Black matting polyimide film

Abstract

The present application discloses a black matting polyimide film, which comprises a polyimide accounting for 71-89 wt% of the film, the polyimide being obtained by chemical cyclization after polymerization of diamine and dianhydride to form polyamic acid; a carbon black accounting for 2-9 wt% of the film, wherein the median particle size (D50) is less than 1 μm; and a polyimide matting agent, wherein the median particle size (D50) is 0.3-4 μm, and the weight percentage of the polyimide matting agent in the film is 9-20 wt%, so that the film has a breaking elongation greater than 15%, a peak height (Spk) less than 300 nm, a 60-degree glossiness less than 30 GU, and a transmittance less than 1%.

Description

Technical Field

[0001] This invention relates to the field of polyimide film technology, and more specifically to a black matte polyimide film. Background Technology

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

[0003] In recent years, with the increasing performance and functionality of electronic devices, there is still a demand for coverings that can maintain electrical insulation properties even at high frequencies, while also retaining acceptable structural and optical properties to provide protection for electronic components and avoid unnecessary visual inspection and damage.

[0004] However, known black matte polyimide films mainly use carbon black as a pigment and dye to reduce light transmittance, thereby achieving the functions of covering and protection. In addition, colored polyimide films, due to their color, will produce a lot of reflected light on their surface, so matting agents are added to reduce the gloss of the film.

[0005] To further reduce the gloss of polyimide films, the size and proportion of the added matting agent particles are crucial factors. Currently, the disclosed particle size range of polyimide matting agents is approximately 2–8 micrometers, and their addition amount is 1.6–9% by weight, achieving a low gloss value of less than 30 at 60 degrees. However, if the matting agent particles are too large, more particles will protrude from the film surface, reducing the film's elongation at break and mechanical strength. This makes the film more prone to cracking during production, lowering yield. Furthermore, the excessive protrusions caused by larger particles will lead to inaccurate thickness measurements during production, significantly reducing overall production quality.

[0006] Furthermore, when large matting agent particles are applied to polyimide films with relatively small thicknesses, the film's elongation at break will decrease, leading to increased brittleness and reduced production yield during the manufacturing process.

[0007] To overcome the problem of excessively large matting agent particles being used in thinner polyimide films, a matting agent with a smaller particle size can be used. This reduces the likelihood of the matting agent protruding from the film surface, improving the film's elongation at break and making film thickness measurement more accurate. However, reducing the size of the matting agent particles may increase the film's gloss, failing to meet the product's low-gloss requirements. To overcome this problem, research on the size and amount of matting agent particles is an important topic in the study of matte polyimide films. Summary of the Invention

[0008] In order to address the aforementioned deficiencies in the field, the present invention aims to provide a black matte polyimide film with high elongation at break and low peak height, and can achieve a low gloss value.

[0009] According to one aspect of the present invention, a black matte polyimide film is provided, comprising a polyimide comprising 71-89 wt% of the film, the polyimide being obtained by chemical cyclization after polymerization of diamine and dianhydride to form polyamic acid; a carbon black comprising 2-9 wt%; and a polyimide matting agent comprising a median particle size of 0.3-4 μm and a median addition amount of 9-20 wt%; wherein the black matte polyimide film has an elongation at break greater than 15%, a peak height (Spk) less than 300 nm, a 60-degree gloss level less than 30 GU, and a transmittance less than 1%. Detailed Implementation

[0010] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] It is particularly important to note that similar substitutions and modifications made to this invention are obvious to those skilled in the art, and they are all considered to be included in this invention. Those skilled in the art will clearly be able to modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments.

[0012] Unless otherwise specified, this invention is carried out under conventional conditions or conditions recommended by the manufacturer. The raw materials or excipients used, as well as the reagents or instruments used, whose manufacturers are not specified, are all conventional products that can be obtained commercially.

[0013] The present invention will now be described in detail.

[0014] The black matte polyimide film of the present invention comprises polyamic acid, a polyimide matting agent, and carbon black. The polyimide matting agent and carbon black are each prepared into a slurry, which is then mixed with polyamic acid and subjected to a chemical cyclization process to cyclize the polyamic acid into polyimide.

[0015] The aforementioned chemical cyclization refers to the cyclization of polyamic acid to form polyimide when a catalyst or dehydrating agent or both are used simultaneously.

[0016] Production of polyamic acid

[0017] Polyamic acid is obtained by polymerizing diamine and dianhydride in an organic solvent.

