A black substrate-free mesh exhaust heat-conducting double-sided tape

Abstract

A black substrate-free grid exhaust heat-conducting double-sided tape and its preparation method, comprising a first grid release layer, a heat-conducting adhesive layer and a second grid release layer which are sequentially laminated; the heat-conducting adhesive layer is made of the following raw materials: heat-conducting filler, flame retardant, dispersant, black filler, acrylate-capped hyperbranched organosilicon-modified polyurethane, curing agent, 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt, 4-acryloylhydroxybenzoic acid benzophenone, 2,4,6-trivinylcyclotriboroxane, tris(2-acryloyloxyethyl) isocyanurate, tricyclo[5.2.1.02,6]dec-8-yl methacrylate, 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 2-vinylpyridine, diluent. This double-sided tape has good adhesion, excellent heat-conducting performance, high-temperature resistance and resistance to damp heat aging performance.

Description

Technical Field

[0001] The present invention relates to the technical field of tapes, and particularly to a black substrate-free grid exhaust heat-conducting double-sided tape. Background Art

[0002] With the development of display technology, OLED (organic light-emitting diode) displays are increasingly favored by people. Especially, the use of in-vehicle OLED displays is becoming more and more widespread. However, in daily use, in-vehicle OLED displays are affected by the heat generated during vehicle operation, and their own long-term high-brightness state will also generate high heat. These heats often cannot be conducted out of the OLED display in time, thus accelerating the aging of the organic materials of the OLED device, and then problems such as screen burn-in and uneven picture display occur. It is precisely in this situation that the grid exhaust heat-conducting tape for in-vehicle OLED displays came into being, and its appearance has attracted wide attention in the industry.

[0003] Most of the existing grid exhaust heat-conducting tapes for in-vehicle OLED displays use grid fibers as the tape substrate, and then complete the gluing by a single-sided coating process. The preparation process is relatively complex and the cost is relatively high. At the same time, the grid exhaust heat-conducting tapes for in-vehicle OLED displays on the market still have more or less technical defects such as poor adhesion, insufficient heat-conducting performance, and the need to further improve the high-temperature resistance performance and the resistance to damp heat aging performance.

[0004] In order to solve the above problems, the Chinese invention patent with the authorization announcement number of CN115491135B discloses a high-temperature-resistant grid acrylic pressure-sensitive tape and its preparation method. The grid acrylic pressure-sensitive tape includes a grid release film and a modified acrylic pressure-sensitive adhesive coated on the surface of the grid release film. Among them, the components of the modified acrylic pressure-sensitive adhesive are calculated according to weight parts, including: 20-30 parts of butyl acrylate, 18-24 parts of 2-ethylhexyl acrylate, 15-20 parts of 2-hydroxyethyl acrylate, 6.5-8.8 parts of octaphenylaminepropyl caged polyhedral oligomeric silsesquioxane, 4.2-5.6 parts of acrylamide-modified scandium tungstate powder, 1.2-3.6 parts of initiator, 6-12 parts of the first solvent, and 14-24 parts of the second solvent. The finally obtained grid acrylic pressure-sensitive tape can maintain a relatively high peel strength while having good improvement in the tackiness and high-temperature peel performance of the pressure-sensitive adhesive. However, its resistance to damp heat aging performance and heat conductivity still need to be further improved.

[0005] It can be seen that developing a grid exhaust heat-conducting tape with good adhesion, excellent heat-conducting performance, high-temperature resistance performance and resistance to damp heat aging performance meets the market demand, has broad market value and application prospects, and has very important significance for promoting the development of the tape field for in-vehicle OLED displays. Summary of the Invention

[0006] The object of the present invention is to provide a black substrate-free grid exhaust heat-conducting double-sided tape with good adhesiveness, excellent heat-conducting performance, high-temperature resistance and damp-heat aging resistance, and sufficient light-shielding property and exhaust property of the adhesive surface.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a black substrate-free grid exhaust heat-conducting double-sided tape, which includes a first grid release layer, a heat-conducting adhesive layer and a second grid release layer stacked in sequence; the heat-conducting adhesive layer is made of the following raw materials by weight: 20-50 parts of heat-conducting filler, 0-10 parts of flame retardant, 0.1-1 part of dispersant, 0.1-5 parts of black filler, 20-40 parts of acrylate-capped hyperbranched organosilicon-modified polyurethane, 0.1-1 part of curing agent, 1-3 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt, 1-3 parts of 4-acryloylhydroxybenzoic acid phenyl ketone, 2-4 parts of 2,4,6-trivinylcyclotriboroxane, 0.5-1.5 parts of tris(2-acryloyloxyethyl) isocyanurate, 0.8-1.2 parts of tricyclo[5.2.1.02,6]dec-8-yl methacrylate, 0.3-0.6 parts of 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 1-3 parts of 2-vinylpyridine, and 30-40 parts of diluent.

