportion, kneaded, and solidified to obtain the thermal conductive gel.

[0085] In some technical schemes, the method specifically includes the following steps: the modified powder, vinyl-terminated silicone oil, hydrogen-terminated silicone oil, hydrogen-containing silicone oil, inhibitor and platinum catalyst are mixed evenly in a certain proportion, kneaded on three rollers, transferred into a mold after vacuum degassing at room temperature, and cured at 100°C for 2 hours to obtain a thermal conductive gel.

[0086] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0087] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0088] Example 1

[0089] Preparation of modifier: Take 5 g of KH550 (3-aminopropyltriethoxysilane), 3.2 g of NB-COOH (5-norbornene-2-carboxylic acid, exoform), and 5 g of DCM (dichloromethane), mix them evenly, add 0.1 g of 4-ppy (4-pyrrolidinopyridine), and react at room temperature for 2 hours to obtain the condensation product of KH550 and NB-COOH (NB-KH550).

[0090] Take 10 g of PDMS-OH (monohydroxypropyl-terminated polydimethylsiloxane, molecular weight of about 5000), 0.55 g of NB-COOH, and 30 g of DCM and mix them evenly. Add 2 g of DCC (dicyclohexylcarbodiimide) and 0.02 g of DMAP (4-dimethylaminopyridine). Incubate at room temperature for 12 hours, add twice the volume of methanol for liquid separation, take the lower clear liquid, and remove the residual DCM in vacuo to obtain the condensation product of PDMS-OH and NB-COOH (NB-PDMS).

[0091] In a glove box, 5 g of NB-PDMS was dissolved in 50 ml of DCM, 50 μl of G3 catalyst was added, and after reacting for 4 minutes, 0.1 g of NB-KH550 was added, and the reaction was continued for 30 minutes. The DCM solvent was removed by vacuum to obtain a PDMS bottle brush polymer modifier having a structure shown in Formula I, wherein x=10-200, y=1-10.

[0092] Specifically, Figure 1-4 A polymer structure characterization spectrum of the PDMS bottle brush polymer modifier is shown.

[0093] Preparation of modified powder: Take 2 grams of bottle brush polymer modifier and dissolve it in 10 grams of n-hexane, drop about 0.01 grams of organic tin catalyst, add 50 grams of aluminum powder (10 microns 67wt%, 3 microns 23wt%), stir thoroughly at 50°C, condense and reflux for 5 hours, filter, and vacuum dry the obtained powder at 80°C for 5 hours to obtain PDMS bottle brush polymer modified aluminum powder.

[0094] Preparation of thermal conductive gel: Take 900 parts of PDMS bottle brush polymer modified aluminum powder, 67 parts of terminal vinyl dimethyl silicone oil (viscosity 310cp), 32 parts of terminal hydrogen dimethyl silicone oil (viscosity 200cp), 0.7 parts of hydrogen-containing silicone oil (viscosity 1000cp), 0.1 parts of acetylene alcohol inhibitor, and 0.2 parts of platinum catalyst, mix them thoroughly, mix them with three rollers twice, and vacuum degas at room temperature for 30 minutes to obtain uncured thermal conductive grease. After transferring it into a mold, cure it at 100°C for 2 hours to obtain a paste-like thermal conductive gel.

[0095] Figure 5 The picture of the thermal conductive gel prepared in this example is shown. As shown in the figure, after aging at 125° C. for 2000 hours, the thermal conductive gel still has low modulus characteristics.

[0096] Example 2

[0097] Preparation of modifier: Take 5 grams of 3-aminopropyltrimethoxysilane (APTEOS), 3.2 grams of NB-COOH (5-norbornene-2-carboxylic acid, external form), and 5 grams of dichloroethane, mix them evenly, add 0.1 grams of dimethylaminopyridine, and react at room temperature for 3 hours to obtain the condensation product of 3-aminopropyltrimethoxysilane (APTEOS) and NB-COOH (NB-APTEOS).

