Crystalline copolymer type heat conduction material as well as preparation method and application thereof

Abstract

The invention relates to a crystalline copolymer type heat conduction material as well as a preparation method and application thereof. The thermally conductive material comprises: an epoxy-side chain crystalline acrylate polymer matrix; the epoxy-side chain crystalline acrylate polymer matrix is filled with the heat conducting filler.

Description

Technical Field

[0001] The present invention belongs to the field of composite materials, and particularly relates to a heat-conducting material of a crystalline copolymer type, a preparation method thereof, and an application thereof. Background Art

[0002] With the increasing chip integration and power, the heat dissipation problem has become an important factor restricting its development. Therefore, the industry pays more and more attention to the heat-conducting and heat-dissipating performance of electronic packaging materials. Electronic packaging materials can generally be divided into ceramic packaging and plastic packaging. Ceramic packaging has the highest reliability, but its cost is relatively high. Most civilian chips still mainly adopt the plastic packaging method at present.

[0003] Plastic packaging usually uses epoxy resin as the matrix at present, and is prepared into molding compounds, adhesives and other materials by cooperating with curing agents, fillers and additives for use. The intrinsic thermal conductivity of conventional epoxy resin is generally <0.3 W / m·K, and it is difficult to meet the current heat-conducting requirements when used directly. Usually, a large amount of inorganic heat-conducting fillers need to be dispersed therein to improve its thermal conductivity.

[0004] The heat-conducting principle of polymer-based heat-conducting packaging materials is generally that after a large amount of heat-conducting fillers reach the threshold value, a heat-conducting path is formed to conduct and dissipate heat. Therefore, how to more efficiently construct a heat-conducting network is an important way to solve the current dilemma. Usually, the conventional method for preparing heat-conducting materials requires filling a large amount of heat-conducting fillers in a polymer matrix. However, the distribution of these heat-conducting fillers and the construction of the heat-conducting path are often disordered and uncontrollable, and it is easy to reach the heat-conducting upper limit of such a method only by filling heat-conducting fillers. Summary of the Invention

[0005] Aiming at the above technical problems, the purpose of the present invention is to provide a heat-conducting material of a crystalline copolymer type, a preparation method thereof, and an application thereof that can overcome the above problems. During the polymerization crystallization process of the polymer matrix in the heat-conducting material, the construction of the heat-conducting path of the heat-conducting filler becomes orderly, controllable and efficient, so as to achieve higher thermal conductivity.

[0006] The first aspect of the present invention provides a heat-conducting material of a crystalline copolymer type, and the heat-conducting material of the crystalline copolymer type includes: an epoxy-side chain crystalline acrylate polymer matrix; and a heat-conducting filler filled in the epoxy-side chain crystalline acrylate polymer matrix.

[0007] Preferably, the epoxy-side chain crystalline acrylate polymer matrix is obtained by polymerizing epoxy resin and crystalline acrylate. The "crystalline acrylate" herein refers to those acrylates that can be converted into side chain crystalline acrylate during the polymerization with epoxy resin.

[0008] Preferably, the epoxy resin is selected from at least one or a combination of bisphenol A epoxy resin, bisphenol F epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, phenolic epoxy resin, alicyclic epoxy resin, and is preferably bisphenol A epoxy resin. Among them, bisphenol A epoxy has moderate viscosity, which is conducive to the filling of fillers; and it has a relatively high Tg and excellent reactivity, which is conducive to the formation of materials with good mechanical and thermal conductivity.

[0009] Preferably, the crystalline acrylate is an acrylate containing a long-chain alkyl group with ≥16 carbon atoms, and is preferably selected from at least one or a combination of hexadecyl acrylate (HA), octadecyl acrylate (SA), eicosyl acrylate (IA), docosyl acrylate (DA), octacosyl acrylate (OA), and more preferably octadecyl acrylate and / or docosyl acrylate.

[0010] In the present invention, an epoxy resin and a crystalline acrylate are selected for polymerization reaction. The crystallization of the side chains of the polymerized crystalline acrylate causes the aggregation of the thermal conductive filler, thereby efficiently forming a thermal conductive path, and finally obtaining a crystalline copolymer type thermal conductive material with better thermal conductivity.

[0011] Preferably, the mass ratio of the epoxy resin to the crystalline acrylate is (0.2 - 4):1, preferably (1.4 - 4):1, and more preferably (3 - 4):1.

[0012] Preferably, the epoxy equivalent of the epoxy resin is 170 - 184.

[0013] Preferably, based on the total mass of the thermal conductive material being 100 wt%, the content of the thermal conductive filler is 40 - 95 wt%, preferably 75 - 95 wt%.

[0014] Preferably, the thermal conductive filler is an inorganic filler, and the inorganic filler is selected from at least one or a combination of boron nitride, alumina, aluminum nitride, zinc oxide, quartz, diatomaceous earth, kaolin, aluminum hydroxide, calcium carbonate;

[0015] and / or, the shape of the thermal conductive filler is spherical, quasi-spherical, angular or rod-shaped;

[0016] and / or, the particle size distribution D 50 of the thermal conductive filler is 0.1 μm - 150 μm, preferably 1 μm - 50 μm.