[0008] Preferably, the heat-conducting filler is any one or more of spherical alumina, hexagonal boron nitride, and aluminum nitride whiskers.

[0009] Preferably, the average particle size of the spherical alumina is 10-30 μm; the hexagonal boron nitride is 1-3 μm; the diameter of the aluminum nitride whiskers is 2-30 μm, and the length is 0.5-3 cm.

[0010] Preferably, the flame retardant is at least one of aluminum hydroxide flame retardant H-WF-10 and magnesium hydroxide flame retardant XS-MHB-3; the dispersant is at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

[0011] Preferably, the black filler is at least one of carbon black, graphite, carbon nanotubes, and graphene; the particle size of the black filler is 1000-1500 mesh.

[0012] Preferably, there is no special requirement for the source of the acrylate-capped hyperbranched organosilicon-modified polyurethane. In an embodiment of the present invention, the acrylate-capped hyperbranched organosilicon-modified polyurethane is prepared by the method of Example 1 in the authorized announcement number CN111393608B.

[0013] Preferably, the curing agent is a mixture of benzoin ethyl ether, azobisisobutyronitrile, and benzoin isopropyl ether in a mass ratio of (1 - 3):(0.8 - 1.2):1.

[0014] Preferably, the diluent is a mixture formed by mixing butyl acrylate, dipropylene glycol diacrylate, and 2-methoxyethyl acrylate in a mass ratio of (1 - 2):1:(1 - 3).

[0015] Preferably, the first grid release layer and the second grid release layer are each independently made of a PET release film with a grid pattern.

[0016] Preferably, the grid walls of the PET release film with a grid pattern are in a convex shape, and its cross-section is one of a trapezoid, a triangle, an inverted U shape, a rectangle, and a hemispherical shape; the width of the grid wall is 4 - 20 μm, the depth of the grid wall is 1 - 3 μm, and the distance between the grid walls is 130 - 210 μm; the included angle at the intersection of the horizontal and vertical grid walls of the PET release film with a grid pattern is 90 - 180°.

[0017] Preferably, the thickness of the thermally conductive adhesive layer is 10 - 150 μm.

[0018] Another object of the present invention is to provide a method for preparing the black substrate-free grid exhaust heat-conducting double-sided tape, comprising the following steps:

[0019] Step S1: Mix and stir the raw materials of the thermally conductive adhesive layer according to parts by weight, disperse them ultrasonically, and evacuate to remove bubbles to obtain the thermally conductive adhesive.

[0020] Step S2: Uniformly coat the thermally conductive adhesive prepared in Step S1 on the first grid release layer, cover the second grid release layer on the thermally conductive adhesive layer, irradiate it under ultraviolet light, and then bake it at 50 - 70 °C for 3 - 6 minutes. After curing, the black substrate-free grid exhaust heat-conducting double-sided tape is obtained.

[0021] Preferably, the wavelength of the ultraviolet light is 300 - 400 nm, and the irradiation time is 3 - 5 min.

[0022] Due to the application of the above technical solutions, the present invention has the following beneficial effects:

[0023] (1) The method for preparing the black substrate-free grid exhaust heat-conducting double-sided tape disclosed by the present invention has a simple process, convenient operation and control, high preparation efficiency and finished product qualification rate, does not require special equipment, has low capital investment, low energy consumption, does not add any organic solvents, avoids the safety hazards of using organic solvents as diluents, reduces the input cost of organic solvents at the same time, has better environmental protection, is suitable for continuous large-scale production, and has high popularization and application value.

