CN112480447A - High-out-of-plane thermal conductivity coefficient polyimide film and preparation method thereof - Google Patents

High-out-of-plane thermal conductivity coefficient polyimide film and preparation method thereof Download PDF

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CN112480447A
CN112480447A CN202011355242.4A CN202011355242A CN112480447A CN 112480447 A CN112480447 A CN 112480447A CN 202011355242 A CN202011355242 A CN 202011355242A CN 112480447 A CN112480447 A CN 112480447A
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acid resin
film
thermal conductivity
polyamic acid
heat
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CN112480447B (en
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蒋耿杰
青双桂
姬亚宁
周福龙
马纪翔
潘钦鹏
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Guilin Electrical Equipment Scientific Research Institute Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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    • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
    • C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/28—Nitrogen-containing compounds
    • C08K2003/282—Binary compounds of nitrogen with aluminium
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/38—Boron-containing compounds
    • C08K2003/382—Boron-containing compounds and nitrogen
    • C08K2003/385—Binary compounds of nitrogen with boron
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00—Use of pretreated ingredients
    • C08K9/04—Ingredients treated with organic substances
    • C08K9/06—Ingredients treated with organic substances with silicon-containing compounds

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Abstract

The invention discloses a polyimide film with a high out-of-plane thermal conductivity coefficient and a preparation method thereof, belonging to the technical field of polyimide materials. Compared with the prior art, the preparation method of the polyimide film with the high out-of-plane thermal conductivity coefficient is different from the prior art in that: applying the action of an electric field in the process that the defoamed polyamic acid resin is extruded from a die lip of a die head of a film casting extrusion device to fall to a support, wherein the direction of the electric field is vertical to the falling direction of the defoamed polyamic acid resin; when the hot air passes through the casting furnace, hot air which faces upwards and is over against the back surface of the support body is applied between the front roller and the rear roller, and the temperature of the hot air is 150-170 ℃. The polyimide film prepared by the method has high out-of-plane thermal conductivity and in-plane thermal conductivity, and also has good electrical property and mechanical property, and the self-supporting film prepared by the method can be easily and completely peeled from a support body on the premise of not adding a release agent.

Description

High-out-of-plane thermal conductivity coefficient polyimide film and preparation method thereof
Technical Field
The invention relates to a polyimide material, in particular to a polyimide film with high out-of-plane thermal conductivity coefficient and a preparation method thereof.
Background
Polyimide (PI) film is a film-like insulating material with the best comprehensive performance, and is widely applied to the fields of microelectronics, electronic packaging and the like. In recent years, electronic components are developed towards high density, high power, high integration and light weight, a large amount of heat is inevitably generated in the operation and working processes, and if the heat dissipation problem cannot be timely and effectively solved, the working efficiency, reliability and service life of the electronic components are directly influenced. In order to ensure that the electronic components can work normally with high reliability for a long time, the thermal conductivity of the polyimide film must be improved on the basis of ensuring the insulation.
It is a common method to improve the thermal conductivity of polyimide film by uniformly doping polyamide acid resin with thermal conductive filler including alumina, silica, silicon nitride, boron nitride, etc. Theoretically, though the film can be endowed with a high heat conductivity coefficient by doping a large amount of heat-conducting fillers, the mechanical property and the insulating property of the film are greatly reduced because the fillers in the film are easy to agglomerate. Further, the large amount of the heat conductive filler added also causes difficulty in peeling the self-supporting film from the support.
The invention patent with publication number CN108610631A adopts two polyamide acid resins with a difference value of dissolution interaction parameters of 2.5-5.0 to compound, and the heat-conducting filler only exists in one resin to form a heat-conducting channel which is continuous and vertical to the surface of the film, thereby obtaining the polyimide film which has both heat-conducting property and mechanical property while the filler doping amount is low, when the dosage of the heat-conducting filler is 25%, the out-of-plane heat-conducting coefficient of the film is 1.5W/m.K, the tensile strength is 80MPa, and the elongation at break is 5.64%. However, as is well known in the art, the composite film with the added heat-conducting filler has the characteristic of isotropy, and the heat transfer has two ways of heat diffusion along the film surface and out of the film surface, and mainly takes heat diffusion along the film surface. Said invention constructs a heat-conducting channel perpendicular to film surface, i.e. the heat quantity only can be diffused outwards but not in the film surface, in the practical application, the heat quantity can be directly passed through the contact portion of film and heat source and perpendicularly fed into radiator, and has no in-plane diffusion process, and its heat-transferring area is small and heat-transferring effect is poor.
