CN116925405B

CN116925405B - Intrinsic high-heat-conductivity low-dielectric-loss crystalline polyimide film and preparation method thereof

Info

Publication number: CN116925405B
Application number: CN202310939953.3A
Authority: CN
Inventors: 王旭; 王欣; 刘向阳; 刘书言; 韩昊宇; 刘洋; 罗龙波; 刘昌莉
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2023-07-28
Filing date: 2023-07-28
Publication date: 2024-01-23
Anticipated expiration: 2043-07-28
Also published as: CN116925405A

Abstract

The preparation method of the intrinsic high-heat-conductivity low-dielectric-loss crystalline polyimide film comprises the following steps: diamine monomer containing benzene ring conjugated structure and dianhydride monomer are polymerized, diamine monomer containing dynamic bond structure is used as raw material to prepare polyamide acid solution with solid content of 5-25 wt%; and adding a catalyst A and a catalyst B into the polyamic acid solution to form a blending solution, and carrying out tape casting and heating to obtain the crystalline polyimide film. According to the invention, by introducing a trace or small amount (less than or equal to 20%) of diamine containing a dynamic bond structure, polyimide molecular chains are endowed with the characteristic of dynamic bonds, polyamide acid molecular chains have stronger motion capability in the imidization process, the crystallinity of the polymer film is greatly improved, and then the intrinsic thermal conductivity of the polyimide film is improved, and extremely low high-frequency low-dielectric loss performance is obtained; the polymer maintains the intrinsic excellent properties (high strength, high modulus, high thermal stability, etc.).

Description

Intrinsic high-heat-conductivity low-dielectric-loss crystalline polyimide film and preparation method thereof

Technical Field

The invention relates to the technical field of polymer film materials, in particular to an intrinsic high-heat-conductivity low-dielectric-loss crystalline polyimide film and a preparation method thereof.

Background

In recent years, the electronic and electrical industry has been rapidly developed. The dramatic decrease in product size and increase in power density makes heat dissipation an important issue. Polymers have received much attention in terms of thermal interface materials and electronic packaging due to their excellent mechanical toughness, light weight, good chemical stability and high electrical insulation. However, the low thermal conductivity (k. Apprxeq. 0.1-0.2 (W/mK)) of the polymer does not meet the heat dissipation requirements. Generally, a method of improving the thermal conductivity of a polymer is to introduce a thermally conductive filler such as Boron Nitride (BN), aluminum nitride (AlN), carbon Nanotubes (CNTs) and the like into the polymer, but in order to obtain high thermal conductivity, a highly loaded thermally conductive filler (> 30 vol%) is generally required, which is always at the expense of reduced mechanical properties. At the same time, while this approach results in improved thermal conductivity of the composite, the low thermal conductivity of the polymer ultimately limits the overall thermal conductivity.

Calculations have shown that if the thermal conductivity of the polymer matrix is greater than 1 (W/mK), the thermal conductivity of the composite is more likely to increase above 20 (W/mK). Therefore, the Polyimide (PI) with a regular molecular chain structure is constructed to obtain higher intrinsic heat conduction performance, and the polyimide has more practical significance for expanding the application of polyimide in the field of electronic devices. For low dielectric loss performance at high frequencies, the subject group has been studied to demonstrate that by constructing polyimides of liquid crystal like structure, the intermolecular interactions are enhanced, and the rotation of the dipoles can be limited and slowed down, thereby reducing their dielectric loss. It has been found that improving the intrinsic thermal conductivity of polyimide is identical to reducing its dielectric loss at high frequencies, i.e. both require a regular molecular chain structure. The more regular the structure of the molecular chain is, the more likely the heat conducting property of polyimide is improved; the stronger the interactions between the molecular chains of the polyimide, the less likely the molecular chains will move, the weaker the "friction" between the molecular chains, the less likely the rotation of the dipole will occur, and the lower will be the dielectric loss at high frequencies. Therefore, by constructing a polyimide film with high crystallinity, it is advantageous to simultaneously improve the intrinsic thermal conductivity of PI and the low dielectric loss property at high frequencies.