[0024] (2) The black substrate-free grid exhaust heat-conducting double-sided tape disclosed by the present invention is provided with a first grid release layer and a second grid release layer, so that gas can be easily discharged when the double-sided tape is attached to the object to be attached, improving the product yield; introducing black fillers greatly improves the overall shielding property of the tape, and can improve the light leakage phenomenon at the edge of the OLED display when applied in the in-vehicle OLED display; adopting a substrate-free structure, due to the absence of the thermal resistance effect of the substrate, the thermal conductivity is higher.

[0025] (3) The black substrate-free grid exhaust heat-conducting double-sided tape disclosed by the present invention, wherein the heat-conducting adhesive layer is made of the following raw materials by weight: 20-50 parts of heat-conducting filler, 0-10 parts of flame retardant, 0.1-1 part of dispersant, 0.1-5 parts of black filler, 20-40 parts of acrylate-capped hyperbranched organosilicon-modified polyurethane, 0.1-1 part of curing agent, 1-3 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt, 1-3 parts of 4-acryloylhydroxybenzoic acid phenyl ketone, 2-4 parts of 2,4,6-trivinylcyclotriboroxane, 0.5-1.5 parts of tris(2-acryloyloxyethyl) isocyanurate, 0.8-1.2 parts of tricyclo[5.2.1.02,6]dec-8-yl methacrylate, 0.3-0.6 parts of 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 1-3 parts of 2-vinylpyridine, 30-40 parts of diluent. Through the reasonable selection of the raw material formula for preparing the heat-conducting adhesive layer, the various raw materials can better cooperate with each other and act together, making the prepared double-sided tape product have good adhesiveness, excellent heat-conducting performance, high-temperature resistance and heat and humidity aging resistance, and sufficient light-shielding property and adhesive surface fitting exhaust property. Through ultraviolet light and heat curing, not only an interpenetrating network structure is formed in the molecular structure of the glue, but also hyperbranched organosilicon-modified polyurethane, zwitterionic organic salt, benzophenone, cyclotriboroxane, isocyanurate, quinoxaline and pyridine groups are introduced at the same time. Under the multiple actions of these structures and groups such as electronic effect, steric effect and conjugation effect, the bonding performance of the product is better, more effective heat bridges are formed, the heat-conducting performance is better, the high-temperature resistance and heat aging resistance are more excellent, and the service life is longer. Detailed Embodiments

[0026] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations.

[0027] Example 1

[0028] A black substrate-free grid exhaust heat-conducting double-sided tape, comprising a first grid release layer, a heat-conducting adhesive layer, and a second grid release layer that are sequentially stacked; the heat-conducting adhesive layer is made of the following raw materials by weight: 20 parts of heat-conducting filler, 1 part of flame retardant, 0.1 part of dispersant, 1 part of black filler, 20 parts of acrylate-capped hyperbranched silicone-modified polyurethane, 0.1 part of curing agent, 1 part of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt, 1 part of 4-acryloylhydroxybenzoic acid phenyl ketone, 2 parts of 2,4,6-trivinylcyclotriboroxane, 0.5 part of tris(2-acryloyloxyethyl) isocyanurate, 0.8 part of tricyclo[5.2.1.02,6]dec-8-yl methacrylate, 0.3 part of 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 1 part of 2-vinylpyridine, and 30 parts of diluent.

[0029] The heat-conducting filler is spherical alumina; the average particle size of the spherical alumina is 10 μm; the flame retardant is aluminum hydroxide flame retardant H-WF-10; the dispersant is silane coupling agent KH550; the black filler is carbon black; the particle size of the black filler is 1000 mesh.

[0030] The acrylate-capped hyperbranched silicone-modified polyurethane is prepared by the method of Example 1 in the authorized announcement number CN111393608B; the curing agent is a mixture of benzoin ethyl ether, azobisisobutyronitrile, and benzoin isopropyl ether in a mass ratio of 1:0.8:1; the diluent is a mixture formed by mixing butyl acrylate, dipropylene glycol diacrylate, and 2-methoxyethyl acrylate in a mass ratio of 1:1:1.

[0031] The first grid release layer and the second grid release layer are each independently made of a PET release film with a grid pattern; the grid walls of the PET release film with a grid pattern are convex in shape, and its cross-section is trapezoidal; the width of the grid wall is 4 μm, the depth of the grid wall is 1 μm, and the distance between the grid walls is 130 μm; the included angle between the transverse and longitudinal grid wall intersection positions of the PET release film with a grid pattern is 90°; the thickness of the heat-conducting adhesive layer is 80 μm.