The effect of improving the thermal conductivity coefficient of the film and simultaneously considering the mechanical property of the film can be obtained by uniformly doping the resin with the thermal conductive filler with different particle sizes and different components. For example, in patent publication No. CN 110540752a, polyamide acid resin is doped with at least two kinds of heat conductive fillers with different morphologies, which are sheet-like heat conductive fillers, and defoamed polyamide acid resin is extruded and filmed through a long and narrow extruder die channel with gradually changing cross-sectional area, and then is subjected to thermal imidization to obtain a highly heat conductive polyimide film. When the flaky filler passes through a die head channel, the flaky filler is subjected to shearing action and oriented in the plane of the film, so that high in-plane thermal conductivity is obtained; the non-sheet filler forms heat-conducting connection between the sheet fillers, and the heat-conducting connection is further enhanced through calendering, so that high out-of-plane heat conductivity is obtained. The film obtained has an in-plane thermal conductivity of 2.85 to 4.05W/mK and an out-of-plane thermal conductivity of 0.64 to 0.97W/mK. However, the thickness of the mainstream heat conducting film product in the current market is 25 μm and 38 μm, that is, the maximum particle size of the filler must be less than 25 μm, the position with the smallest channel size of the conventional die head is the lip of the die lip, the opening degree of the lip is 0.2-0.6 mm, and is far greater than the particle size of the filler, so that the sheet filler in the invention is difficult to achieve the orientation effect described in the patent when the conventional die head is used for extrusion.
Disclosure of Invention
The invention aims to provide a polyimide film with high out-of-plane thermal conductivity coefficient, which has both thermal conductivity and electrical performance and is easy to peel, and a preparation method thereof.
In order to solve the technical problems, the invention adopts the following technical scheme:
a preparation method of a polyimide film with high out-of-plane thermal conductivity coefficient comprises the following steps:
1) obtaining polyamic acid resin doped with heat-conducting filler modified by silane coupling agent containing amino functional group, and defoaming to obtain defoaming polyamic acid resin;
2) casting the obtained defoaming polyamic acid resin on a support body by a film casting extrusion device, and removing partial solvent by a casting furnace to obtain a self-supporting film; wherein, the support body is supported by a front roller and a rear roller and is driven to pass through the casting furnace;
3) imidizing the self-supporting film to obtain the polyimide film with the high out-of-plane thermal conductivity coefficient;
in contrast to the prior art, the present invention,
in the step 2), the defoaming polyamic acid resin is acted by an electric field in the process of extruding from a die lip of a die head of film casting extrusion equipment to fall to a support body, and the direction of the electric field is vertical to the falling direction of the defoaming polyamic acid resin; and applying hot air which faces upwards and is over against the back surface of the support body between the front roller and the rear roller, wherein the temperature of the hot air is 150-170 ℃.
In step 1) of the above preparation method, the amino-functional silane coupling agent may be specifically one or a combination of two or more selected from the group consisting of KH-550(γ -aminopropyltriethoxysilane), KH-540(γ -aminopropyltrimethoxysilane), KH-792(N- β - (aminoethyl) - γ -aminopropyltrimethoxysilane), KH-602(N- (β -aminoethyl) -3-aminopropylmethyldimethoxysilane), HD-M8372, HD-E8133, HD-M8253, HD-M8252 and HD-M8132. The heat-conducting filler is preferably one or a combination of more than two of boron nitride, aluminum nitride and silicon carbide, the particle size of the heat-conducting filler is preferably micron-sized, and the doping amount is preferably 25-40 wt% of the total weight of the heat-conducting filler, diamine and dianhydride for forming the polyamide acid resin.
The solid content of the polyamic acid resin doped with the thermal conductive filler modified by the amino group-containing silane coupling agent in step 1) of the preparation method is usually 10 to 25 wt%, preferably 15 to 20 wt%, and the viscosity thereof is preferably controlled to 20000 to 50000 cp. The resin with lower viscosity has better fluidity, can avoid the conditions of filter element blockage and unstable discharge, more importantly, reduces the moving resistance of the heat-conducting filler particles, and further improves the moving or turning speed of the heat-conducting filler particles in an electric field.