[0018] The diamine may be selected from p-phenylenediamine (PDA), 4,4'-diaminodiphenyl ether (ODA), 2,2'-dimethyl-4,4'-diaminobiphenyl (mTB), 4,4'-diaminobenzoylaniline (44DABA), 5-amino-2-(4-aminophenyl)benzoxazole (5BPOA), 4,4'-bis(4-aminophenoxy)biphenyl (B3-methylpyridine (AP)B), 4-aminobenzoic acid 4-aminophenyl ester (3-methylpyridine (AP)AB), 1,3-bis(3-aminophenoxy)benzene (3-methylpyridine (AP)BN), 1,4-bis(4-aminophenoxy)benzene (TPEQ), 1,3-bis(4-aminophenoxy)benzene (TPER), and combinations thereof.

[0019] The dianhydride can be selected from pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-(4,4'-isopropylidenediphenoxy)phthalic anhydride (BPADA), 4,4'-oxodiphthalic anhydride (ODPA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TAHQ), and combinations thereof.

[0020] The aforementioned aromatic diamine can be a combination of p-phenylenediamine (PDA) and 4,4'-diaminodiphenyl ether (ODA).

[0021] The aforementioned aromatic dianhydride can be pyromellitic dianhydride (PMDA) or 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA).

[0022] As a solvent, polyamic acid can be prepared using dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), γ-butyrolactone (GBL), and N,N-dimethylformamide (DMF). In this invention, dimethylacetamide is used as a solvent.

[0023] Preparation of carbon black slurry

[0024] Carbon black and dimethylacetamide were mixed in a weight ratio of 1:7 to form a solution. After stirring evenly, the solution was shaken with an ultrasonic vibrator for 1 hour to complete the carbon black slurry.

[0025] The carbon black in the aforementioned carbon black slurry is insulating carbon black.

[0026] The weight ratio of carbon black to dimethylacetamide in the aforementioned carbon black slurry can be adjusted as needed. The weight ratio of carbon black is related to the penetration and dielectric loss factor. If the proportion of carbon black is too high, the dielectric loss factor will increase. The carbon black addition amount in this invention is 2 to 9 wt% of the black polyimide film.

[0027] Preparation of polyimide matting agent slurry

[0028] A polyimide matting agent and dimethylacetamide were prepared into a solution at a weight ratio of 1:9. After stirring evenly, the solution was ground with 0.5μm zirconium beads and a zirconium bead filling rate of 50% by volume. The grinding time was 30 minutes to complete the polyimide matting agent slurry.

[0029] The aforementioned polyimide matting agent includes a first polyimide matting agent and a second polyimide matting agent.

[0030] The median particle size of the aforementioned first polyimide matting agent is between 0.3 and 1 μm.

[0031] The aforementioned first polyimide matting agent accounts for 80-95 wt% of the total polyimide matting agent.

[0032] The median particle size of the aforementioned second polyimide matting agent is between 1 and 4 μm.

[0033] The aforementioned second polyimide matting agent accounts for 5 to 20 wt% of the total polyimide matting agent.

[0034] The weight ratio of polyimide matting agent to dimethylacetamide in the aforementioned polyimide matting agent slurry can be adjusted as needed. The weight ratio of polyimide matting agent is related to gloss and peak height. If the proportion of polyimide matting agent is too small, the gloss of the black matte polyimide film will increase. Conversely, it will cause severe graininess on the film surface, resulting in poor finished product appearance and inflated film thickness measurements.

[0035] Fabrication of black matte polyimide film

[0036] The aforementioned carbon black slurry, polyimide matting agent slurry, and polyamic acid are mixed and stirred evenly. Then, a catalyst and a dehydrating agent are added for chemical cyclization. The dehydrating agent can be acetic anhydride or benzoic anhydride. In this invention, acetic anhydride is selected as the dehydrating agent. The catalyst can be pyridine, 3-methylpyridine, 2-methylpyridine, 4-methylpyridine, isoquinoline, quinoline, or triethylamine. Pyridine, 3-methylpyridine, 2-methylpyridine, and 4-methylpyridine are preferred. In this invention, 3-methylpyridine is selected as the catalyst.

[0037] The catalyst and dehydrating agent mentioned above can be used alone or diluted with a solvent and then added to the mixture. After uniform stirring, the mixture containing the dehydrating agent and catalyst is degassed using a centrifugal degassing machine. The degassed solution is then coated onto a glass substrate using a doctor blade with a 300 μm gap. The coated sample is placed in an 80℃ oven for 20 minutes, then heated to 170℃ for 20 minutes, and finally heated to 350℃ for 20 minutes as the final treatment. After baking, the glass is placed in water, and the film is removed to obtain a black matte polyimide film.

[0038] In addition to glass, metal plates can also be used as substrates in the above film-making process. When using metal plates to make the black matte polyimide film, after baking and drying in an oven at 80°C, the film needs to be removed from the metal plate. The semi-dried film is then fixed on a metal frame. After that, the temperature is raised to 170°C and baked for 20 minutes, and then raised to 350°C and baked for 20 minutes as the final treatment to obtain the black matte polyimide film.