[0017] Preferably, the thermal conductive material satisfies one or more of the following characteristics:

[0018] The viscosity of the thermal conductive material measured according to the ASTM-D445 standard is 14900 - 167000 mPa·s, preferably 14900 - 88000 mPa·s;

[0019] The thermal conductivity of the thermal conductive material measured according to ASTM-D5470 standard is at least 0.98 W / m·K, preferably at least 2.03 W / m·K, more preferably at least 2.97 W / m·K or more;

[0020] The tensile strength of the thermal conductive material measured according to ASTM-D412 standard is 4.0 - 23.0 MPa, preferably 15 - 23.0 MPa;

[0021] The shear strength of the thermal conductive material measured according to ASTM-D1002 standard is 2.8 - 17.0 MPa, preferably 10.0 - 17.0 MPa;

[0022] The hardness of the thermal conductive material measured according to ASTM-D785 standard is 48 - 85 HD, preferably 70 - 85 HD.

[0023] The second aspect of the present invention provides a preparation method of a crystalline copolymer type thermal conductive material, and the preparation method includes the following steps:

[0024] (1) Mix epoxy resin and non-anhydride epoxy curing agent to obtain component A;

[0025] (2) Mix crystalline acrylate, free radical initiator and inhibitor to obtain component B;

[0026] (3) Mix and disperse component A and thermal conductive filler to obtain component A1 containing thermal conductive filler;

[0027] (4) Mix and disperse component B and thermal conductive filler to obtain component B1 containing thermal conductive filler;

[0028] (5) Mix component A1 containing thermal conductive filler and component B1 containing thermal conductive filler, and then cure to obtain a crystalline copolymer type thermal conductive material.

[0029] The present invention utilizes the crystallization characteristics of long-chain alkyl (the number of carbon atoms ≥ 16) in crystalline acrylate. By using component A containing epoxy resin and component B containing crystalline acrylate with specific compositions, the reaction rates of epoxy resin and crystalline acrylic resin are regulated to be basically the same, thereby preparing an epoxy-side chain crystalline acrylate polymer matrix with uniform composition. In this matrix, the side chains of crystalline acrylate crystallize, and these crystal regions aggregate and spontaneously "stack" the thermal conductive fillers together, thus efficiently forming a thermal conductive path. Finally, a material with a very high thermal conductivity can be obtained on the basis of filling the same content of thermal conductive filler.

[0030] Preferably, component A contains 100 parts by weight of epoxy resin, 6 - 13 parts by weight of non-anhydride epoxy curing agent; and / or

[0031] Component B contains 100 parts by weight of crystalline acrylate, 1 to 5 parts by weight of free radical initiator, and 0.04 to 0.2 parts by weight of polymerization inhibitor.

[0032] Preferably, the epoxy resin in Component A is selected from at least one or a combination of bisphenol A epoxy resin, bisphenol F epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, phenolic epoxy resin, alicyclic epoxy resin, and is preferably bisphenol A epoxy resin; and / or

[0033] The non-anhydride epoxy curing agent in Component A is selected from at least one or a combination of amine curing agents, polythiol curing agents, and imidazole curing agents.

[0034] Preferably, the amine curing agent is selected from at least one or a combination of aliphatic amines, alicyclic amines, aromatic amines, and polyamides, and is preferably aminoethyl piperazine; and / or

[0035] The polythiol curing agent is polythiol; and / or

[0036] The imidazole curing agent is imidazole.

[0037] Preferably, the amine curing agent is a tertiary amine.

[0038] Preferably, the crystalline acrylate in Component B is an acrylate containing a long-chain alkyl group with ≥16 carbon atoms, and is preferably selected from at least one or a combination of hexadecyl acrylate (HA), octadecyl acrylate (SA), eicosyl acrylate (IA), docosyl acrylate (DA), octacosyl acrylate (OA), and is more preferably octadecyl acrylate and / or docosyl acrylate; and / or

[0039] The free radical initiator in Component B is selected from at least one or a combination of tert-butyl peroxy-2-ethylhexanoate, benzoyl peroxide, lauroyl peroxide, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, cumene hydroperoxide, and azobisisobutyronitrile, and is preferably tert-butyl peroxy-2-ethylhexanoate; and / or

[0040] The polymerization inhibitor in Component B is selected from at least one or a combination of hydroquinone, p-tert-butylcatechol, 2,6-di-tert-butyl-p-cresol, and hydroquinone.