The polyamic acid resin is prepared by a conventional in-situ polymerization method, such as a known method that diamine and dianhydride are placed in an aprotic polar solvent to carry out polycondensation reaction. Wherein, the selection and the dosage of the diamine, the dianhydride and the aprotic polar solvent are the same as those of the prior art, and the temperature and the time of the polycondensation reaction are also the same as those of the prior art. Specifically, the method comprises the following steps:
the diamine may be one or a combination of two or more selected from 4,4 '-diaminodiphenyl ether (ODA), 3, 4' -diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, and biphenyldiamine.
The dianhydride may be one or a combination of any two or more selected from pyromellitic dianhydride (PMDA), 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3 ', 4' -biphenyltetracarboxylic dianhydride (a-BPDA), 3,3 ', 4, 4' -diphenylethertetracarboxylic dianhydride (ODPA), 2,3,3 ', 4' -diphenylethertetracarboxylic dianhydride, and 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride (BTDA).
The diamine to dianhydride mole ratio is typically 1: 0.95 to 1.05, more preferably 1: 0.99 to 1.01.
The aprotic polar solvent may be one or a combination of two or more selected from N, N-Dimethylacetamide (DMAC), N-Dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), N-diethylacetamide, and N, N-diethylformamide.
In the step 1) of the preparation method, the heat-conducting filler is modified by using a silane coupling agent containing an amino functional group in an aprotic polar solvent, and the obtained mixed solution is mixed and doped into a polymerization process of diamine and dianhydride. The modification is usually carried out under ultrasonic conditions, and the ultrasonic time is usually more than or equal to 1 h. The aprotic polar solvent for dispersing the heat conductive filler is selected as described above, and the dosage of the aprotic polar solvent is matched with the dosage of the aprotic polar solvent in the subsequent diamine and dianhydride polymerization so that the solid content of the obtained polyamic acid resin can meet the requirement.
In the step 2) of the preparation method, the application of the electric field enables the heat-conducting filler particles to move along the direction of the electric field (move from bottom to top in the thickness direction of the liquid film) and turn, and the filler particles are oriented towards the same direction, so that the filler particles are easier to lap to form a heat-conducting channel, the heat conductivity in the orientation direction is improved, namely the heat conductivity of the film in the vertical direction, and the high out-of-plane heat conductivity is obtained. Preferably, the electric field intensity is 1-10 kV/mm. The distance between the lip of the die lip and the support body is more than or equal to 5cm, and preferably 5-15 cm. When the electric field intensity is 1-10 kV/mm, and the distance between the lip of the die lip and the support body is 5-15 cm, the running speed of the support body is preferably 4-10 m/min, and is further preferably 7-10 m/min.
In step 2) of the preparation method, the setting of the temperature of the upper drying tunnel and the temperature of the lower drying tunnel during casting film forming is the same as that of the prior art, specifically, the temperature of the upper drying tunnel is set to be 90-170 ℃, and the temperature of the lower drying tunnel is set to be 140-190 ℃.
In the step 2) of the above preparation method, by applying hot air to a specific region on the back surface of the support (in the conventional casting process, only the air surface of the liquid film on the support (i.e., the surface of the liquid film in contact with the air) is blown and heated, the curing speed of the air surface of the liquid film is high, and the solvent in the resin on the surface of the liquid film support (i.e., the surface of the liquid film in contact with the support) is difficult to be discharged from the air surface), on the one hand, the evaporation of the solvent in the resin on the surface of the liquid film support is accelerated, and the solvent in the resin on the support surface is discharged before the air surface of the liquid; on the other hand, the heat-conducting filler particles after moving under the action of the electric field are quickly fixed, and the orientation of the heat-conducting filler particles is maintained, so that the polyimide film obtained obtains high heat conductivity and has both mechanical property and electrical property. In addition, the applicant has found, unexpectedly, that the application of hot air to specific areas of the back of the support also allows the resulting self-supporting film to be easily and completely peeled from the support without the addition of a release agent.
In step 2) of the above production method, the self-supporting film is obtained and then imidized without being drawn longitudinally or transversely. The thermal imidization treatment is the same as the prior art, and generally comprises three stages of preheating, imidization and setting, wherein the temperature of the preheating stage is generally 120-230 ℃, the temperature of the imidization stage is generally 300-400 ℃, and the temperature of the setting stage is generally 410-450 ℃.