Disclosure of Invention

The invention aims to provide an intrinsic high-heat-conductivity low-dielectric-loss crystalline polyimide film and a preparation method thereof, aiming at the defect of low intrinsic heat conductivity of the existing polymer. By introducing a small amount (less than or equal to 20%) of diamine containing dynamic bond structures such as siloxane, ester bonds or boric acid ester bonds, the polyimide molecular chain is endowed with the characteristic of dynamic bonds, the polyamic acid molecular chain has stronger motion capability in the imidization process, the crystallinity of the polymer film is greatly improved, and then the intrinsic thermal conductivity of the polyimide film is improved, and extremely low high-frequency low-dielectric loss performance is obtained.

In order to achieve the above object, the present invention provides an intrinsic high thermal conductivity low dielectric loss crystalline polyimide film and a method for preparing the same, comprising the steps of:

s1, 9.7-14.7 parts of diamine monomer containing a benzene ring conjugated structure, 1-10 parts of diamine monomer containing a dynamic bond structure, 0-8 parts of diamine monomer containing a benzene ring and a nitrogen atom structure and 10-15 parts of dianhydride monomer are dissolved in 100-150 parts of polar aprotic solvent for polymerization reaction to obtain a polyamide acid solution with the solid content of 5-25 wt%; preferably, the polymerization is carried out in an inert environment, and the addition amount of diamine containing dynamic bond structure is preferably 0.05% -5% of the mole number of dianhydride monomer;

s2, when diamine monomer containing benzene ring and nitrogen atom structure is not adopted in the step S1, adding a catalyst A and a catalyst B into the polyamic acid solution to form a blending solution, and casting the blending solution on a clean substrate to form a film; when diamine monomer containing benzene ring and nitrogen atom structure is adopted in the step S1, the polyamic acid solution is cast on a clean substrate to form a film; finally, carrying out post-treatment on the formed film, and removing the solvent through heating to obtain a crystalline polyimide film with the thickness of 20-100 mu m;

in the steps, the diamine monomer containing a dynamic bond structure is 0.5-10% of the diamine monomer containing a benzene ring conjugated structure in terms of mole number, the catalyst A is 5-50% of the diamine monomer containing a dynamic bond structure, and the catalyst B is 5-50% of the diamine monomer containing a dynamic bond structure;

catalyst a comprises monomers containing one or more of the following structures:

the catalyst B is monohydric alcohol or polyhydric alcohol containing hydroxyl, and has the following structural formula:

R-OH

wherein R is an alkane containing 1 to 8C.

As a further preferable technical scheme of the invention, the diamine monomer containing the benzene ring conjugated structure comprises one or more of 2,2' -bis (trifluoromethyl) -4,4' -diaminobiphenyl (TFMB), 4' -diphenyl ether diamine (ODA), p-Phenylenediamine (PDA), 2- (4-aminophenyl) -5-aminobenzene benzimidazole (PABZ) and 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA), and the structural formula of each diamine monomer is as follows:

as a further preferable embodiment of the present invention, the dianhydride monomer includes rigid dianhydrides containing ester groups such as pyromellitic dianhydride (PMDA), p-phenylene-bis-trimellitate dianhydride (TAHQ), biphenyl tetracarboxylic dianhydride (BPDA), 3', one or more of 4,4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), 4-diphenyl ether dianhydride (ODPA), 4'- (4, 4' -isopropyl diphenoxy) bis (phthalic anhydride) (BPADA) and 3, 4-diphenyl sulfone tetracarboxylic dianhydride (DSDA), and the structural formula of each dianhydride monomer is as follows:

as a further preferable technical scheme of the invention, the diamine monomer containing a dynamic bond structure is a diamine monomer containing a siloxane bond, a lipid bond or a boric acid ester bond, and the diamine monomer containing a dynamic bond structure comprises at least one of the following structures:

as a further preferable technical scheme of the invention, the diamine monomer containing benzene ring and nitrogen atom structure comprises one or more of the following diamines:

as a further preferable embodiment of the present invention, the polar aprotic solvent is any one of N-methylpyrrolidone, N '-dimethylacetamide, and N, N' -dimethylformamide.