[0041] Preferably, the preparation method satisfies one or more of the following;

[0042] In step (3), the mixing and dispersion of Component A and the heat-conducting filler are carried out at a temperature of 15 to 35 °C with stirring, wherein the stirring speed is 800 to 1200 r / min and the stirring time is 20 to 30 minutes;

[0043] In step (3), after component A and the heat-conducting filler are mixed and dispersed, they are placed in a three-roll mill for grinding, wherein the roll spacing of the three-roll mill is 0.1 - 0.3 mm;

[0044] In step (4), the mixing and dispersion of component B and the heat-conducting filler are carried out at a temperature of 15 - 35 °C with stirring, wherein the stirring speed is 800 - 1200 r / min, and the stirring time is 20 - 30 minutes;

[0045] In step (4), after component B and the heat-conducting filler are mixed and dispersed, they are placed in a three-roll mill for grinding, wherein the roll spacing of the three-roll mill is 0.1 - 0.3 mm;

[0046] In step (5), the component A1 containing the heat-conducting filler and the component B1 containing the heat-conducting filler are mixed at a mass ratio of (20 - 80):(80 - 20), preferably (60 - 80):(40 - 20), wherein the mass percentage content of the heat-conducting filler in the component A1 containing the heat-conducting filler and the component B1 containing the heat-conducting filler is the same, preferably the content of the heat-conducting filler is 40 - 95 wt%, more preferably 75 - 95 wt%;

[0047] In step (5), the mixing is carried out with stirring, wherein the stirring speed is 100 - 300 r / min, and the stirring time is 1 - 3 minutes;

[0048] In step (5), the curing is thermal curing; the temperature of the thermal curing is 25 °C - 80 °C, and the time is 2 - 48 h.

[0049] The third aspect of the present invention provides an application of the above-mentioned crystalline copolymer-based thermal conductive material in the field of electronic packaging, such as being used as a thermal conductive adhesive in electronic packaging.

[0050] Advantages of the present invention:

[0051] The present invention conducts a unique design and modification on the polymer matrix, enabling it to "assist" the heat-conducting filler to efficiently construct a heat-conducting path during the polymerization / crystallization process, thereby achieving more efficient heat dissipation.

[0052] The present invention uses component A and component B with specific compositions in combination with the heat-conducting filler, controls the reaction rates of the epoxy resin and the crystalline acrylate to be basically the same, and the prepared crystalline copolymer-based thermal conductive material realizes a significant improvement in at least one of the properties of viscosity, thermal conductivity, tensile strength, shear strength, and hardness. Description of the drawings

[0053] Figure 1 Microscopic structure diagram of the thermal conductive material prepared in Example 1. Detailed Embodiments

[0054] The present invention will be further described and explained in conjunction with the following detailed embodiments, which should not be construed as any limitation on the protection scope of the present invention.

[0055] In the present disclosure, the crystalline copolymer-based thermal conductive material comprises: an epoxy-side chain crystalline acrylate polymer matrix, and a thermal conductive filler filled in the epoxy-side chain crystalline acrylate polymer matrix.

[0056] In one embodiment of the present invention, based on the total mass of the crystalline copolymer-based thermal conductive material being 100 wt%, the content of the thermal conductive filler is 40 - 95 wt% (for example, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, etc.), preferably 75 - 95 wt%.

[0057] In one embodiment of the present invention, based on the total mass of the crystalline copolymer-based thermal conductive material being 100 wt%, the content of the epoxy-crystalline acrylate polymer matrix is 5 - 60 wt% (for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, etc.), preferably 5 - 25 wt%.

[0058] In one embodiment of the present invention, the epoxy-crystalline acrylate polymer matrix is obtained by polymerizing an epoxy resin and a crystalline acrylate. In the present invention, a side chain crystalline acrylate is introduced as a crystalline polymer through a copolymerization method, enabling the material to efficiently construct a thermal conduction path through side chain crystallization in combination with the thermal conductive filler.

[0059] In one embodiment of the present invention, the epoxy resin is selected from at least one or a combination of bisphenol A epoxy resin, bisphenol F epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, phenolic epoxy resin, alicyclic epoxy resin, and is preferably bisphenol A epoxy resin. Preferably, the epoxy equivalent of the epoxy resin is 170 - 184.

[0060] In one embodiment of the present invention, the crystalline acrylate is a long-chain alkyl acrylate (the number of carbon atoms in the long-chain alkyl is ≥16), preferably including at least one or a combination of hexadecyl acrylate (HA), octadecyl acrylate (SA), eicosyl acrylate (IA), docosyl acrylate (DA), octacosyl acrylate (OA), and is more preferably octadecyl acrylate and / or docosyl acrylate. Among the easily obtainable long-chain alkyl acrylate esters, octadecyl and docosyl acrylate esters have the best crystallization performance.

[0061] In one embodiment of the present invention, the mass ratio of the epoxy resin to the crystalline acrylate is (0.2 - 4):1 (such as 0.2:1, 0.5:1, 1.0:1, 1.5:1, 2.0:1, 2.5:1, 3.0:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 4.0:1, etc.), preferably (1.4 - 4):1, and more preferably (3 - 4):1. For example, when the crystalline acrylate is stearyl acrylate (SA), the mass ratio of the epoxy resin to the crystalline acrylate is (3 - 4):1, preferably (3.5 - 4:1). When the crystalline acrylate is docosyl acrylate (DA), the mass ratio of the epoxy resin to the crystalline acrylate is (1.4 - 4):1, preferably (3 - 4):1, and more preferably (3.5 - 4:1).