[0098] Take 10 grams of PPMS-OH (monohydroxypropyl-terminated polymethylphenylsiloxane, molecular weight of about 6000), 0.55 grams of NB-COOH, and 30 grams of ethylene dichloride, mix them evenly, add 2 grams of dicyclohexylcarbodiimide and 0.02 grams of 4-dimethylaminopyridine, react at room temperature for 10 hours, add twice the volume of methanol for liquid separation, take the lower clear liquid, and vacuum remove the residual ethylene dichloride to obtain the condensation product of PPMS-OH and NB-COOH (NB-PPMS).

[0099] In a glove box, 5 g of NB-PPMS was dissolved in 50 ml of dichloroethane, 50 μl of G3 catalyst was added, and after reacting for 4 minutes, 0.1 g of NB-APTEOS was added, and the reaction was continued for 30 minutes. The dichloroethane solvent was removed by vacuum to obtain a PPMS bottle brush polymer modifier having a structure shown in Formula I, wherein x=10-200, y=1-10.

[0100] Preparation of modified powder: Take 2 grams of bottle brush polymer modifier and dissolve it in 10 grams of n-hexane, drop about 0.01 grams of organic tin catalyst, add 70 grams of silver powder (19 microns 72wt%, 2 microns 28wt%), stir thoroughly at 50°C, condense and reflux for 6 hours, filter, and vacuum dry the obtained powder at 80°C for 6 hours to obtain PDMS bottle brush polymer modified silver powder.

[0101] Preparation of thermal conductive gel: Take 1400 parts of PPMS bottle brush polymer modified silver powder, 67 parts of terminal vinyl methyl phenyl silicone oil (viscosity 310cp), 32 parts of terminal hydrogen methyl phenyl silicone oil (viscosity 200cp), 0.7 parts of hydrogen-containing silicone oil (viscosity 1000cp), 0.1 parts of acetylene alcohol inhibitor, and 0.2 parts of platinum catalyst, mix them thoroughly, mix them with three rollers twice, and vacuum degas at room temperature for 30 minutes to obtain uncured thermal conductive grease. After transferring it into a mold, cure it at 100°C for 2 hours to obtain a paste-like thermal conductive gel.

[0102] Example 3

[0103] Preparation of modifier: Take 5 g of KH550 (3-aminopropyltriethoxysilane), 3.2 g of NB-COOH (5-norbornene-2-carboxylic acid, external form), and 5 g of dichloromethane, mix them evenly, add 0.1 g of 4-pyrrolidinopyridine, and react at room temperature for 2 hours to obtain the condensation product of KH550 and NB-COOH (NB-KH550).

[0104] Take 10 grams of PCMS-OH (monohydroxypropyl-terminated polymethylcyanopropylsiloxane, molecular weight of about 5600), 0.55 grams of NB-COOH, and 30 grams of dichloromethane and mix them evenly. Add 2 grams of dicyclohexylcarbodiimide and 0.02 grams of 4-dimethylaminopyridine. Incubate at room temperature for 9 hours, add twice the volume of methanol for liquid separation, take the clear liquid, and remove the residual dichloromethane in vacuo to obtain the condensation product of PCMS-OH and NB-COOH (NB-PCMS).

[0105] In a glove box, 5 g of NB-PCMS was dissolved in 50 ml of dichloromethane, 50 μl of G3 catalyst was added, and after reacting for 4 minutes, 0.1 g of NB-KH550 was added, and the reaction was continued for 30 minutes. The dichloromethane was removed by vacuum to obtain a PCMS bottle brush polymer modifier having a structure shown in Formula I, wherein x=10-200, y=1-10.

[0106] Preparation of modified powder: Take 2 grams of bottle brush polymer modifier and dissolve it in 10 grams of n-hexane, drop about 0.01 grams of organic tin catalyst, add 55 grams of iron powder (20 microns 70wt%, 1 micron 30wt%), stir thoroughly at 50°C, condense and reflux for 5 hours, filter, and vacuum dry the obtained powder at 80°C for 5 hours to obtain PCMS bottle brush polymer modified iron powder.

