Black matt ultrathin polyimide film

Abstract

The invention discloses a black matting ultrathin polyimide film, the thickness of the black matting ultrathin polyimide film is 2-12 [mu] m, polyimide accounts for 77-96 wt% of the film, the polyimide is a polyimide precursor formed by polymerizing aromatic dianhydride and aromatic diamine, the aromatic diamine at least comprises a pair of phenylenediamine, the content of the phenylenediamine accounts for 7-40 mol% of the total aromatic diamine, and the content of the aromatic diamine accounts for 10-20 mol% of the total aromatic diamine. Performing chemical cyclization on the polyimide precursor to obtain polyimide; carbon black accounting for 2-8 wt% of the film; the average particle size of the hollow silicon dioxide powder is smaller than 1.5 micrometers, the density of the hollow silicon dioxide powder is smaller than 0.7 g / cm < 3 >, and the hollow silicon dioxide powder accounts for 2-15 wt% of The black ultrathin matt polyimide film has the 60-degree glossiness of less than 30 and the elongation of more than 15%. The thickness is 2-12 [mu] m, the thickness can be thinner to 2-7 [mu] m, and the thermal expansion coefficient is less than 30 ppm / DEG C.

Description

Technical Field

[0001] This application relates to the technical field of polyimide films, and specifically relates to a black matte ultra-thin polyimide film. Background Art

[0002] Polyimide films are commonly used as the cover layer of flexible circuit boards. Among them, black matte polyimide films are commonly used in flexible board applications due to their special optical properties.

[0003] Black matte polyimide films can shield electronic circuits and improve the aesthetics of products, and are widely used in the flexible circuit boards of consumer electronic products, such as smart phones, smart watches, etc.

[0004] However, for known black matte polyimide films, carbon black is mainly used as a pigment, dye, etc. to reduce the light transmittance to achieve the functions of covering and protecting; in addition, a matting agent is contained to scatter light to reduce the visual discomfort caused by the film reflection.

[0005] Currently, the main matting agents commonly used for black matte polyimide films are silica and polyimide particles. When producing polyimide films with a low gloss (less than 30), the matting agent needs to be added to a certain weight ratio to produce sufficient matting effect. However, adding a large amount of particles as a matting agent in the polyimide film will reduce the proportion of the continuous surface of the polyimide material itself, thus significantly reducing its elongation rate.

[0006] Especially when manufacturing a low-gloss ultra-thin polyimide film (thickness less than 12 μm), the matting agent will reduce the elongation rate of the polyimide film, resulting in extremely low tensile strength that the polyimide film can withstand, lack of ductility and easy fracture.

[0007] US840315B2 proposes a black matte polyimide film using silica as a matting agent. Since silica has a relatively high density (2 - 4.5 g / cm 3 ), it has a smaller volume under the same weight addition ratio, so a certain amount needs to be added to achieve the low-gloss effect, which may cause structural defects on the ultra-thin film and also affect the elongation rate.

[0008] To solve the above problems, this application proposes a black matte ultra-thin polyimide film with excellent elongation rate and maintaining a low gloss. Summary of the Invention

[0009] To solve the above deficiencies in the art, this application aims to provide a black matte ultra-thin polyimide film with a thickness of 2 - 12 μm;

[0010] Among them, polyimide accounts for 77-96 wt% of the film. The polyimide is formed by polymerizing an aromatic dianhydride and an aromatic diamine to form a polyimide precursor, and the polyimide precursor is then chemically cyclized to obtain polyimide;

[0011] Carbon black, which accounts for 2-8 wt% of the film;

[0012] Hollow silica powder with an average particle size of less than 1.5 μm and a density of less than 0.7 g / cm 3 , accounting for 2-15 wt% of the film;

[0013] The black matte polyimide film has a glossiness of less than 30 at 60 degrees and an elongation greater than 15%.

[0014] The ultra-thin polyimide film of the present application has a thickness of 2-12 μm, and can be thinner to 2-7 μm, and its coefficient of thermal expansion is less than 30 ppm / °C. Detailed Description of the Embodiments

[0015] The technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative work belong to the scope of protection of the present application.

[0016] It should be particularly noted that similar replacements and modifications made to the present application are obvious to those skilled in the art, and they are all considered to be included in the present application. Relevant personnel can obviously make changes or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present application to implement and apply the technology of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0017] If the present application does not specify specific conditions, they are all carried out according to conventional conditions or conditions recommended by the manufacturer. The raw materials or auxiliary materials used, and the reagents or instruments used without indicating the manufacturer can be obtained as conventional products through commercial purchase.