[0062] In one embodiment of the present invention, the epoxy-side chain crystalline acrylate polymer matrix is obtained by polymerizing component A and component B. Component A includes an epoxy resin and a non-anhydride epoxy curing agent, and component B includes a crystalline acrylate, a radical initiator, and a polymerization inhibitor. The non-anhydride epoxy curing agent (preferably an amine curing agent) used in the present invention has a fast curing rate, maintains a small difference in the curing rates of the crystalline acrylate part and the epoxy resin part, avoids phase separation, and ultimately makes the obtained epoxy-side chain crystalline acrylate polymer matrix have a uniform composition.

[0063] In one embodiment of the present invention, component A includes 100 parts by weight of an epoxy resin and 6 - 13 parts by weight of a non-anhydride epoxy curing agent. Among them, the non-anhydride epoxy curing agent is selected from at least one or a combination of amine curing agents, polythiol curing agents, and imidazole curing agents. Preferably, the amine curing agent is selected from at least one or a combination of aliphatic amines, cycloaliphatic amines, aromatic amines, and polyamides. Preferably, the amine curing agent is a tertiary amine, where the tertiary amine catalyzes the self-polymerization of the epoxy resin, and other amine curing agents can participate in epoxy curing with different mechanisms. Preferably, it is aminoethyl piperazine. Preferably, the polythiol curing agent is polythiol. Preferably, the imidazole curing agent is imidazole.

[0064] In one embodiment of the present invention, the epoxy resin and the non-anhydride epoxy curing agent are mixed to prepare component A. Among them, the mixing method is stirring, the stirring speed is set to 500 - 800 r / min, and the stirring time is 15 - 20 minutes.

[0065] In an embodiment of the present invention, component A and a thermal conductive filler are mixed and dispersed to obtain component A1 containing the thermal conductive filler. Wherein, the content of the thermal conductive filler in the component A1 containing the thermal conductive filler is 40-95 wt% (for example, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, etc.), preferably 75-95 wt%. The mixing and dispersion are carried out at a temperature of 15-35 °C with stirring, wherein the stirring speed is 800-1200 r / min and the stirring time is 20-30 minutes. In a preferred embodiment, after component A and the thermal conductive filler are mixed and dispersed, they are placed in a three-roll mill for grinding, wherein the roll spacing of the three-roll mill is 0.1-0.3 mm, and the purpose of this step is to further disperse the thermal conductive filler.

[0066] In an embodiment of the present invention, component B comprises 100 parts by weight of a crystalline acrylate, 1-5 parts by weight of a radical initiator, and 0.04-0.2 parts by weight of a polymerization inhibitor. The radical initiator in component B is selected from at least one or a combination of tert-butyl peroxy-2-ethylhexanoate, benzoyl peroxide, lauroyl peroxide, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, cumene hydroperoxide, azobisisobutyronitrile, etc., preferably tert-butyl peroxy-2-ethylhexanoate. The polymerization inhibitor in component B is selected from at least one or a combination of hydroquinone, p-tert-butylcatechol, 2,6-di-tert-butyl-p-cresol, hydroquinone, etc.

[0067] In an embodiment of the present invention, the crystalline acrylate, the radical initiator, and the polymerization inhibitor are mixed to obtain component B. The mixing method can be stirring, setting the stirring speed at 600-900 r / min, and stirring for 10-15 minutes to make them fully mixed and uniform to form component B (or acrylate premix).

[0068] In an embodiment of the present invention, component B and a heat-conducting filler are mixed and dispersed to obtain component B1 containing the heat-conducting filler. Among them, the content of the heat-conducting filler in the component B1 containing the heat-conducting filler is 40-95 wt% (for example, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, etc.), preferably 75-95 wt%. Preferably, the content of the heat-conducting filler in the component A1 containing the heat-conducting filler and the component B1 containing the heat-conducting filler is the same. The mixing and dispersion are carried out at a temperature of 15-35 °C with stirring, wherein the stirring speed is 800-1200 r / min and the stirring time is 20-30 minutes. In a preferred embodiment, after component B and the heat-conducting filler are mixed and dispersed, they are placed in a three-roll mill for grinding, wherein the roll spacing of the three-roll mill is 0.1-0.3 mm, and the purpose of this step is to further disperse the heat-conducting filler.

[0069] In an embodiment of the present invention, after the component A1 containing the heat-conducting filler and the component B1 containing the heat-conducting filler are mixed, they are cured (for example, thermally cured) to obtain the heat-conducting material. Among them, the component A1 containing the heat-conducting filler and the component B1 containing the heat-conducting filler are mixed in a mass ratio of (20-80):(80-20) (for example, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, etc.), preferably (60-80):(40-20). Among them, the mixing is carried out with stirring, wherein the stirring speed is 100-300 r / min and the stirring time is 1-3 minutes. The temperature of the thermal curing is 25 °C to 80 °C and the time is 2-48 h (for example, 80 °C / 2 h, 25 °C / 48 h).