As a further preferable technical scheme of the invention, the polymerization or copolymerization temperature is 0-25 ℃, and the total reaction time is 6-8h.

As a further preferable technical scheme of the present invention, in step S2, the process of heating to remove the solvent and complete thermal imidization is as follows: gradually or in one step heating from room temperature to 280-400 ℃ at a heating rate of 2-7 ℃/min, and keeping the temperature at the highest temperature by 0.5-4 h.

The intrinsic high-heat-conductivity low-dielectric-loss crystalline polyimide film and the preparation method thereof can achieve the following beneficial effects by adopting the technical scheme:

the intrinsic high-heat-conductivity low-dielectric-loss crystalline polyimide film provided by the invention has the advantages that the introduction of a trace or a small amount of dynamic bonds does not damage the rigid structure of the original polyimide system, so that the movement capability of polyamide acid in imidization is improved on the basis of keeping the original excellent heat resistance (the thermal weight loss temperature is 500-600 ℃), the mechanical property and the chemical stability, the final crystallinity of polyimide is improved, the ordered degree of the system is increased, the scattering in the phonon transmission process is reduced, the intrinsic heat-conductivity of the polyimide film is greatly improved, and the intrinsic in-plane thermal diffusion coefficient is as high as 2-3 mm ² /s, an out-of-plane thermal diffusivity of up to 0.95. 0.95 mm ² /s。

The preparation method of the intrinsic high-heat-conductivity low-dielectric-loss crystalline polyimide film provided by the invention takes diamine containing a benzene ring conjugated structure, diamine containing dynamic bonds and dianhydride as monomers, the molecular structure of the prepared polyimide contains the dynamic bonds, dynamic fracture and generation can occur at 120-220 ℃ in the presence of a catalyst A and a catalyst B, so that the movement capacity of molecular chains is increased in the process of imidizing polyamide acid by heat treatment, and the crystallinity of the finally obtained polyimide is improved. The molecular chains of the crystalline polyimide film are highly ordered, and the interaction among the molecular chains is enhanced, so that the random motion of the molecular chains is greatly reduced under high frequency, the dielectric loss is greatly reduced, the intrinsic high heat conduction of the film is ensured, the high-frequency low dielectric property is obtained, and the ordered structure of the molecular chains ensures that the dielectric loss of the film is still very low (0.0018) under high frequency (10 GHz).

Drawings

The invention will be described in further detail with reference to the drawings and the detailed description.

FIG. 1 is a spherulitic view of the intrinsic high thermal conductivity low dielectric loss crystalline polyimide film prepared in example 1 under a polarizing microscope;

fig. 2 is a spherulitic view of the intrinsic high thermal conductivity low dielectric loss crystalline polyimide film prepared in example 3 under a polarizing microscope.

The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.

Unless defined otherwise, technical terms used in the following examples have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concepts pertain. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified.

Comparative example 1 (control group of example 1)

Under nitrogen atmosphere, pyromellitic dianhydride (PMDA) and 4,4' -diaminodiphenyl ether (ODA) are taken as raw materials, wherein the mole ratio of PMDA to ODA is 1:1. firstly adding diamine monomer ODA into N-methyl pyrrolidone (NMP), stirring at room temperature for 1h until the diamine monomer ODA is dissolved and dispersed uniformly, then adding dianhydride monomer PMDA, continuously stirring and reacting for 6h to obtain PMDA/ODA polyamide acid solution with the solid content of 12%, mixing and stirring for 2h, standing for deaeration, casting the obtained solution on a clean glass plate substrate, and heating in a vacuum oven, wherein the heating procedure is as follows: 80 ℃ for 2 hours, 150 ℃ for 1 hour, 220 ℃ for 1 hour, and 380 ℃ for 1 hour. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Comparative example 2 (control group of example 2)