[0032] A preparation method of the black substrate-free grid exhaust heat-conducting double-sided tape comprises the following steps:

[0033] Step S1, mixing and stirring the raw materials of the heat-conducting adhesive layer according to the weight parts, ultrasonically dispersing, and evacuating to remove bubbles to obtain a heat-conducting adhesive;

[0034] Step S2: Uniformly coat the thermal conductive adhesive prepared in Step S1 on the first grid release layer, cover the second grid release layer on the thermal conductive adhesive layer, irradiate it under ultraviolet light, and then bake it at 50 °C for 3 minutes. After curing, a black substrate-free grid exhaust heat-conducting double-sided tape is obtained; the wavelength of the ultraviolet light is 365 nm, and the irradiation time is 4 min.

[0035] Example 2

[0036] A black substrate-free grid exhaust heat-conducting double-sided tape includes a first grid release layer, a thermal conductive adhesive layer, and a second grid release layer that are sequentially laminated; the thermal conductive adhesive layer is made of the following raw materials by weight: 30 parts of a heat-conducting filler, 5 parts of a flame retardant, 0.3 part of a dispersant, 2 parts of a black filler, 25 parts of an acrylate-capped hyperbranched organosilicon-modified polyurethane, 0.3 part of a curing agent, 1.5 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt, 1.5 parts of 4-acryloylhydroxybenzoic acid phenyl ketone, 2.5 parts of 2,4,6-trivinylcyclotriboroxane, 0.8 part of tris(2-acryloyloxyethyl) isocyanurate, 0.9 part of tricyclo[5.2.1.02,6]dec-8-yl methacrylate, 0.4 part of 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 1.5 parts of 2-vinylpyridine, and 32 parts of a diluent.

[0037] The heat-conducting filler is hexagonal boron nitride; the hexagonal boron nitride is 1.5 μm; the flame retardant is magnesium hydroxide flame retardant XS-MHB-3; the dispersant is silane coupling agent KH560; the black filler is graphite; the particle size of the black filler is 1100 mesh.

[0038] The acrylate-capped hyperbranched organosilicon-modified polyurethane is prepared by the method in Example 1 of the authorized announcement number CN111393608B; the curing agent is a mixture of benzoin ethyl ether, azobisisobutyronitrile, and benzoin isopropyl ether in a mass ratio of 1.5:0.9:1; the diluent is a mixture formed by mixing butyl acrylate, dipropylene glycol diacrylate, and 2-methoxyethyl acrylate in a mass ratio of 1.2:1:1.5.

[0039] The first grid release layer and the second grid release layer are independently made of a PET release film with a grid pattern; the grid wall of the PET release film with a grid pattern is in a convex shape, and its cross-section is triangular; the width of the grid wall is 10 μm, the depth of the grid wall is 1.5 μm, and the distance between the grid walls is 150 μm; the included angle between the transverse and longitudinal grid wall intersection positions of the PET release film with a grid pattern is 110°; the thickness of the thermal conductive adhesive layer is 80 μm.

[0040] A preparation method of the black substrate-free grid exhaust heat-conducting double-sided tape, comprising the following steps:

[0041] Step S1: Mix and stir the raw materials of the heat-conducting adhesive layer according to parts by weight, disperse ultrasonically, and evacuate to remove bubbles to obtain a heat-conducting adhesive;

[0042] Step S2: Uniformly coat the heat-conducting adhesive prepared in Step S1 on the first grid release layer, cover the second grid release layer on the heat-conducting adhesive layer, irradiate under ultraviolet light, and then bake at 55 °C for 4 minutes to obtain a black substrate-free grid exhaust heat-conducting double-sided tape after curing; the wavelength of the ultraviolet light is 365 nm, and the irradiation time is 4 min.