[0018] The present application will be described in detail below.

[0019] The ultra-thin black matte polyimide film of the present application has a thickness of 2-12 μm, and it includes: polyimide, which accounts for 77-96 wt% of the film. The polyimide is formed by polymerizing an aromatic dianhydride and an aromatic diamine to form a polyimide precursor, and the polyimide precursor is then chemically cyclized to obtain polyimide;

[0020] Carbon black, which accounts for 2-8 wt% of the film;

[0021] Hollow silica powder, with an average particle size of less than 1.5 μm and a density of less than 0.7 g / cm 3 , accounting for 2-15 wt% of the film;

[0022] And the polyimide film has a glossiness of less than 30 at 60 degrees and an elongation greater than 15%.

[0023] The aromatic diamine includes at least p-phenylenediamine (PDA), and its content accounts for 7-40 mol% of the total aromatic diamine. The polyimide film has a coefficient of thermal expansion of less than 30 ppm / °C.

[0024] Preparation of polyimide precursor:

[0025] The polyimide precursor is composed of an aromatic dianhydride and an aromatic diamine.

[0026] At least one of the aforementioned aromatic diamines is p-phenylenediamine (PDA), and the addition amount of p-phenylenediamine is 7-40 mol% of the total molar number of diamines.

[0027] As a solvent, dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), γ-butyrolactone (GBL), N,N-dimethylformamide (DMF) can be used for the preparation of the polyimide precursor. In this application, dimethylacetamide is used as the solvent.

[0028] Preparation of black slurry:

[0029] Carbon black and dimethylacetamide are configured into a solution at a weight ratio of 1:7, stirred evenly, and then oscillated with an ultrasonic oscillator for 1 hour to complete the black slurry.

[0030] The carbon black in the aforementioned black slurry is insulating carbon black.

[0031] The weight ratio of carbon black to dimethylacetamide in the aforementioned black slurry can be adjusted as needed. The weight ratio of carbon black is related to the penetration. The carbon black addition amount range in this application accounts for 2-8 wt% of the black polyimide film.

[0032] Preparation of matting slurry

[0033] Hollow silica powder and dimethylacetamide are configured into a solution at a weight ratio of 1:9, stirred evenly, and then oscillated with an ultrasonic oscillator for 2 hours to complete the matting slurry.

[0034] For the hollow silica powder of the aforementioned matting paste, the applicable range of its density can be between 0.2 and 0.7 g / cm 3 .

[0035] For the hollow silica powder of the aforementioned matting paste, the average particle size is 0.2 - 1.5 μm.

[0036] The weight ratio of the hollow silica powder to dimethylacetamide in the aforementioned matting paste can be adjusted as needed. The weight ratio of the hollow silica powder is related to the gloss and elongation. If the proportion of the hollow silica powder is too small, the gloss of the black matte polyimide film will increase; if the proportion of the hollow silica powder is too large, the elongation will be poor.

[0037] Fabrication of the black matte ultra-thin polyimide film:

[0038] Mix the aforementioned black paste, matting paste and polyimide precursor, stir evenly, then add a catalyst and a dehydrating agent for chemical cyclization. The dehydrating agent can be acetic anhydride or benzoic anhydride, and acetic anhydride is selected as the dehydrating agent in this application; the catalyst can be pyridine, 3-methylpyridine, 2-methylpyridine, 4-methylpyridine, isoquinoline, quinoline, triethylamine, and preferably pyridine, 3-methylpyridine, 2-methylpyridine, 4-methylpyridine. 3-methylpyridine is selected as the catalyst in this application.

[0039] The above-mentioned catalyst and dehydrating agent can be used alone, or can be mixed with a solvent for dilution and then added to the mixture. The mixture mixed with the dehydrating agent and the catalyst is defoamed using a centrifugal defoamer after being stirred evenly, and the defoamed solution is coated on a glass substrate and then coated using a doctor blade. The coated sample is placed in an oven at 80 °C and baked for 20 minutes, then heated to 170 °C and baked for 20 minutes, and then heated to 350 °C and baked for 20 minutes as the final treatment. After baking, the glass is placed in water, and the film can be removed to obtain the black matte polyimide film.