The invention also comprises the polyimide film with high out-of-plane thermal conductivity coefficient prepared by the method, wherein the in-plane thermal conductivity coefficient of the film is more than 3.30W/m.K, the out-of-plane thermal conductivity coefficient is more than 0.9W/m.K, the tensile strength is more than 80MPa, and the elongation at break is more than or equal to 30%.
Compared with the prior art, the invention is characterized in that:
1. the silane coupling agent with amino functional groups is adopted to carry out surface modification on the heat-conducting filler, so that the surface of the heat-conducting filler is positively charged, the dispersibility of the heat-conducting filler is improved, and meanwhile, the interface bonding force between the heat-conducting filler and a resin matrix is improved.
2. The modified heat-conducting filler particles are positively charged, an electric field perpendicular to the falling direction of the defoamed polyamic acid resin is applied to the defoamed polyamic acid resin extruded from a die lip to the process of falling to a support body in a casting film forming process (namely, the direction of the electric field is parallel to the thickness direction of a liquid film formed in the falling process), so that the heat-conducting filler particles move along the direction of the electric field (move from bottom to top in the thickness direction of the liquid film) and turn, and the filler particles are oriented towards the same direction, so that a heat-conducting channel is formed by more easily lapping, and the heat conductivity in the orientation direction is improved, namely the heat conductivity in the vertical direction of the; and further, hot air is applied to a specific area on the back surface of the support body to quickly fix the heat-conducting filler particles after the particles are moved under the action of an electric field, and the orientation of the heat-conducting particles is maintained, so that the obtained self-supporting film is easier to peel off from the support body on the premise of not adding a release agent, and the obtained polyimide film has high out-of-plane heat conductivity and in-plane heat conductivity and also has good electrical performance and mechanical performance.
Detailed Description
The present invention will be better understood from the following detailed description of specific examples, which should not be construed as limiting the scope of the present invention.
Example 1
1) Mixing 43.33kg of heat-conducting filler (boron nitride (the particle size is 0.1-20 mu M), 390kg of N, N-dimethylacetamide and 0.65kg of amino-functional group-containing silane coupling agent (HD-M8372), and carrying out ultrasonic treatment for 2 hours to obtain a mixed solution for later use;
2) at normal temperature, adding 31.11kg of 4, 4' -diaminodiphenyl ether (ODA) and 45kg of Dimethylacetamide (DMAC) into a reaction kettle according to a conventional process, stirring and dissolving, adding the mixed solution obtained in the step 1), uniformly stirring, and then mixing with diamine according to a molar ratio of 1: 1 (PMDA) is added in batches to synthesize polyamide acid resin with the viscosity of 3.5 ten thousand centipoise (the doping amount of the heat-conducting filler is 40wt percent), and defoaming is carried out to obtain defoaming polyamide acid resin;
3) adjusting a die head of the film casting extrusion equipment to enable the vertical distance between the lip of the upper die lip of the die head and the steel belt to be 10 cm;
4) setting the running speed of a steel belt to be 7m/min, wherein the steel belt is supported by a front roller and a rear roller and is driven to pass through a casting furnace, the temperature of an upper drying tunnel in the casting furnace is 150 ℃, and the temperature of a lower drying tunnel in the casting furnace is 170 ℃; applying hot air which faces upwards and is over against the back surface of the support body between the front roller and the rear roller, wherein the temperature of the hot air is 160 ℃; after the temperature is stabilized, arranging an alternating current electric field with the strength of 10kV/mm between the lip of the die lip and the steel belt, wherein the direction of the electric field is vertical to the falling direction of the defoaming polyamide acid resin;
5) extruding and casting the obtained defoaming polyamic acid resin onto a steel belt through a die lip on a die head of film casting extrusion equipment to form a film, and removing partial solvent through a casting furnace to obtain a self-supporting film;
6) the obtained support film enters an imidization furnace at the speed of 7m/min, and sequentially passes through a preheating temperature section of 150-200 ℃, an imidization temperature section of 320-390 ℃ and a setting temperature section of 410-440 ℃ to obtain the high-out-of-plane thermal conductivity coefficient polyimide film.
Example 2
Example 1 was repeated, with the difference from example 1 that:
the silane coupling agent containing amino functional groups is KH-540, the heat-conducting filler is aluminum nitride, the doping amount is 32 wt%, the alternating-current electric field intensity is 7.5kV/mm, the viscosity of the synthesized polyamide acid resin is 5.0 ten thousand centipoise, and the vertical distance between the lip of the die lip and the steel strip is 5 cm.