Under nitrogen atmosphere, BPADA and ODA are used as raw materials, wherein the mol ratio of BPADA to ODA is 1:1. firstly, adding diamine monomer ODA into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer ODA is dissolved and dispersed uniformly, then adding dianhydride monomer BPADA, and continuing stirring for reacting for 6h h to obtain the polyamide acid solution with the solid content of 15%. Casting the blending solution on a clean glass plate substrate by adopting an automatic film coating machine, and placing the glass plate substrate in a vacuum oven for heating, wherein the heating procedure is as follows: 80 ℃ for 2 hours, 150 ℃ for 1 hour, 220 ℃ for 1 hour, 300 ℃ for 1 hour. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Comparative example 3 (control group of examples 3,4, 5, 6, 7 and 8)

Under the nitrogen atmosphere, TFMB and TAHQ are used as raw materials, wherein the molar ratio of the TFMB to the TAHQ is 1:1. firstly adding diamine monomer TFMB into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer TFMB is dissolved and dispersed uniformly, then adding dianhydride monomer TAHQ, and continuing stirring for reacting for 6h h to obtain the TFMB/TAHQ polyamide acid solution with the solid content of 15%. And casting the blending solution on a clean glass plate substrate by adopting an automatic film coating machine, placing the glass plate substrate in a vacuum oven for heating, and heating to 280-300 ℃ from room temperature in one step, and keeping the temperature constant at 2 h. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Comparative example 4 (control group of example 9)

Under the nitrogen atmosphere, TAHQ and PABZ are used as raw materials, wherein the mol ratio of the TAHQ to the PABZ is 1:1. firstly adding diamine monomer PABZ into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer PABZ is dissolved and dispersed uniformly, then adding dianhydride monomer TAHQ, and continuing stirring for reacting for 6h h to obtain PABZ/TAHQ polyamide acid solution with the solid content of 15%. And casting the blending solution on a clean glass plate substrate by adopting an automatic film coating machine, placing the glass plate substrate in a vacuum oven for heating, and heating to 280-350 ℃ from room temperature in one step, and keeping the temperature constant at 2 h. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Example 1

Under nitrogen atmosphere, PMDA and ODA are used as raw materials, wherein the mole ratio of PMDA to ODA is 1:0.99. adding diamine monomer ODA into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer ODA is dissolved and dispersed uniformly, adding dianhydride monomer PMDA, adding 0.01 BAS monomer into the system after polymerization of 1h, and continuing stirring for reaction for 6h h to obtain a polyamide acid solution of diamine (BAS) with a solid content of 12% and a copolymerization 1% containing a silica dynamic bond structure. Then adding catalyst A and catalyst B with the mole number of 0.05% -5% of BAS, adopting an automatic film coater to cast the blending solution on a clean glass plate substrate, placing the glass plate substrate in a vacuum oven for heating, heating to 380-400 ℃ from room temperature in one step, and keeping the temperature constant for 2 h. Finally, the PI-1 film is obtained. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1. The spherulites of the resulting product under a polarizing microscope are shown in FIG. 1. As can be seen from FIG. 1, the product of example 1 was clearly seen under a polarizing microscope to have a black cross extinction phenomenon, indicating that the prepared film had a clear crystallization behavior.