[0040] For the substrate in the above film-making process, in addition to glass, a metal plate can also be used. When using a metal plate to fabricate the black ultra-thin matte polyimide film, it needs to be removed from the metal plate after drying in an oven at 80 °C. The semi-dry film after removal is fixed on a metal frame, and then heated to 170 °C and baked for 20 minutes, and then heated to 350 °C and baked for 20 minutes as the final treatment to obtain the black matte polyimide film.

[0041] The thickness of the above-mentioned black ultra-thin matte polyimide film can be 2 μm to 12 μm.

[0042] The above-mentioned black ultra-thin matte polyimide film can be used as a cover film, and the cover film has an adhesive layer and a base film.

[0043] Example

[0044] The present application will be specifically described according to the examples, but the present application is not limited thereto. Furthermore, the details of the raw materials represented by abbreviations in the following examples are presented.

[0045] Raw materials of polyimide

[0046] PMDA: Pyromellitic dianhydride

[0047] PDA: p-Phenylenediamine

[0048] ODA: 4,4'-Diaminodiphenyl ether

[0049] Raw materials of the matting paste

[0050] Low-density silica powder: density of 0.46 g / cm 3 , average particle size of 1.2 μm

[0051] Low-density silica powder: density of 0.62 g / cm 3 , average particle size of 1.7 μm

[0052] Low-density silica powder: density of 0.67 g / cm 3 , average particle size of 1.4 μm

[0053] Low-density silica powder: density of 0.76 g / cm 3 , average particle size of 1.3 μm

[0054] Raw materials of the carbon black paste

[0055] Carbon black: SPECIAL BLACK 4A (SB4A), manufactured by Evonik Corporation

[0056] Solvent

[0057] DMAc: N,N-Dimethylacetamide

[0058] AA: Acetic anhydride

[0059] AP: 3-Methylpyridine

[0060] <Detection method>

[0061] The properties of the composite films obtained in the following examples were measured using the following methods.

[0062] Coefficient of thermal expansion (100°C to 200°C): Measured in accordance with ASTM D696 standard using a Q400 TMA instrument manufactured by TA Instruments. Measure the coefficient of thermal expansion of the polyimide film at 100°C to 200°C, with the heating rate set at 10°C / min. To remove the stress caused by heat treatment, after removing the residual stress through the first measurement, use the result of the second measurement as the actual value.

[0063] Glossiness: Measure the glossiness at 60 degrees using a gloss meter of BYK brand, model micro-TRI-gloss.

[0064] Elongation rate (%): Measured in accordance with ASTM D882 standard using a universal material testing machine of model 10ST manufactured by Tinius Olsen.

[0065] Thickness measurement method: Use a SYLVAC advanced standard electronic gauge to measure the thickness of five different regions and record the average value.

[0066]

Example 1

[0067] Preparation of carbon black slurry

[0068] Prepare a solution by mixing 1 gram of carbon black with 7 grams of DMAc, stir evenly, and then shake it with an ultrasonic oscillator for 1 hour to complete the black slurry.

[0069] Preparation of low-density matting slurry

[0070] Prepare a solution by mixing 1 gram of hollow silica powder with 9 grams of DMAc, stir evenly, and then shake it with an ultrasonic oscillator for 2 hours to complete the matting slurry. The selected hollow silica: density is 0.46 g / cm 3 , and the average particle size is 1.2 μm.

[0071] Preparation of polyimide precursor

[0072] Add 4.05 grams (20 mol%) of PDA to 425 grams of DMAc and stir to mix. After the PDA is completely dissolved, add 30.03 grams of ODA. After it is completely dissolved, slowly add 38.9 grams of PMDA, and control the temperature at 25°C. Stir and react for two hours, and then use a small amount of PMDA to adjust the viscosity. Finally, obtain a polyamic acid solution with a solid content of 15% and a viscosity of 161,200 cps. Preparation of black ultra-thin matting polyimide film

[0073] 1.92 g of carbon black slurry, 1.2 g of low-density matting slurry, 40 g of polyamic acid solution and 20 g of DMAc were used to make the produced polyimide film contain 4 wt% of carbon black and 2 wt% of hollow silica powder. After stirring evenly, AA and DMAc were diluted at a weight ratio of 5:1, and then AP and DMAc were diluted at a weight ratio of 1:1. After that, 3.41 mL of AA diluent and 2.89 mL of AP diluent were added respectively. After stirring evenly, a centrifugal degassing machine was used for degassing. The degassed solution was poured on a glass substrate and coated with a doctor blade with a 125 μm gap. The coated sample was placed in an 80 °C oven and baked for 20 minutes, then heated to 170 °C at a rate of 1.8 °C / min and baked for 20 minutes, and then heated to 350 °C at a rate of 2.0 °C / min and baked for 20 minutes as the final treatment.