[0070] In a preferred embodiment of the present invention, the heat-conducting filler is an inorganic filler, and the heat-conducting filler is selected from at least one or a combination of boron nitride, aluminum oxide, aluminum nitride, zinc oxide, quartz, diatomaceous earth, kaolin, aluminum hydroxide, calcium carbonate, etc.

[0071] In a preferred embodiment of the present invention, the shape of the heat-conducting filler is spherical, quasi-spherical, angular or rod-shaped.

[0072] In a preferred embodiment of the present invention, the particle size distribution D of the heat-conducting filler 50 is 0.1 μm to 150 μm (for example, 0.1 μm, 1 μm, 5 μm, 15 μm, 25 μm, 50 μm, 75 μm, 100 μm, 125 μm, 150 μm, etc.), preferably 1 μm to 50 μm, and more preferably 5-15 μm.

[0073] Characteristic test standard:

[0074] The viscosity of the heat-conducting material of the crystalline copolymer type measured according to ASTM-D445 standard;

[0075] The thermal conductivity of the heat-conducting material of the crystalline copolymer type measured according to ASTM-D5470 standard;

[0076] The tensile strength of the heat-conducting material of the crystalline copolymer type measured according to ASTM-D412 standard;

[0077] The shear strength of the heat-conducting material of the crystalline copolymer type measured according to ASTM-D1002 standard;

[0078] The hardness of the heat-conducting material of the crystalline copolymer type measured according to ASTM-D785 standard.

[0079] The raw materials used in the following examples and comparative examples are shown in Table 1 or Table 3, where:

[0080] Bisphenol A epoxy resin: The manufacturer is Dow Chemical, and the model is DER-331,

[0081] Bisphenol F epoxy resin: The manufacturer is Nan Ya Plastics, and the model is NPEF-170,

[0082] Biphenyl-type epoxy resin: The manufacturer is Mitsubishi Chemical, and the model is YX4000,

[0083] Naphthalene-type epoxy resin: The manufacturer is Shanghai Huayi Resin, and the model is EBA-65,

[0084] Phenolic epoxy resin: The manufacturer is Dow Chemical, and the model is DEN438,

[0085] Alicyclic epoxy resin: The manufacturer is Daicel, and the model is 2021P.

[0086] Examples 1-21 (E1-E21) and Comparative Examples 1-9 (CE1-CE9)

[0087] (1) Preparation of epoxy premix:

[0088] Weigh 100 g of bisphenol A epoxy resin and 10 g of aminoethylpiperazine (AEP) curing agent, then add the weighed raw materials into a blender, set the stirring speed to 500-800 r / min, and the stirring time to 15-20 minutes, and mix thoroughly until evenly mixed to prepare an epoxy premix (i.e., component A).

[0089] (2) Preparation of long-chain alkyl acrylate premix:

[0090] Weigh 100 g of long-chain alkyl acrylate (stearyl acrylate (SA), docosyl acrylate (DA), or lauryl acrylate (LA)), 3 g of tert-butyl peroxy-2-ethylhexanoate (OT) free radical initiator, and 0.2 g of hydroquinone inhibitor. Then pour the weighed raw materials into a double planetary defoamer, heat up to 40 °C, set the stirring speed to 600 - 900 r / min, and stir for 10 - 15 minutes to make them fully and evenly mixed, thus preparing an acrylate premix.

[0091] (3) Preparation of component A1 containing a heat-conducting filler:

[0092] Mix and disperse component A and a heat-conducting filler (spherical alumina, D 50 = 5 μm) according to the mass percentage content (40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, or 90 wt%), and then place it in a three-roll mill for grinding to obtain component A1 containing a heat-conducting filler. Among them, it is carried out at a temperature of 15 - 35 °C with stirring, where the stirring speed is 800 - 1200 r / min and the stirring time is 20 - 30 minutes. The roll spacing of the three-roll mill is 50 μm.

[0093] (4) Preparation of component B1 containing a heat-conducting filler:

[0094] Mix and disperse component B and a heat-conducting filler (spherical alumina, D 50 = 5 μm) (carried out at a temperature of 15 - 35 °C with stirring, the stirring speed is 800 - 1200 r / min, and the stirring time is 20 - 30 minutes), and then place it in a three-roll mill for grinding, where the roll spacing of the three-roll mill is 50 μm, to obtain component B1 containing a heat-conducting filler, and the mass percentage content of its heat-conducting filler is the same as that of component A1 containing a heat-conducting filler.

[0095] (5) Preparation of heat-conducting material:

[0096] Weigh component A1 containing a heat-conducting filler and component B1 containing a heat-conducting filler according to a predetermined mass ratio (100 g / 0 g, 0 g / 100 g, 80 g / 20 g, 60 g / 40 g, 50 g / 50 g, 40 g / 60 g, 20 g / 80 g) and mix (the stirring speed is 100 - 300 r / min, and the stirring time is 1 - 3 minutes), and then carry out heat curing (120 °C, 1 h) to finally obtain a heat-conducting material, and its performance parameters are shown in Table 2.