Example 2

Under nitrogen atmosphere, BPADA and ODA are used as raw materials, wherein the mol ratio of BPADA to ODA is 1:0.97. adding diamine monomer ODA into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer ODA is dissolved and dispersed uniformly, adding dianhydride monomer BPADA, adding 0.01 BAS monomer into the system after polymerization of 1h, and continuing stirring for reaction for 6h h to obtain a polyamide acid solution of 1% of diamine (BAS) containing a dynamic silica bond structure, wherein the solid content of the polyamide acid solution is 15%. Then adding catalyst A and catalyst B with the mole number of 0.05% -5% of BAS, adopting an automatic film coater to cast the blending solution on a clean glass plate substrate, placing the glass plate substrate in a vacuum oven for heating, heating from room temperature to 300-350 ℃ in one step, and keeping the temperature constant at 2 h. Finally, the PI-2 film is obtained. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Example 3

Under the nitrogen atmosphere, TFMB and TAHQ are used as raw materials, wherein the molar ratio of the TFMB to the TAHQ is 1:0.99. adding diamine monomer TFMB into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer TFMB is dissolved and dispersed uniformly, adding dianhydride monomer TAHQ, waiting for polymerization of 1h, adding 0.01 BAS monomer into the system, and continuing stirring for reaction for 6h h to obtain a polyamide acid solution of 1% of diamine (BAS) containing a dynamic silica bond structure, wherein the solid content of the polyamide acid solution is 15%. Then adding catalyst A and catalyst B with the mole number of 0.05% -5% of BAS, adopting an automatic film coater to cast the blending solution on a clean glass plate substrate, placing the glass plate substrate in a vacuum oven for heating, heating from room temperature to 280-300 ℃ in one step, and keeping the temperature constant for 2 h. Finally, the PI-3 film is obtained by a continuous heating mode. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1. The spherulites of the resulting product under a polarizing microscope are shown in FIG. 2. As can be seen from FIG. 2, the product of example 3 was clearly seen under a polarizing microscope to have a black cross extinction phenomenon, indicating that the prepared film had a clear crystallization behavior. Of course, example 3 has more spherulites than example 1, and thus example 3 has a higher crystallinity.

Example 4

Under the nitrogen atmosphere, TFMB and TAHQ are used as raw materials, wherein the molar ratio of the TFMB to the TAHQ is 1:0.99. adding diamine monomer TFMB into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer TFMB is dissolved and dispersed uniformly, adding dianhydride monomer TAHQ, polymerizing for 1h, adding diamine (BAS) monomer with a silica dynamic bond structure into the system, and continuing stirring for reacting for 6h h to obtain the polyamide acid solution with the solid content of 15% and copolymerized 1% BAS. Then adding catalyst A and catalyst B with the mole number of 0.05% -5% of BAS, adopting an automatic film coater to cast the blending solution on a clean glass plate substrate, placing the glass plate substrate in a vacuum oven for heating, wherein the heating procedure is as follows: 80 ℃ for 2 hours, 150 ℃ for 1 hour, 220 ℃ for 1 hour, 300 ℃ for 1 hour. Finally, the PI-4 film is obtained through stage temperature rise. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Example 5

Under the nitrogen atmosphere, TFMB and TAHQ are used as raw materials, wherein the molar ratio of the TFMB to the TAHQ is 1:0.98. adding diamine monomer TFMB into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer TFMB is dissolved and dispersed uniformly, adding dianhydride monomer TAHQ, waiting for polymerization of 1h, adding diamine (BAS) monomer with a silica dynamic bond structure into the system, and continuing stirring for reaction for 6h to obtain a polyamide acid solution with 15% solid content and copolymerized 2% BAS. Then adding catalyst A and catalyst B with the mole number of 0.05% -5% of BAS, adopting an automatic film coater to cast the blending solution on a clean glass plate substrate, placing the glass plate substrate in a vacuum oven for heating, heating from room temperature to 280-300 ℃ in one step, and keeping the temperature constant for 2 h. Finally, the PI-5 film is obtained by a continuous heating mode. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Example 6