Example 3
Example 1 was repeated, with the difference from example 1 that:
the silane coupling agent containing amino functional groups is KH-550, the doping amount of the heat-conducting filler is 25 wt%, the alternating-current electric field intensity is 5kV/mm, the viscosity of the synthesized polyamide acid resin is 2.0 ten thousand centipoise, and the vertical distance between the lip of the die lip and the steel strip is 15 cm.
Example 4
Example 1 was repeated, with the difference from example 1 that:
the silane coupling agent containing amino functional groups is KH-792, the diamine is p-phenylenediamine, the dianhydride is 3,3 ', 4, 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), the doping amount of the heat-conducting filler is 25 wt%, the alternating-current electric field intensity is 2.5kV/mm, the viscosity of the synthesized polyamide acid resin is 2.0 ten thousand centipoises, the running speed of a steel belt is 4m/min, and the vertical distance between the lip of a die lip and the steel belt is 5 cm.
Example 5
Example 1 was repeated, with the difference from example 1 that:
the silane coupling agent containing amino functional groups is KH-602, the diamine is 3,4 ' -diaminodiphenyl ether, the dianhydride is 3,3 ', 4,4 ' -biphenyltetracarboxylic dianhydride (s-BPDA), the doping amount of the heat-conducting filler is 32 wt%, the alternating-current electric field intensity is 1kV/mm, the viscosity of the synthesized polyamic acid resin is 5.0 ten thousand centipoise, the vertical distance between the lip of a die lip and a steel belt is 15cm, and the running speed of the steel belt is 4 m/min.
Example 6
Example 1 was repeated, with the difference from example 1 that:
the silane coupling agent containing amino functional groups is HD-E8133, the heat conducting filler is silicon carbide, the alternating current electric field intensity is 2.5kV/mm, and the running speed of the steel belt is 4 m/min.
Example 7
Example 1 was repeated, with the difference from example 1 that:
the silane coupling agent containing amino functional groups is HD-M8253, the dianhydride is 3,3 ', 4, 4' -diphenyl ether tetracarboxylic dianhydride (ODPA), the doping amount of the heat-conducting filler is 32 wt%, the alternating-current electric field intensity is 5kV/mm, the viscosity of the synthesized polyamide acid resin is 5.0 ten thousand centipoise, the vertical distance between the lip of the die lip and the steel strip is 15cm, and the running speed of the steel strip is 10M/min.
Example 8
Example 1 was repeated, with the difference from example 1 that:
the silane coupling agent containing amino functional groups is HD-M8252, the doping amount of the heat-conducting filler is 25 wt%, the alternating-current electric field intensity is 7.5kV/mm, the viscosity of the synthesized polyamide acid resin is 2.0 ten thousand centipoise, and the speed of a steel strip is 10M/min.
Example 9
Example 1 was repeated, with the difference from example 1 that:
the silane coupling agent containing amino functional groups is HD-M8132, the alternating current electric field intensity is 1kV/mm, and the running speed of the steel strip is 10M/min.
Comparative example 1
Example 1 was repeated, with the difference from example 1 that:
and (2) no electric field is generated, hot air is not applied to the back surface of the steel belt, the vertical distance between the die lip and the steel belt is 0.2cm, and the synthesized polyamic acid resin is added with triphenyl phosphite serving as a release agent, wherein the addition amount of triphenyl phosphite is 0.1 percent of the weight of the polyamic acid resin (including all solids and solvents in the resin).
Comparative example 2
Example 1 was repeated, with the difference from example 1 that:
the electric field strength is 0.9 kV/mm.
Comparative example 3
Example 1 was repeated, with the difference from example 1 that:
the electric field strength is 11 kV/mm.
Comparative example 4
Example 1 was repeated, with the difference from example 1 that:
the resulting self-supporting film was longitudinally stretched (80 ℃ C.), and then transversely stretched (350 ℃ C.), and the longitudinal/transverse stretching ratio was 1.05.
Comparative example 5
Example 1 was repeated, with the difference from example 1 that:
the back of the steel strip is not blown by hot air.
Comparative example 6
Example 1 was repeated, with the difference from example 1 that:
the vertical distance between the lip of the die lip and the steel belt is 4 cm.