[0097] Table 1

[0098]

[0099]

[0100] Table 2

[0101]

[0102]

[0103] Figure 1 Microstructure diagram of the thermal conductive material prepared for Example 1. It can be seen from the figure that the composition of the obtained thermal conductive material is uniform. The spherical structure is crystalline acrylate, which shows birefringence under a polarized light microscope, and the gray flat area is epoxy structure.

[0104] For the thermal conductive material of the present invention, on the basis of a higher thermal conductivity, generally the lower the viscosity, the better; the higher the tensile strength, the better; the higher the shear strength, the better; the hardness > 45 HD, preferably > 60 HD, more preferably > 70 HD is sufficient.

[0105] Comparing Comparative Example 1, Examples 1-5 and Comparative Example 2, it can be seen that with the change of the mass ratio of Component A and Component B, at least one of the viscosity, thermal conductivity, tensile strength, shear strength and hardness of the thermal conductive materials obtained in Examples 1-5 is significantly improved. Especially, the comprehensive performance of the composite material obtained in Example 1 is the best.

[0106] Comparing Examples 1-10 and Comparative Examples 7-11, it can be seen that LA is similar in structure to SA / DA, but LA does not belong to crystalline acrylate. From the results, it can be seen that when the mass ratio of Component A and Component B is 80 / 20, the thermal conductivity of the thermal conductive material prepared by SA / DA is better than that of the thermal conductive material prepared by LA. When the mass ratio of Component A and Component B is 60-50:40-50, only the thermal conductivity of the thermal conductive material prepared by DA is better than that of LA. When the mass ratio of Component A and Component B is (40-20):(60-80), the thermal conductivity of the thermal conductive materials prepared by SA / DA is inferior to that of the thermal conductive materials prepared by LA. Among them, when the mass ratio of epoxy / SA acrylate is 80 / 20, the best comprehensive performance is obtained.

[0107] Comparing Examples 1, 6, 14-16, it can be seen that selecting different types of crystalline acrylates can all achieve a significant improvement in at least one of the viscosity, thermal conductivity, tensile strength, shear strength and hardness of the obtained thermal conductive materials. Especially, the comprehensive performance of the thermal conductive material obtained in Example 1 is the best.

[0108] Comparing Examples 11-12, Example 1 and Example 13, it can be seen that with the increase of the mass content of the thermal conductive filler, its thermal conductivity gradually increases, but the viscosity also increases accordingly, and the operability becomes poor. Especially, the comprehensive performance of Example 1 is the best.

[0109] Comparing Examples 1, 17 - 21, it can be seen that selecting different types of epoxy resins can all achieve a significant improvement in at least one of the viscosity, thermal conductivity, tensile strength, shear strength, and hardness of the resulting thermal conductive material. In particular, the comprehensive performance of the thermal conductive material obtained in Example 1 is the best.

[0110] Examples 22 - 25 (E22 - E25) and Comparative Examples 12 - 16 (CE12 - CE16)

[0111] Prepare Component A and Component B according to the formula in Table 3. The preparation steps and parameters of other thermal conductive materials are the same as those in Example 1, where the mass ratio of Component A1 containing the thermal conductive filler to Component B1 containing the thermal conductive filler is 80 / 20, and the content of the thermal conductive filler is 80 wt%. The performance parameters of the resulting thermal conductive material are shown in Table 4.

[0112] Table 3 (units of each component are g)

[0113]

[0114] Table 4

[0115]

[0116] Comparing Example 22 (E22), Example 1 (E1), and Example 23 (E23), it can be seen that with the increase in the addition amount of the non - anhydride curing agent, at least one of the viscosity, thermal conductivity, tensile strength, shear strength, and hardness of the resulting thermal conductive material is significantly improved. However, when a small amount of the non - anhydride curing agent is added in Comparative Example 12 (CE12), the curing rate and the final curing conversion rate of the epoxy part are reduced, ultimately resulting in a decrease in thermal conductivity, tensile strength, shear strength, and hardness, especially tensile strength and shear strength. However, when an excessive amount of the non - anhydride curing agent is added in Comparative Example 13 (CE13), the excessive curing agent cannot participate in the reaction and acts as a plasticizer, thus leading to a decrease in thermal conductivity, tensile strength, shear strength, and hardness, especially shear strength.

[0117] Comparing Example 24 (E24), Example 1 (E1), and Example 25 (E25), it can be seen that with the increase in the addition amount of the non - anhydride curing agent, at least one of the viscosity, thermal conductivity, tensile strength, shear strength, and hardness of the resulting thermal conductive material is significantly improved. However, when a small amount of the initiator is added in Comparative Example 14 (CE14), the curing rate and the curing conversion rate of the acrylate component are reduced, ultimately resulting in a decrease in thermal conductivity, tensile strength, shear strength, and hardness, especially shear strength. However, when an excessive amount of the initiator is added in Comparative Example 15 (CE15), the final molecular weight of the acrylate component is too low, and it also leads to a decrease in thermal conductivity, tensile strength, shear strength, and hardness, especially shear strength.