Under the nitrogen atmosphere, TFMB and TAHQ are used as raw materials, wherein the molar ratio of the TFMB to the TAHQ is 1:0.98. adding diamine monomer TFMB into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer TFMB is dissolved and dispersed uniformly, adding dianhydride monomer TAHQ, waiting for polymerization of 1h, adding diamine (BAS) monomer with a silica dynamic bond structure into the system, and continuing stirring for reaction for 6h to obtain a polyamide acid solution with 15% solid content and copolymerized 2% BAS. Then adding catalyst A and catalyst B with the mole number of 0.05% -5% of BAS, adopting an automatic film coater to cast the blending solution on a clean glass plate substrate, placing the glass plate substrate in a vacuum oven for heating, wherein the heating procedure is as follows: 80 ℃ for 2 hours, 150 ℃ for 1 hour, 220 ℃ for 1 hour, 300 ℃ for 1 hour. Finally, the PI-6 film is obtained through stage temperature rise. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Example 7

Under the nitrogen atmosphere, TFMB and TAHQ are used as raw materials, wherein the molar ratio of the TFMB to the TAHQ is 1:0.97. adding diamine monomer TFMB into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer TFMB is dissolved and dispersed uniformly, adding dianhydride monomer TAHQ, polymerizing for 1h, adding diamine (BAS) monomer containing a silica dynamic bond structure into the system, and continuing stirring for reaction for 6h h to obtain a polyamide acid solution with 15% solid content and copolymerized 3% BAS. Then adding catalyst A and catalyst B with the mole number of 0.05% -5% of BAS, adopting an automatic film coater to cast the blending solution on a clean glass plate substrate, placing the glass plate substrate in a vacuum oven for heating, heating from room temperature to 280-300 ℃ in one step, and keeping the temperature constant for 2 h. Finally, the PI-7 film is obtained by a continuous heating mode. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Example 8

Under the nitrogen atmosphere, TFMB and TAHQ are used as raw materials, wherein the molar ratio of the TFMB to the TAHQ is 1:0.97. adding diamine monomer TFMB into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer TFMB is dissolved and dispersed uniformly, adding dianhydride monomer TAHQ, polymerizing for 1h, adding diamine (BAS) monomer containing a silica dynamic bond structure into the system, and continuing stirring for reaction for 6h h to obtain a polyamide acid solution with 15% solid content and copolymerized 3% BAS. Then adding catalyst A and catalyst B with the mole number of 0.05% -5% of BAS, adopting an automatic film coater to cast the blending solution on a clean glass plate substrate, placing the glass plate substrate in a vacuum oven for heating, wherein the heating procedure is as follows: 80 ℃ for 2 hours, 150 ℃ for 1 hour, 220 ℃ for 1 hour, 300 ℃ for 1 hour. Finally, the PI-8 film is obtained through stage temperature rise. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Example 9

Taking TAHQ, 2- (4-aminophenyl) -5-aminobenzimidazole (PABZ) and diamine monomer (BAS) containing a silicon oxygen dynamic bond structure as raw materials under the nitrogen atmosphere, wherein the mol ratio of the TAHQ, the PABZ and the BAS is 1:0.5:0.5. Firstly adding diamine monomer PABZ into N-methyl pyrrolidone, stirring at room temperature for 1h until the diamine monomer PABZ is dissolved and dispersed uniformly, then adding dianhydride monomer TAHQ, waiting for polymerization for 1h, then adding BAS monomer into the system, and continuing stirring for reaction for 6h h to obtain the copolyamide acid solution with the solid content of 15%. And casting the blending solution on a clean glass plate substrate by adopting an automatic film coating machine, placing the glass plate substrate in a vacuum oven for heating, and heating to 280-350 ℃ from room temperature in one step, and keeping the temperature constant at 2 h. Finally, the PI-9 film is obtained by a continuous heating mode. The crystallinity, heat conductivity and dielectric properties of the specific films are shown in Table 1.