[0107] Preparation of thermal conductive gel: Take 1200 parts of PCMS bottle brush polymer modified iron powder, 67 parts of terminal vinyl methyl cyano silicone oil (viscosity 310cp), 32 parts of terminal hydrogen methyl cyano silicone oil (viscosity 200cp), 0.7 parts of hydrogen-containing silicone oil (viscosity 1000cp), 0.1 parts of acetylene alcohol inhibition, and 0.2 parts of platinum catalyst, mix them thoroughly, mix them with three rollers twice, and vacuum degas at room temperature for 30 minutes to obtain uncured thermal conductive grease. After transferring it into a mold, cure it at 100°C for 2 hours to obtain a paste-like thermal conductive gel.

[0108] Comparative Example 1

[0109] Take 900 parts of aluminum powder (10 microns 67wt%, 3 microns 23wt%), 67 parts of terminal vinyl dimethyl silicone oil (viscosity 310cp), 32 parts of terminal hydrogen dimethyl silicone oil (viscosity 200cp), 0.7 parts of hydrogen-containing silicone oil (viscosity 1000cp), 0.1 parts of acetylene alcohol inhibitor, and 0.2 parts of platinum catalyst, mix them thoroughly, mix them with three rollers twice, and degas at room temperature under vacuum for 30 minutes to obtain uncured thermal grease. After transferring it into a mold, cure it at 100°C for 2 hours to obtain a paste-like thermal conductive gel.

[0110] Comparative Example 2

[0111] Take 1400 parts of silver powder (19 microns 72wt%, 2 microns 28wt%), 67 parts of terminal vinyl methyl phenyl silicone oil (viscosity 310cp), 32 parts of terminal hydrogen methyl phenyl silicone oil (viscosity 200cp), 0.7 parts of hydrogen-containing silicone oil (viscosity 1000cp), 0.1 parts of acetylene alcohol inhibitor, and 0.2 parts of platinum catalyst, mix them thoroughly, mix them with three rollers twice, and degas at room temperature under vacuum for 30 minutes to obtain uncured thermal grease. After transferring it into a mold, cure it at 100°C for 2 hours to obtain a paste-like thermal conductive gel.

[0112] Comparative Example 3

[0113] Take 1200 parts of iron powder (20 microns 70wt%, 1 micron 30wt%), 67 parts of terminal vinyl methyl cyano silicone oil (viscosity 310cp), 32 parts of terminal hydrogen methyl cyano silicone oil (viscosity 200cp), 0.7 parts of hydrogen-containing silicone oil (viscosity 1000cp), 0.1 parts of acetylene alcohol inhibitor, 0.2 parts of platinum catalyst, mix them thoroughly, mix them with three rollers twice, and degas at room temperature under vacuum for 30 minutes to obtain uncured thermal conductive silicone grease. After transferring it into a mold, cure it at 100°C for 2 hours to obtain a paste-like thermal conductive gel.

[0114] The uncured thermally conductive silicone grease and the cured thermally conductive gel prepared in Examples 1-3 and Comparative Examples 1-3 were tested and analyzed. The effects of the bottle brush modifier on the filler-filled silicone grease and gel system are shown in Table 1.

[0115] Table 1 Effect of modifiers on filler-filled silicone grease and gel systems

[0116]

[0117] It can be seen from the data in Table 1 that, when the metal powder treated with the modifier prepared by the present invention is compared with the metal powder not treated, the viscosity of the silicone grease system after filling is greatly reduced, by about 60-70%, the elongation at break of the silicone gel obtained after vulcanization is greatly increased, and the elongation at break is more than 200%, the Shore hardness 00 is greatly reduced, both below 40, and the thermal conductivity is increased.

[0118] It can be seen that the modifier prepared by the present invention can take into account the good processing technology, high thermal conductivity and softness of the filled silicone gel at the same time, greatly improving the competitiveness of silicone thermal conductive products, and can be widely used in electronic components, communication base stations, new energy batteries, charging piles and other electronic thermal conductive packaging fields.