[0043] Example 3

[0044] A black substrate-free grid exhaust heat-conducting double-sided tape, comprising a first grid release layer, a heat-conducting adhesive layer and a second grid release layer which are sequentially stacked; the heat-conducting adhesive layer is made of the following raw materials according to parts by weight: 35 parts of a heat-conducting filler, 6 parts of a flame retardant, 0.6 part of a dispersant, 3.5 parts of a black filler, 30 parts of an acrylate-capped hyperbranched organosilicon-modified polyurethane, 0.6 part of a curing agent, 2 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt, 2 parts of 4-acryloylhydroxybenzoic acid benzophenone, 3 parts of 2,4,6-trivinylcyclotriboroxane, 1 part of tris(2-acryloyloxyethyl) isocyanurate, 1 part of tricyclo[5.2.1.02,6]dec-8-yl methacrylate, 0.45 part of 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 2 parts of 2-vinylpyridine, and 35 parts of a diluent.

[0045] The heat-conducting filler is aluminum nitride whiskers; the diameter of the aluminum nitride whiskers is 10 μm and the length is 1 cm; the flame retardant is aluminum hydroxide flame retardant H-WF-10; the dispersant is silane coupling agent KH570; the black filler is carbon nanotubes; the particle size of the black filler is 1300 mesh.

[0046] The acrylate-capped hyperbranched organosilicon-modified polyurethane is prepared by the method of Example 1 in the authorized announcement number CN111393608B; the curing agent is a mixture of benzoin ethyl ether, azobisisobutyronitrile and benzoin isopropyl ether in a mass ratio of 2:1:1; the diluent is a mixture formed by mixing butyl acrylate, dipropylene glycol diacrylate and 2-methoxyethyl acrylate in a mass ratio of 1.5:1:2.

[0047] The first grid release layer and the second grid release layer are independently made of PET release films with grid patterns respectively; the grid walls of the PET release films with grid patterns are in a convex shape, and their cross-sections are inverted U-shaped; the width of the grid walls is 12 μm, the depth of the grid walls is 2 μm, and the distance between the grid walls is 170 μm; the included angle between the transverse and longitudinal grid wall intersection positions of the PET release films with grid patterns is 130°; the thickness of the thermal conductive adhesive layer is 80 μm.

[0048] A preparation method of the black substrate-free grid exhaust heat-conducting double-sided tape includes the following steps:

[0049] Step S1: Mix and stir the raw materials of the thermal conductive adhesive layer by weight, disperse them ultrasonically, and evacuate to remove bubbles to obtain the thermal conductive adhesive;

[0050] Step S2: Uniformly coat the thermal conductive adhesive prepared in Step S1 on the first grid release layer, cover the second grid release layer on the thermal conductive adhesive layer, irradiate it under ultraviolet light, and then bake it at 60 °C for 4.5 minutes to obtain the black substrate-free grid exhaust heat-conducting double-sided tape after curing; the wavelength of the ultraviolet light is 365 nm, and the irradiation time is 4 min.

[0051] Example 4

[0052] A black substrate-free grid exhaust heat-conducting double-sided tape includes a first grid release layer, a thermal conductive adhesive layer, and a second grid release layer that are sequentially laminated; the thermal conductive adhesive layer is made of the following raw materials by weight: 45 parts of a thermal conductive filler, 9 parts of a flame retardant, 0.8 part of a dispersant, 4 parts of a black filler, 35 parts of an acrylate-capped hyperbranched organosilicon-modified polyurethane, 0.8 part of a curing agent, 2.5 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt, 2.5 parts of 4-acryloylhydroxybenzoic acid phenyl ketone, 3.5 parts of 2,4,6-trivinylcyclotriboroxane, 1.3 parts of tris(2-acryloyloxyethyl) isocyanurate, 1.1 parts of tricyclo[5.2.1.02,6]dec-8-yl methacrylate, 0.55 part of 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 2.5 parts of 2-vinylpyridine, and 38 parts of a diluent.

[0053] The thermal conductive filler is a mixture formed by mixing spherical alumina, hexagonal boron nitride, and aluminum nitride whiskers in a mass ratio of 1:2:1; the average particle size of the spherical alumina is 20 μm; the hexagonal boron nitride is 2 μm; the diameter of the aluminum nitride whiskers is 5 μm and the length is 0.5 cm; the flame retardant is a mixture formed by mixing aluminum hydroxide flame retardant H-WF-10 and magnesium hydroxide flame retardant XS-MHB-3 in a mass ratio of 3:5; the dispersant is a mixture formed by mixing silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570 in a mass ratio of 1:3:5; the black filler is a mixture formed by mixing carbon black, graphite, carbon nanotubes, and graphene in a mass ratio of 1:1:3:2; the particle size of the black filler is 1400 mesh.