Further, on the basis of example 9, the PABZ was replaced with another diamine monomer having a benzene ring and a nitrogen atom structure, and the obtained crystalline polyimide film had the following properties as compared with the product of comparative example 4: the crystallinity is obviously improved, dielectric loss is greatly reduced under high frequency, and the high-frequency low-dielectric property can be obtained while the intrinsic high heat conduction of the film is ensured.

Example 10

As a reference example, only the silicon-oxygen bond in the molecular chain of the example 3 is replaced by a boric acid ester bond structure, diamine with the boric acid ester bond structure is used as a diamine monomer with a dynamic bond structure in the preparation method, the rest preparation processes are completely the same as those of the example 3, and the crystallinity of the finally obtained polyimide film is 35 percent, and compared with the comparative example 3, the crystallinity is obviously improved. Meanwhile, the in-plane thermal conductivity of the film was 3.5W/(mK), the out-of-plane thermal conductivity was 0.1W/(mK), the dielectric loss (Df) at 10 GHz frequency was 0.0019, and the dielectric constant (Dk) was 3.15, indicating that the effect of introducing such dynamic bond of the borate bond was consistent with that of the silicon oxygen bond.

Further, only the silicon-oxygen bond in the molecular chain of example 3 was replaced with a lipid bond structure, and the diamine having a lipid bond structure was used as the diamine monomer having a dynamic bond structure in the preparation method. The crystallinity of the finally obtained polyimide film is also significantly improved compared with comparative example 3, indicating that the effect of introducing a dynamic bond such as a lipid bond is consistent with that of a silicon-oxygen bond. It can be seen that in the system of the present invention, the regulation of the regularity of the molecular chain by introducing a dynamic bond into the molecular chain is a method having universality.

TABLE 1

From the contents of Table 1, comparative example 1 is a PMDA-ODA system, comparative example 2 is a BPADA-ODA system, comparative example 3 is a TAHQ-TFMB system, and comparative example 4 is a TAHQ-PABZ system.

Example 1 was a system in which 1% of dynamic bond was introduced into the original system in comparative example 1, example 2 was a system in which 1% of dynamic bond was introduced into comparative example 2, examples 3 and 4 were a system in which 1% of dynamic bond was introduced into comparative example 3, examples 5 and 6 were a system in which 2% of dynamic bond was introduced into comparative example 3, examples 7 and 8 were a system in which 3% of dynamic bond was introduced into comparative example 3, and example 9 was a system in which diamine monomer (PABZ) having a benzene ring and nitrogen atom structure was introduced to catalyze dynamic Bond (BAS) while no catalyst A, B was added.

As can be seen from Table 1, example 1 has 5% increased crystallinity compared to comparative example 1, indicating that the incorporation of dynamic bonds favors the ordered arrangement of molecular chains, while example 1 has 0.3 (W/mK) increased in-plane thermal conductivity and 57% reduced Df compared to comparative example 1; example 2 increased the crystallinity by 4% compared to comparative example 2, indicating that the incorporation of dynamic bonds favors the regular arrangement of molecular chains, while example 1 increased the in-plane thermal conductivity by 0.1 (W/mK) compared to comparative example 1, reduced Df by 17%, given that BPADA had more ether linkages, the molecular chains were more flexible, and the molecular chains themselves tended to be randomly arranged, so the incorporation of 1% dynamic bond promotion was less pronounced than in example 1; examples 3,4, 5, 6, 7, 8 have 30%, 23%, 28%, 21%, 23% and 15% increased crystallinity, respectively, over comparative example 3, indicating that the introduction of dynamic bonds favors the ordered arrangement of molecular chains, while examples 3,4, 5, 6, 7, 8 have 2.4, 2, 2.1, 1.5, 1.4, 0.6 (W/mK) increased in-plane thermal conductivity over comparative example 3, with Df reduced by 64%, 60%, 58%, 54% and 56%, respectively, over comparative example 3; example 9 has an increased crystallinity of 10% compared to comparative example 4, indicating that the incorporation of dynamic bonds favors the ordered arrangement of molecular chains, while example 9 has an increased in-plane thermal conductivity of 0.5 (W/mK) and a 25% decrease in Df compared to comparative example 4.