[0074] The glass substrate was immersed in water, and the black matting polyimide film was peeled off from the glass substrate. The thickness of the film was 6.2 μm.

[0075]

Example 2

[0076] The production of the carbon black slurry was the same as that in Example 1.

[0077] The production of the low-density matting slurry was the same as that in Example 1.

[0078] The production of the polyimide film precursor was the same as that in Example 1.

[0079] The production of the black matting polyimide film was the same as that in Example 1, but 6 g of low-density matting slurry was added to make it contain 10 wt% of hollow silica powder.

[0080] The glass substrate was immersed in water, and the black matting polyimide film was peeled off from the glass substrate. The thickness of the film was 6.7 μm.

[0081]

Example 3

[0082] The production of the carbon black slurry was the same as that in Example 1.

[0083] The production of the low-density matting slurry was the same as that in Example 1.

[0084] The production of the polyimide film precursor was the same as that in Example 1.

[0085] The production of the black matting polyimide film was the same as that in Example 1, but 9 g of low-density matting slurry was added to make it contain 15 wt% of hollow silica powder.

[0086] The glass substrate was immersed in water, and the black matting polyimide film was peeled off from the glass substrate. The thickness of the film was 6.2 μm.

[0087]

Example 4

[0088] The production of the carbon black slurry is the same as that in Example 1.

[0089] The production of the low-density matting slurry is the same as that in Example 1. The hollow silica is changed to: density 0.67 g / cm 3 , and the average particle size is 1.4 μm.

[0090] The production of the polyimide precursor is the same as that in Example 1.

[0091] The production of the black matting polyimide film is the same as that in Example 1, but 9 g of the low-density matting slurry is added, so that the produced polyimide film contains 15 wt% of hollow silica powder.

[0092] The glass substrate is immersed in water, and the black matting polyimide film is peeled off from the glass substrate. The thickness of the film is 6.0 μm.

[0093]

Example 5

[0094] The production of the carbon black slurry is the same as that in Example 1.

[0095] The production of the low-density matting slurry is the same as that in Example 1.

[0096] The production of the polyimide precursor is the same as that in Example 1.

[0097] The production of the black matting polyimide film is the same as that in Example 1, but 9 g of the low-density matting slurry is added, so that the produced polyimide film contains 15 wt% of hollow silica powder. Coating is carried out using a doctor blade with a 50-μm gap.

[0098] The glass substrate is immersed in water, and the black matting polyimide film is peeled off from the glass substrate. The thickness of the film is 2.6 μm.

[0099]

Example 6

[0100] The production of the carbon black slurry is the same as that in Example 1.

[0101] The production of the low-density matting slurry is the same as that in Example 1.

[0102] The production of the polyimide precursor

[0103] 1.98 g (10 mol%) of PDA is added to 425 g of DMAc and stirred and mixed. After the PDA is completely dissolved, 33.023 g of ODA is added. After its complete dissolution, 38 g of PMDA is slowly added, and the temperature is controlled at 25 °C. After stirring and reacting for two hours, a small amount of PMDA is used to adjust the viscosity. Finally, a polyamic acid solution with a solid content of 15% and a viscosity of 155,900 cps is obtained.

[0104] The production of the black matte polyimide film is the same as in Example 1, except that 9 grams of low-density matte slurry is added, so that the produced polyimide film contains 15 wt% of hollow silica powder.

[0105] The glass substrate was immersed in water, and the black matte polyimide film was peeled off from the glass substrate. The thickness of the film was 6.5 μm.

[0106]

Example 7

[0107] The production of the carbon black slurry is the same as in Example 1.

[0108] The production of the low-density matte slurry is the same as in Example 1.

[0109] The production of the polyimide precursor is the same as in Example

[0110] 8.036 grams (38 mol%) of PDA was added to 425 grams of DMAc and stirred and mixed. After the PDA was completely dissolved, 24.279 grams of ODA was added. After its complete dissolution, 38.4 grams of PMDA was slowly added, and the temperature was controlled at 25 °C. After stirring and reacting for two hours, a small amount of PMDA was used to adjust the viscosity. Finally, a polyamic acid solution with a solid content of 15% and a viscosity of 161,200 cps was obtained.