[0054] The acrylate-capped hyperbranched organosilicon-modified polyurethane is prepared by the method of Example 1 in the authorized announcement number CN111393608B; the curing agent is a mixture formed by mixing benzoin ethyl ether, azobisisobutyronitrile, and benzoin isopropyl ether in a mass ratio of 2.5:1.1:1; the diluent is a mixture formed by mixing butyl acrylate, dipropylene glycol diacrylate, and 2-methoxyethyl acrylate in a mass ratio of 1.8:1:2.5.

[0055] The first grid release layer and the second grid release layer are independently made of a PET release film with a grid pattern; the grid walls of the PET release film with a grid pattern are in a convex shape, and its cross-section is rectangular; the width of the grid walls is 18 μm, the depth of the grid walls is 2.5 μm, and the distance between the grid walls is 200 μm; the included angle between the transverse and longitudinal grid wall intersection positions of the PET release film with a grid pattern is 160°; the thickness of the thermal conductive adhesive layer is 80 μm.

[0056] A preparation method of the black substrate-free grid exhaust thermal conductive double-sided tape includes the following steps:

[0057] Step S1: Mix and stir the raw materials of the thermal conductive adhesive layer by weight, disperse them ultrasonically, and evacuate to remove bubbles to obtain the thermal conductive adhesive.

[0058] Step S2: Uniformly coat the thermal conductive adhesive prepared in Step S1 on the first grid release layer, cover the second grid release layer on the thermal conductive adhesive layer, irradiate it under ultraviolet light, and then bake it at 65°C for 5 minutes to obtain the black substrate-free grid exhaust thermal conductive double-sided tape after curing; the wavelength of the ultraviolet light is 365 nm and the irradiation time is 4 min.

[0059] Example 5

[0060] A black substrate-free grid exhaust heat-conducting double-sided tape, comprising a first grid release layer, a heat-conducting adhesive layer, and a second grid release layer which are sequentially stacked; the heat-conducting adhesive layer is made of the following raw materials by weight: 50 parts of heat-conducting filler, 10 parts of flame retardant, 1 part of dispersant, 5 parts of black filler, 40 parts of acrylate-capped hyperbranched organosilicon-modified polyurethane, 1 part of curing agent, 3 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt, 3 parts of 4-acryloylhydroxybenzoic acid benzophenone, 4 parts of 2,4,6-trivinylcyclotriboroxane, 1.5 parts of tris(2-acryloyloxyethyl) isocyanurate, 1.2 parts of tricyclo[5.2.1.02,6]dec-8-yl methacrylate, 0.6 part of 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 3 parts of 2-vinylpyridine, and 40 parts of diluent.

[0061] The heat-conducting filler is spherical alumina; the average particle size of the spherical alumina is 30 μm; the flame retardant is aluminum hydroxide flame retardant H-WF-10; the dispersant is silane coupling agent KH560; the black filler is graphite; the particle size of the black filler is 1500 mesh; the acrylate-capped hyperbranched organosilicon-modified polyurethane is prepared by the method of Example 1 in the authorized announcement number CN111393608B; the curing agent is a mixture of benzoin ethyl ether, azobisisobutyronitrile, and benzoin isopropyl ether in a mass ratio of 3:1.2:1; the diluent is a mixture formed by mixing butyl acrylate, dipropylene glycol diacrylate, and 2-methoxyethyl acrylate in a mass ratio of 2:1:3.

[0062] The first grid release layer and the second grid release layer are independently made of PET release films with grid patterns; the grid walls of the PET release films with grid patterns are in a convex shape, and the cross section is hemispherical; the width of the grid walls is 20 μm, the depth of the grid walls is 3 μm, and the distance between the grid walls is 210 μm; the included angle between the transverse and longitudinal grid wall intersection positions of the PET release films with grid patterns is 180°; the thickness of the heat-conducting adhesive layer is 80 μm.

[0063] A preparation method of the black substrate-free grid exhaust heat-conducting double-sided tape comprises the following steps:

[0064] Step S1, mixing and stirring the raw materials of the heat-conducting adhesive layer according to the weight parts, ultrasonically dispersing, and vacuumizing to remove bubbles to obtain a heat-conducting adhesive;

[0065] Step S2: Uniformly coat the thermal conductive adhesive prepared in Step S1 on the first grid release layer, cover the second grid release layer on the thermal conductive adhesive layer, irradiate it under ultraviolet light, and then bake it at 70 °C for 6 minutes. After curing, a black substrate-free grid exhaust heat-conducting double-sided tape is obtained; the wavelength of the ultraviolet light is 365 nm, and the irradiation time is 4 min.