While particular embodiments of the present invention have been described above, it will be appreciated by those skilled in the art that these are merely illustrative, and that many variations or modifications may be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined only by the appended claims.

Claims

1. The preparation method of the intrinsic high-heat-conductivity low-dielectric-loss crystalline polyimide film is characterized by comprising the following steps of:

s1, 9.7-14.7 parts of diamine monomer containing a benzene ring conjugated structure, 1-10 parts of diamine monomer containing a dynamic bond structure and 10-15 parts of dianhydride monomer are dissolved in 100-150 parts of polar aprotic solvent for polymerization reaction to obtain a polyamide acid solution with the solid content of 5-25 wt%;

s2, adding a catalyst A and a catalyst B into the polyamic acid solution to form a blending solution, and casting the blending solution on a clean substrate to form a film; finally, carrying out post-treatment on the formed film, and removing the solvent through heating to obtain a crystalline polyimide film with the thickness of 20-100 mu m;

in the steps, the diamine monomer containing a dynamic bond structure is 0.5% -10% of the diamine monomer containing a benzene ring conjugated structure in terms of mole number, the catalyst A is 0.05% -5% of the diamine monomer containing a dynamic bond structure, and the catalyst B is 0.05% -5% of the diamine monomer containing a dynamic bond structure;

catalyst a comprises monomers containing one or more of the following structures: the method comprises the steps of carrying out a first treatment on the surface of the The catalyst B is monohydric alcohol containing hydroxyl, and has the following structural formula:

wherein R is an alkyl group having 1 to 8C;

the diamine monomer containing the benzene ring conjugated structure comprises one or more of 2,2' -bis (trifluoromethyl) -4,4' -diaminobiphenyl, 4' -diphenyl ether diamine, p-phenylenediamine and 9, 9-bis (3-fluoro-4-aminophenyl) fluorene;

the diamine monomer containing dynamic bond structure comprises at least one of the following structures:

。

2. the method for preparing an intrinsic high thermal conductivity low dielectric loss crystalline polyimide film according to claim 1, wherein the dianhydride monomer comprises rigid dianhydride containing ester groups, biphenyl tetracarboxylic dianhydride, 3 '; one or more of 4,4' -diphenyl ketone tetracarboxylic dianhydride, 4-diphenyl ether dianhydride, 4'- (4, 4' -isopropyl diphenoxy) bis (phthalic anhydride) and 3, 4-diphenyl sulfone tetracarboxylic dianhydride.

3. The method for preparing an intrinsic high thermal conductivity low dielectric loss crystalline polyimide film according to claim 1, wherein the polar aprotic solvent is any one of N-methylpyrrolidone, N '-dimethylacetamide, N' -dimethylformamide.

4. The method for preparing the intrinsic high-thermal-conductivity low-dielectric-loss crystalline polyimide film according to claim 1, wherein the polymerization temperature is 0-25 ℃, and the total reaction time is 6-8h.

5. The method for preparing the intrinsic high thermal conductivity low dielectric loss crystalline polyimide film according to claim 1, wherein in step S2, the process of heating to remove the solvent and complete thermal imidization is as follows: gradually or in one step heating from room temperature to 280-400 ℃ at a heating rate of 2-7 ℃/min, and keeping the temperature at the highest temperature by 0.5-4 h.

6. The method for producing an intrinsic high thermal conductivity low dielectric loss crystalline polyimide film according to claim 1, wherein in step S1, the diamine having a dynamic bond structure is added in an amount of 0.05 to 5% by mole of the dianhydride monomer.

7. An intrinsic high thermal conductivity low dielectric loss crystalline polyimide film prepared by the method for preparing an intrinsic high thermal conductivity low dielectric loss crystalline polyimide film according to any one of claims 1 to 6.