Comparative example 7
Example 1 was repeated, with the difference from example 1 that:
the vertical distance between the lip of the die lip and the steel strip is 18 cm.
The main parameters in the examples and comparative examples described above are collated in Table 1 below.
Table 1:
Figure BDA0002802368540000071
the self-supporting films (i.e., polyamic acid films) prepared in the above examples and comparative examples were examined for releasability and polyimide film properties, and the results are shown in table 2 below.
Table 2:
Figure BDA0002802368540000072
Figure BDA0002802368540000081
note: the tensile strengths in Table 2 were tested using a universal tensile machine, in particular with reference to the standard GB/T13542.2-2009.
The electrical strength test method in Table 2 is referred to the standard GB/T13542.2-2009.
The out-of-plane thermal conductivity and in-plane thermal conductivity in table 2 were tested according to ASTM D5470.
The easy peeling in table 2 means that the self-supporting film has no obvious adhesion when being peeled from the steel strip, and the self-supporting film can be completely peeled from the steel strip; the difficulty in peeling means that the self-supporting film is not completely peeled from the steel strip because the self-supporting film has a large adhesion when peeled from the steel strip.
As can be seen from the data in table 2, the polyimide film prepared by the method of the present invention has high out-of-plane thermal conductivity and in-plane thermal conductivity, and also has good electrical and mechanical properties, and the obtained self-supporting film can be easily peeled from the support without adding a release agent.

Claims (10)

1. A preparation method of a polyimide film with high out-of-plane thermal conductivity coefficient comprises the following steps:
1) obtaining polyamic acid resin doped with heat-conducting filler modified by silane coupling agent containing amino functional group, and defoaming to obtain defoaming polyamic acid resin;
2) casting the obtained defoaming polyamic acid resin on a support body by a film casting extrusion device, and removing partial solvent by a casting furnace to obtain a self-supporting film; wherein, the support body is supported by a front roller and a rear roller and is driven to pass through the casting furnace;
3) imidizing the self-supporting film to obtain the polyimide film with the high out-of-plane thermal conductivity coefficient;
it is characterized in that the utility model is characterized in that,
in the step 2), the defoaming polyamic acid resin is acted by an electric field in the process of extruding from a die lip of a die head of film casting extrusion equipment to fall to a support body, and the direction of the electric field is vertical to the falling direction of the defoaming polyamic acid resin; and applying hot air which faces upwards and is over against the back surface of the support body between the front roller and the rear roller, wherein the temperature of the hot air is 150-170 ℃.
2. The method according to claim 1, wherein in the step 2), the intensity of the electric field is 1 to 10 kV/mm.
3. The method according to claim 1, wherein in step 2), the distance between the lip of the die lip and the support is not less than 5 cm.
4. The method according to claim 1, wherein in the step 2), the distance between the lip of the die lip and the support is 5 to 15 cm.
5. The method according to claim 1, wherein in the step 2), the support is moved at a speed of 4 to 10 m/min.
6. The process according to any one of claims 1 to 5, wherein in step 1), the amino-functional silane coupling agent is one or a combination of two or more selected from KH-550, KH-540, KH-792, KH-602, HD-M8372, HD-E8133, HD-M8253, HD-M8252 and HD-M8132.
7. The method according to any one of claims 1 to 5, wherein in step 1), the thermally conductive filler is one or a combination of two or more selected from boron nitride, aluminum nitride and silicon carbide.
8. The method according to any one of claims 1 to 5, wherein the amount of the thermally conductive filler added in step 1) is 25 to 40% by weight based on the total weight of the thermally conductive filler, the diamine and the dianhydride which form the polyamic acid resin.
9. The method according to any one of claims 1 to 5, wherein the viscosity of the polyamic acid resin in the step 1) is 20000 to 50000 cp.
10. A high out-of-plane thermal conductivity polyimide film prepared by the method of any one of claims 1 to 9.
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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103194062A (en) * 2013-03-29 2013-07-10 株洲时代电气绝缘有限责任公司 Polyimide film and preparation method thereof

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103194062A (en) * 2013-03-29 2013-07-10 株洲时代电气绝缘有限责任公司 Polyimide film and preparation method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
HONG-BAEK CHO，TADACHIKA NAKAYAMA，ETAL.: "Insulating polymer nanocomposites with high-thermal-conduction", 《COMPOSITES SCIENCE AND TECHNOLOGY》 *

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