[0118] Comparing Comparative Example 16 (CE16) with Example 1 (E1), since no polymerization inhibitor was added in Comparative Example 16, partial polymerization reaction of the crystalline acrylate occurred prematurely during the preparation of the acrylate premix and Component B containing the heat-conducting filler, and partial gelation occurred during the mixing with Component A containing the heat-conducting filler. The two components were not uniform, and finally the thermal conductivity, tensile strength, shear strength and hardness of the obtained thermal conductive material all decreased.

[0119] In summary, by controlling the polymerization rates of the epoxy resin and the crystalline acrylic resin to be basically the same, the present invention regulates the aggregation of the heat-conducting filler and forms a heat-conducting path while forming a uniform epoxy-side chain crystalline acrylate polymer matrix, thereby significantly affecting performance parameters such as viscosity, thermal conductivity, tensile strength, shear strength and hardness. It should be noted that the significant influence of the epoxy-side chain crystalline acrylate polymer matrix on the thermal conductivity in the present invention mainly refers to: on the premise that the heat-conducting filler is fixed, by regulating the polymer matrix formed by different types and content ratios of epoxy resin / crystalline acrylic resin, the thermal conductivity of the thermal conductive material is adjusted. In the present invention, the main factors that have a significant influence on the thermal conductivity of the thermal conductive material are still the different selections of at least one or a combination of the composition, shape and particle size of the heat-conducting filler. Although such different selections have little influence on the viscosity, tensile strength, shear strength and hardness of the thermal conductive material. Taking spherical alumina as the filler as an example, the present invention can, through the regulation of a polymer matrix with a specific composition, achieve a thermal conductivity of the thermal conductive material measured according to ASTM-D5470 standard of 0.98 - 4.52 W / m·K (preferably 2.03 - 4.52 W / m·K), but this does not mean that the thermal conductivity of the thermal conductive material in the present invention is limited between 0.98 - 4.52 W / m·K. Although the present invention does not show examples of other different heat-conducting fillers, those skilled in the art can completely, through the conventional selection of at least one or a combination of the composition, shape and particle size of the heat-conducting filler disclosed in the present invention, without changing the composition of the polymer matrix of the present invention, prepare a thermal conductive material with a higher thermal conductivity (for example, reaching above 5 W / m·K, preferably reaching above 6 W / m·K, and even reaching above 8 W / m·K), which should be regarded as various modifications and changes that can be made to the present invention without departing from the scope of the present invention.

[0120] It should be noted that all the technical features described in this application can be freely combined or integrated in any way, unless contradictions arise between them. Various modifications and variations can be made to the present invention without departing from its scope, which will be obvious to those skilled in the art. For example, features shown or described as part of one embodiment can be used with another embodiment to yield yet another embodiment. Accordingly, the present invention is intended to cover such modifications and variations that fall within the scope of the appended claims and their equivalents.

Claims

1. A thermally conductive material, characterized in that: The thermally conductive material comprises: Epoxy-side chain crystalline acrylate polymer matrix; and A thermally conductive filler is filled in the epoxy-side chain crystalline acrylate polymer matrix.

2. The thermally conductive material according to claim 1, characterized in that: The epoxy-side chain crystalline acrylate polymer matrix is ​​obtained by polymerizing epoxy resin and crystalline acrylate; The epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, biphenyl epoxy resin, naphthalene epoxy resin, novolac epoxy resin, alicyclic epoxy resin or a combination thereof, preferably bisphenol A epoxy resin; The crystalline acrylate is an acrylate containing a long-chain alkyl group with a carbon number of ≥16, preferably selected from at least one of hexadecyl acrylate (HA), octadecyl acrylate (SA), eicosyl acrylate (IA), docosyl acrylate (DA), and octadecyl acrylate (OA) or a combination thereof, more preferably octadecyl acrylate and / or docosyl acrylate.

3. The thermally conductive material according to claim 2, characterized in that: The mass ratio of the epoxy resin to the crystalline acrylate is (0.2-4):1, preferably (1.4-4):1, and more preferably (3-4):1; And / or, the epoxy equivalent of the epoxy resin is 170-184.

4. The thermally conductive material according to any one of claims 1 to 3, characterized in that Based on the total mass of the thermally conductive material being 100 wt %, the content of the thermally conductive filler is 40 to 95 wt %, preferably 75 to 95 wt %.

5. The thermally conductive material according to any one of claims 1 to 3, characterized in that: The thermally conductive filler is an inorganic filler, and the inorganic filler is selected from at least one of boron nitride, aluminum oxide, aluminum nitride, zinc oxide, quartz, diatomaceous earth, kaolin, aluminum hydroxide, and calcium carbonate, or a combination thereof; and / or, the shape of the thermally conductive filler is spherical, quasi-spherical, angular or rod-shaped; And / or, the particle size distribution D of the thermally conductive filler 50 It is 0.1 μm to 150 μm, preferably 1 μm to 50 μm.