[0119] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, 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 powder surface modifier, characterized in that: The modifier has the structural formula shown in Formula I: In Formula I, R1 is selected from C 1-10 Alkyl, C 2-10 Any of alkenyl; R2, R3, R4, R5 are the same or different and are independently selected from H, C 1-10 Alkyl, C 2-10 Alkenyl, C 6-14 Aryl, one or more R s Substituted C 1-10 Any of the alkyl groups, wherein R s Any one selected from halogen and cyano; R6 are the same or different and are independently selected from alkyl groups; x is selected from a natural number between 10 and 200, y is selected from a natural number between 1 and 10, and z is selected from a natural number between 10 and 200.

2. A method for preparing the powder surface modifier according to claim 1, characterized in that: The preparation method comprises the following steps: 1) mixing aminopropyltrialkoxysilane, 5-norbornene 2-carboxylic acid, a first solvent and a first catalyst in a certain proportion, and reacting at room temperature for a period of time to obtain a condensate of aminopropyltrialkoxysilane-norbornene; 2) mixing the single-end hydroxyl polysiloxane, 5-norbornene 2-carboxylic acid, a second solvent, a second catalyst, and a dehydrating agent in a certain proportion and reacting them at room temperature for a period of time, adding two times the volume of methanol or ethanol for separation, taking the clear liquid, and vacuum-evacuating the residual solvent to obtain the single-end norbornene functionalized polysiloxane; 3) In an anhydrous and oxygen-free environment, the single-end norbornene functionalized polysiloxane in step 2), the third solvent, and the third catalyst are uniformly mixed in a certain proportion, and after pre-reaction at room temperature for a period of time, a certain amount of aminopropyltrialkoxysilane-norbornene condensate in step 1) is added to continue to react at room temperature for a period of time, and the solvent is removed in vacuo to obtain the powder surface modifier.

3. The preparation method according to claim 2, characterized in that: The first catalyst and the second catalyst are the same or different and are independently selected from any one or more of dimethylaminopyridine and pyrrolidinopyridine; And / or, the third catalyst is selected from ruthenium coordination catalysts.

4. The preparation method according to claim 2 or 3, characterized in that: In step 1), the mass ratio of the aminopropyltrialkoxysilane, 5-norbornene 2-carboxylic acid, the first solvent, and the first catalyst is (40-60):(20-40):(40-60):(0.5-1.5); And / or, the mass ratio of the mono-hydroxylated polysiloxane, 5-norbornene 2-carboxylic acid, the second solvent, the second catalyst, and the dehydrating agent in step 2) is (5-12):(0.2-0.8):(25-35):(0.01-0.04):(1-3); And / or, in step 3), the usage ratio of the single-end norbornene functionalized polysiloxane, the third solvent, the third catalyst, and the silane coupling agent-norbornene condensate is (4-6) g:(40-60) g:(0.0001-0.02) g:(0.05-0.2) g.

5. A modified powder, comprising a powder and the powder surface modifier according to claim 1 located on the surface of the powder.

6. The modified powder according to claim 5, characterized in that: The powder surface modifier is bonded to the surface of the powder in the form of chemical bonds; And / or, the powder is thermally conductive powder.

7. Use of the modified powder according to claim 5 or 6, characterized in that: The modified powder is used in the fields of heat conduction, electricity conduction or electromagnetic shielding.

8. The method for preparing the modified powder according to claim 5 or 6, characterized in that: The preparation method comprises the following steps: The powder surface modifier, powder, fourth solvent and fourth catalyst are uniformly mixed in a certain proportion, fully reacted at a certain temperature for a period of time, condensed and refluxed, filtered, and vacuum dried to obtain the modified powder.

9. A thermally conductive gel, characterized in that: The thermally conductive gel comprises the modified powder according to claim 5 or 6.

10. The method for preparing the thermally conductive gel according to claim 9, characterized in that: The method comprises the following steps: The modified powder is mixed with the raw material for forming the polysiloxane matrix in a certain proportion, kneaded, and cured to obtain the thermal conductive gel.

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