[0111] The production of the black matte polyimide film is the same as in Example 1, except that 9 grams of low-density matte slurry is added, so that the produced polyimide film contains 15 wt% of hollow silica powder.

[0112] The glass substrate was immersed in water, and the black matte polyimide film was peeled off from the glass substrate. The thickness of the film was 6.3 μm.

[0113]

Comparative Example 1

[0114] The production of the carbon black slurry is the same as in Example 1.

[0115] The production of the low-density matte slurry is the same as in Example 1.

[0116] The production of the polyimide precursor is the same as in Example 1

[0117] The production of the black matte polyimide film is the same as in Example 1, except that 0.6 grams of low-density matte slurry is added, so that the produced polyimide film contains 1 wt% of hollow silica powder, and a doctor blade with a 100 μm gap is used for coating.

[0118] The glass substrate was immersed in water, and the black matte polyimide film was peeled off from the glass substrate. The thickness of the film was 4.1 μm.

[0119]

Comparative Example 2

[0120] The production of the carbon black slurry is the same as in Example 1.

[0121] The production of the low-density extinction paste is the same as that in Example 1.

[0122] The production of the polyimide precursor is the same as that in Example 1.

[0123] The production of the black extinction polyimide film is the same as that in Example 1, except that 10.2 g of the low-density extinction paste is added, so that the produced polyimide film contains 17 wt% of hollow silica powder, and a doctor blade with a 100-μm gap is used for coating.

[0124] The glass substrate is immersed in water, and the black extinction polyimide film is peeled off from the glass substrate. The thickness of the film is 4.8 μm.

[0125]

Comparative Example 3

[0126] The production of the carbon black paste is the same as that in Example 1.

[0127] The production of the low-density extinction paste is the same as that in Example 1, and the hollow silica is changed to: density 0.62 g / cm 3 , and the average particle size is 1.7 μm.

[0128] The production of the polyimide precursor is the same as that in Example 1.

[0129] The production of the black extinction polyimide film is the same as that in Example 1, except that 9 g of the low-density extinction paste is added, so that the produced polyimide film contains 15 wt% of hollow silica powder, and a doctor blade with a 100-μm gap is used for coating.

[0130] The glass substrate is immersed in water, and the black extinction polyimide film is peeled off from the glass substrate. The thickness of the film is 4.2 μm.

[0131]

Comparative Example 4

[0132] The production of the carbon black paste is the same as that in Example 1.

[0133] The production of the low-density extinction paste is the same as that in Example 1, and the hollow silica is changed to: density 0.76 g / cm 3 , and the average particle size is 1.3 μm.

[0134] The production of the polyimide precursor is the same as that in Example 1.

[0135] The production of the black extinction polyimide film is the same as that in Example 1, except that 9 g of the low-density extinction paste is added, so that the produced polyimide film contains 15 wt% of hollow silica powder, and a doctor blade with a 125-μm gap is used for coating.

[0136] The glass substrate is immersed in water, and the black extinction polyimide film is peeled off from the glass substrate. The thickness of the film is 6.1 μm.

[0137]

Comparative Example 5

[0138] The carbon black slurry was prepared in the same manner as in Example 1.

[0139] The low-density matting slurry was prepared in the same manner as in Example 1.

[0140] The polyimide precursor was prepared in the same manner as in Example 1.

[0141] The black matting polyimide film was prepared in the same manner as in Example 1, except that 9 g of the low-density matting slurry was added to make the resulting polyimide film contain 15 wt% of hollow silica powder, and a doctor blade with a 50-μm gap was used for coating.

[0142] The glass substrate was immersed in water, and the black matting polyimide film was peeled off from the glass substrate. The thickness of the film was 1.3 μm.

[0143]

Comparative Example 6

[0144] The carbon black slurry was prepared in the same manner as in Example 1.

[0145] The low-density matting slurry was prepared in the same manner as in Example 1.

[0146] Preparation of the polyimide precursor

[0147] 0.98 g (5 mol%) of PDA was added to 425 g of DMAc and stirred and mixed. After the PDA was completely dissolved, 34.47 g of ODA was added. After its complete dissolution, 37.6 g of PMDA was slowly added, and the temperature was controlled at 25°C. After stirring and reacting for two hours, a small amount of PMDA was used to adjust the viscosity. Finally, a polyamic acid solution with a solid content of 15% and a viscosity of 161,400 cps was obtained.

[0148] The black matting polyimide film was prepared in the same manner as in Example 1, except that 9 g of the low-density matting slurry was added to make the resulting polyimide film contain 15 wt% of hollow silica powder, and a doctor blade with a 100-μm gap was used for coating.