[0066] Comparative Example 1

[0067] A black substrate-free grid exhaust heat-conducting double-sided tape and its preparation method are basically the same as those in Example 1, except that 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt and 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline are not added.

[0068] Comparative Example 2

[0069] A black substrate-free grid exhaust heat-conducting double-sided tape and its preparation method are basically the same as those in Example 1, except that 2-vinylpyridine and 4-acryloylhydroxybenzoic acid benzophenone are not added.

[0070] To further illustrate the beneficial technical effects of the black substrate-free grid exhaust heat-conducting double-sided tape involved in each embodiment of the present invention, relevant performance tests are carried out on the black substrate-free grid exhaust heat-conducting double-sided tapes involved in Examples 1-5 and Comparative Examples 1-2; the test methods are as follows:

[0071] (1) Thermal conductivity: The thermal conductivity is tested with reference to ASTM-D5470.

[0072] (2) Peel strength: The 180-degree peel strength test on the SUS steel plate is carried out according to GB / T2792-2014.

[0073] (3) Damp heat aging resistance: Place the black substrate-free grid exhaust heat-conducting double-sided tape of each example in an environment of 90 °C and relative humidity of 95% for 150 hours. After cooling to room temperature, re-detect the 180-degree peel strength according to the method in (2), and calculate the retention rate of the 180-degree peel strength. The larger the value, the better the damp heat aging resistance.

[0074] (4) High temperature resistance: Place the test samples of each example in an aging oven at 95 °C for 1000 hours. After cooling to room temperature, test the 180-degree peel strength according to the method in (2) again, and calculate the retention rate of the 180-degree peel strength. The larger the value, the better the high temperature resistance.

[0075] (5) Bonding usability: Visually check for bubbles.

[0076] The UV curing equipment on which the above tests are based is: an LED UV curing lamp, model: XC210-YJ, light source wavelength: 365 nm, UV intensity: 1000 mW / CM 2 , irradiation time: 4 min.

[0077] Table 1

[0078] Test Items Thermal Conductivity Peel Strength at 180 Degrees Moisture and Heat Aging Resistance High Temperature Resistance Fitting Usability Unit W / (m·K) N / cm ％ ％ — Example 1 0.99 12.0 99.23 99.41 No Bubbles Example 2 1.18 12.3 99.35 99.50 No Bubbles Example 3 1.06 12.5 99.55 99.63 No Bubbles Example 4 1.35 12.6 99.70 99.83 No Bubbles Example 5 1.30 13.1 99.81 99.95 No Bubbles Comparative Example 1 0.83 9.5 95.49 96.62 No Bubbles Comparative Example 2 0.92 10.8 97.76 98.05 No Bubbles

[0079] As can be seen from Table 1, compared with the products of the comparative examples, the black substrate-free grid exhaust heat-conducting double-sided tape made in each embodiment of the present invention has better heat-conducting performance, bonding performance, resistance to damp heat aging performance and high-temperature resistance, and has good fitting usability. The combined use of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate, 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 2-vinylpyridine and 4-acryloylhydroxybenzophenone is beneficial to improving the above performances.