6. The thermally conductive material according to any one of claims 1 to 3, characterized in that: The thermally conductive material satisfies one or more of the following characteristics: The viscosity of the thermally conductive material measured according to ASTM-D445 standard is 14900-167000 mPa·s, preferably 14900-88000 mPa·s; The thermal conductivity of the thermally conductive material measured according to ASTM-D5470 standard is at least 0.98 W / m·K, preferably at least 2.03 W / m·K, and more preferably at least 2.97 W / m·K; The tensile strength of the thermally conductive material measured according to ASTM-D412 standard is 4.0 to 23.0 MPa, preferably 15 to 23 MPa; The shear strength of the thermally conductive material measured according to ASTM-D1002 standard is 2.8 to 17.0 MPa, preferably 10.0 to 17.0 MPa; The hardness of the thermal conductive material measured according to ASTM-D785 standard is 48 to 85 HD, preferably 70 to 85 HD.

7. A method for preparing a thermally conductive material, characterized in that: The preparation method comprises the following steps: (1) mixing an epoxy resin and a non-anhydride epoxy curing agent to prepare component A; (2) mixing a crystalline acrylate, a free radical initiator and an inhibitor to prepare component B; (3) mixing and dispersing component A and a thermally conductive filler to obtain component A1 containing a thermally conductive filler; (4) mixing and dispersing component B and a thermally conductive filler to obtain component B1 containing a thermally conductive filler; (5) Component A1 containing a thermally conductive filler and component B1 containing a thermally conductive filler are mixed and then cured to obtain the thermally conductive material.

8. The preparation method according to claim 7, characterized in that: The component A comprises 100 parts by weight of epoxy resin and 6 to 13 parts by weight of non-anhydride epoxy curing agent; and / or The component B comprises 100 parts by weight of crystalline acrylate, 1 to 5 parts by weight of a free radical initiator, and 0.04 to 0.2 parts by weight of a polymerization inhibitor.

9. The preparation method according to claim 7, characterized in that: The epoxy resin in component A is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, biphenyl epoxy resin, naphthalene epoxy resin, novolac epoxy resin, alicyclic epoxy resin or a combination thereof, preferably bisphenol A epoxy resin; and / or The non-anhydride epoxy curing agent in component A is selected from at least one of an amine curing agent, a polythiol curing agent, an imidazole curing agent, or a combination thereof; and / or The crystalline acrylate in component B is an acrylate containing a long-chain alkyl group with a carbon number of ≥16, preferably at least one selected from hexadecyl acrylate (HA), octadecyl acrylate (SA), eicosyl acrylate (IA), docosyl acrylate (DA), and octadecyl acrylate (OA) or a combination thereof, more preferably octadecyl acrylate and / or docosyl acrylate; and / or The free radical initiator in component B is selected from at least one of tert-butyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, lauroyl peroxide, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, isopropylbenzene hydroperoxide, and azobisisobutyronitrile, or a combination thereof, preferably tert-butyl peroxy-2-ethylhexanoate; and / or The polymerization inhibitor in the component B is selected from at least one of hydroquinone, p-tert-butylcatechol, 2,6-di-tert-butyl-p-methylphenol, and hydroquinone, or a combination thereof.

10. The preparation method according to claim 9, characterized in that: The amine curing agent is selected from at least one of aliphatic amines, alicyclic amines, aromatic amines, polyamides or a combination thereof, preferably aminoethylpiperazine; and / or The polythiol curing agent is polythiol; and / or The imidazole curing agent is imidazole.

11. The preparation method according to claim 9, characterized in that: The amine curing agent is a tertiary amine.

12. The preparation method according to any one of claims 7 to 11, characterized in that: The preparation method satisfies one or more of the following: In step (3), the mixing and dispersion of component A and the thermally conductive filler is carried out at a temperature of 15 to 35° C. and under stirring, wherein the stirring speed is 800 to 1200 r / min and the stirring time is 20 to 30 minutes; In step (3), component A and the thermally conductive filler are mixed and dispersed and then placed in a three-roll mill for grinding, wherein the roller spacing of the three-roll mill is 0.1 to 0.3 mm; In step (4), the mixing and dispersion of component B and the thermally conductive filler is carried out at a temperature of 15 to 35° C. and under stirring, wherein the stirring speed is 800 to 1200 r / min and the stirring time is 20 to 30 minutes; In step (4), component B and the thermally conductive filler are mixed and dispersed and then placed in a three-roll mill for grinding, wherein the roller spacing of the three-roll mill is 0.1 to 0.3 mm; In step (5), the component A1 containing the thermally conductive filler and the component B1 containing the thermally conductive filler are mixed in a mass ratio of (20-80): (80-20), preferably (60-80): (40-20), wherein the mass percentage of the thermally conductive filler in the component A1 containing the thermally conductive filler and the component B1 containing the thermally conductive filler is the same, preferably the content of the thermally conductive filler is 40-95wt%, more preferably 75-95wt%; In step (5), the mixing is performed under stirring, wherein the stirring speed is 100 to 300 r / min, and the stirring time is 1 to 3 minutes; In step (5), the curing is thermal curing; the temperature of the thermal curing is 25°C to 80°C, and the time is 2 to 48 hours.

13. Use of the thermally conductive material according to any one of claims 1 to 6 in the field of electronic packaging.

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