[0149] The glass substrate was immersed in water, and the black matting polyimide film was peeled off from the glass substrate. The thickness of the film was 4.2 μm.

[0150]

Comparative Example 7

[0151] The carbon black slurry was prepared in the same manner as in Example 1.

[0152] The low-density matting slurry was prepared in the same manner as in Example 1

[0153] Preparation of the polyimide precursor

[0154] 8.968 g (42 mol%) of PDA was added to 425 g of DMAc and stirred to mix. After the PDA was completely dissolved, 22.933 g of ODA was added. After its complete dissolution, 40.9 g of PMDA was slowly added, and the temperature was controlled at 25 °C. After stirring and reacting for two hours, a small amount of PMDA was used to adjust the viscosity. Finally, a polyamic acid solution with a solid content of 15% and a viscosity of 169,200 cps was obtained.

[0155] The production of the black matte polyimide film was the same as in Example 1, except that 9 g of low-density matte slurry was added, so that the produced polyimide film contained 15 wt% of hollow silica powder, and a doctor blade with a 100-μm gap was used for coating.

[0156] The glass substrate was immersed in water, and the black matte polyimide film was peeled off from the glass substrate. The thickness of the film was 3.6 μm.

[0157] The comparison table of the examples and comparative examples is as follows:

[0158]

[0159]

[0160] Comparative Example 1: Since the usage amount of hollow silica was less than 2 wt%, its 60-degree glossiness was greater than 30 GU.

[0161] Comparative Example 2: Since the usage amount of the hollow silica it used was greater than 15 wt%, its elongation was less than 15%.

[0162] Comparative Example 3: Since the particle size of the hollow silica it used was greater than 1.5 μm, its elongation was less than 15%.

[0163] Comparative Example 4: Since the density of the hollow silica it used was greater than 0.7 g / cm 3 , its 60-degree glossiness was greater than 30 GU.

[0164] Comparative Example 5: Since the thickness of the polyimide film was less than 2 μm, its elongation was less than 15%.

[0165] Comparative Example 6: Since the usage amount of p-phenylenediamine (PDA) was less than 7 mol%, its thermal expansion coefficient was greater than 30 ppm / °C.

[0166] Comparative Example 7: Since the usage amount of p-phenylenediamine (PDA) was greater than 40 mol%, its elongation was less than 15%.

[0167] As shown in Table 1, it can be confirmed that the black matte ultra-thin polyimide film manufactured according to the examples of the present application can still maintain a high elongation while exhibiting excellent optical properties (60-degree glossiness).

[0168] The key to the better extinction effect shown in the embodiments lies in the selection of hollow silica powder with a lower density and a smaller particle size. When the density is small, it means that the powder has a larger volume at the same weight ratio, so it shows a lower glossiness. Moreover, a smaller particle size can better maintain its elongation rate when producing the film.

[0169] The description of the above embodiments is only used to help understand the method and its core idea of this application. It should be noted that for those of ordinary skill in the art, without departing from the principle of this application, several improvements and modifications can be made to this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A black matte ultra-thin polyimide film, characterized in that, the thickness of the ultra-thin polyimide film is 2 - 12 μm, and the ultra-thin polyimide film comprises: polyimide, accounting for 77 - 96 wt% of the ultra-thin polyimide film; the polyimide is formed by polymerizing an aromatic dianhydride and an aromatic diamine to form a polyimide precursor, and the polyimide precursor is then obtained through chemical cyclization; carbon black, accounting for 2 - 8 wt% of the ultra-thin polyimide film; Hollow silica powder with an average particle size of less than 1.5 μm and a density of less than 0.7 g / cm 3 , accounting for 2-15 wt% of the ultra-thin polyimide film; wherein, the polyimide film has a glossiness of less than 30 at 60 degrees and an elongation greater than 15%.

2. The black matte ultra-thin polyimide film according to claim 1, characterized in that, the thickness of the ultra-thin polyimide film is 2 - 7 μm.

3. The black matte ultra-thin polyimide film according to claim 1, characterized in that, the aromatic diamine at least includes p-phenylenediamine, and the content of p-phenylenediamine accounts for 7 - 40 mol% of the total aromatic diamine.

4. The black matte ultra-thin polyimide film according to claim 1, characterized in that, the thermal expansion coefficient of the polyimide film is less than 30 ppm / °C.

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