[0080] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. It should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A black substrate-free mesh exhaust thermal conductive double-sided tape, characterized in that: The invention comprises a first grid release layer, a heat conductive adhesive layer and a second grid release layer which are sequentially stacked; the heat conductive adhesive layer is made of the following raw materials in parts by weight: 20-50 parts of heat conductive filler, 0-10 parts of flame retardant, 0.1-1 parts of dispersant, 0.1-5 parts of black filler, 20-40 parts of acrylate-terminated hyperbranched silicone-modified polyurethane, 0.1-1 parts of curing agent, 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane -1-sulfonic acid inner salt 1-3 parts, 4-acryloylhydroxybenzoic acid benzophenone 1-3 parts, 2,4,6-trivinyl cycloboroxine 2-4 parts, tris (2-acryloyloxyethyl) isocyanurate 0.5-1.5 parts, methacrylate tricyclo [5.2.1.02,6] dec-8-yl ester 0.8-1.2 parts, 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline 0.3-0.6 parts, 2-vinyl pyridine 1-3 parts, diluent 30-40 parts; The acrylate-terminated hyperbranched organosilicon-modified polyurethane is prepared by the following method: under nitrogen protection, 100 g of polytetramethylene ether glycol with an average molecular weight of 2000, 30 g of HO(Me2SiO) 100 H and 1.34 g of trimethylolpropane were added into a 250 mL three-necked flask equipped with a mechanical stirrer and a thermometer. After stirring evenly, the temperature was reduced to 110°C / 130 mmHg to remove moisture for 2 hours, then the temperature was lowered to 40°C, 0.10 g of dibutyltin dilaurate was added dropwise, 21.65 g of IPDI was added dropwise, and after reacting at 40°C for 6 hours, 8.45 g of hydroxypropyl methacrylate was added, and the reaction was continued at 40°C for 8 hours to obtain an acrylate-terminated hyperbranched silicone-modified polyurethane.

2. The black substrate-free mesh exhaust thermally conductive double-sided tape according to claim 1, characterized in that: The thermal conductive filler is any one or more of spherical aluminum oxide, hexagonal boron nitride, and aluminum nitride whiskers.

3. The black substrate-free mesh exhaust thermally conductive double-sided tape according to claim 2, characterized in that: The average particle size of the spherical aluminum oxide is 10-30 μm; the average particle size of the hexagonal boron nitride is 1-3 μm; the average particle size of the aluminum nitride whisker is 2-30 μm in diameter and 0.5-3 cm in length.

4. The black substrate-free mesh exhaust thermally conductive double-sided tape according to claim 1, characterized in that: The flame retardant is at least one of aluminum hydroxide flame retardant H-WF-10 and magnesium hydroxide flame retardant XS-MHB-3; the dispersant is at least one of silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570.

5. The black substrate-free mesh exhaust thermally conductive double-sided tape according to claim 1, characterized in that: The black filler is at least one of carbon black, graphite, carbon nanotubes and graphene; and the particle size of the black filler is 1000-1500 meshes.

6. The black substrate-free mesh exhaust thermally conductive double-sided tape according to claim 1, characterized in that: The curing agent is prepared by mixing benzoin ethyl ether, azobisisobutyronitrile and benzoin isopropyl ether in a mass ratio of (1-3):(0.8-1.2):

1.

7. The black substrate-free mesh exhaust thermally conductive double-sided tape according to claim 1, characterized in that: The diluent is a mixture of butyl acrylate, tripropylene glycol diacrylate and 2-methoxyethyl acrylate in a mass ratio of (1-2):1:(1-3).

8. The black substrate-free mesh exhaust thermally conductive double-sided tape according to claim 1, characterized in that: The first grid release layer and the second grid release layer are independently made of PET release films with grid patterns; the mesh wall of the PET release film with a grid pattern is a convex shape, and its cross-section is one of a trapezoid, a triangle, an inverted U-shape, a rectangle, and a hemispherical shape; the mesh wall width is 4-20 μm, the mesh wall depth is 1-3 μm, and the distance between the mesh walls is 130-210 μm; the angle between the transverse and longitudinal mesh walls of the PET release film with a grid pattern is 90-180°.

9. The black substrate-free mesh exhaust thermally conductive double-sided tape according to claim 1, characterized in that: The thickness of the thermal conductive adhesive layer is 10-150 μm.

10. A method for preparing the black substrate-free mesh exhaust thermally conductive double-sided adhesive tape according to any one of claims 1 to 9, characterized in that: The steps include: Step S1, mixing and stirring the raw materials of the thermal conductive adhesive layer according to parts by weight, ultrasonically dispersing, and vacuuming to remove bubbles to obtain a thermal conductive adhesive; Step S2, uniformly coating the thermally conductive adhesive prepared in step S1 on the first grid release layer, and covering the thermally conductive adhesive layer with a second grid release layer, irradiating the layer under ultraviolet light, and then baking the layer at 50-70°C for 3-6 minutes to obtain a black substrate-free grid exhaust thermally conductive double-sided tape after curing; the wavelength of the ultraviolet light is 300-400nm, and the irradiation time is 3-5min.