[0039] The aforementioned black matte polyimide film has a thickness of less than 12 μm.

[0040] The thickness of the aforementioned black matte polyimide film is preferably 5μm, 7μm, or 12μm.

[0041] The aforementioned black matte polyimide film can be used as a cover film, which has an adhesive layer and a base layer.

[0042] The technical solution of the present invention will be further described below with reference to specific embodiments, but the present invention is not limited thereto.

[0043] solvent

[0044] Dimethylacetamide (DMAc): Dimethylacetamide

[0045] Acetic anhydride (AA): Acetic anhydride

[0046] 3-Methylpyridine (AP): 3-Methylpyridine

[0047] Production of polyamic acid

[0048] 7.323 g of p-phenylenediamine (PDA) was added to 425 g of dimethylacetamide (DMAc) and stirred. After the p-phenylenediamine (PDA) dissolved, 25.182 g of 4,4'-diaminodiphenyl ether (ODA) was added. After the 4,4'-diaminodiphenyl ether (ODA) dissolved, 1.138 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added. After the BPDA dissolved, 40.724 g of pyromellitic dianhydride (PMDA) was slowly added. The temperature was controlled at 25°C and the reaction was stirred for two hours. The viscosity was adjusted using a small amount of pyromellitic dianhydride (PMDA). Finally, polyamic acid with a solid content of 15% and a viscosity of 223,400 cps was obtained.

[0049] <Detection Method>

[0050] The properties of the composite membranes obtained in the following examples were measured using the following methods.

[0051] Elongation at break: Measured using a Hounsfield H10K-S tensile testing machine in accordance with ASTM D882 specifications.

[0052] Optical transmittance: Measured using an instrument of model NDH-2000N manufactured by Nippon Denshoku in accordance with ISO 14782 standard.

[0053] Gloss: The gloss was measured at 60 degrees and 80 degrees using a BYK micro-TRI-gloss meter.

[0054] Highlight peak height (Spk): Measured using a Zygo Zegage Plus instrument.

[0055]

Example 1

[0056] Preparation of polyimide matting agent slurry

[0057] One gram of the second polyimide matting agent (median particle size: 2.2 μm) and nine grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0058] Preparation of carbon black slurry

[0059] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0060] Fabrication of black matte polyimide film

[0061] 1.637 g of carbon black paste, 5.116 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0062] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 10 μm was peeled off from the glass substrate.

[0063]

Example 2

[0064] Preparation of polyimide matting agent slurry

[0065] One gram of the first polyimide matting agent (median particle size: 0.5 μm) and nine grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0066] Preparation of carbon black slurry

[0067] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0068] Fabrication of black matte polyimide film

[0069] 1.738 g of carbon black paste, 8.148 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0070] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 10 μm was peeled off from the glass substrate.

[0071]

Example 3

[0072] Preparation of polyimide matting agent slurry

[0073] A solution was prepared by mixing 0.81 g of the first polyimide matting agent (median particle size: 0.5 μm), 0.19 g of the second polyimide matting agent (median particle size: 3 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0074] Preparation of carbon black slurry

[0075] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0076] Fabrication of black matte polyimide film

[0077] 1.628 g of carbon black paste, 4.832 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0078] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 9 μm was peeled off from the glass substrate.

[0079]

Example 4

[0080] Preparation of polyimide matting agent slurry

[0081] A solution was prepared by mixing 0.83 g of the first polyimide matting agent (median particle size: 0.5 μm), 0.17 g of the second polyimide matting agent (median particle size: 3 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0082] Preparation of carbon black slurry

[0083] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0084] Fabrication of black matte polyimide film

[0085] 1.647 g of carbon black paste, 5.404 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0086] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 9 μm was peeled off from the glass substrate.

[0087]

Example 5

[0088] Preparation of polyimide matting agent slurry

[0089] A solution was prepared by mixing 0.93 g of the first polyimide matting agent (median particle size: 0.5 μm), 0.07 g of the second polyimide matting agent (median particle size: 3 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0090] Preparation of carbon black slurry

[0091] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0092] Fabrication of black matte polyimide film

[0093] 1.637 g of carbon black paste, 5.116 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0094] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 9 μm was peeled off from the glass substrate.

[0095]

Example 6

[0096] Preparation of polyimide matting agent slurry

[0097] A solution was prepared by mixing 0.85 g of the first polyimide matting agent (median particle size: 0.5 μm), 0.15 g of the second polyimide matting agent (median particle size: 3 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0098] Preparation of carbon black slurry

[0099] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0100] Fabrication of black matte polyimide film

[0101] 1.676 g of carbon black paste, 6.286 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0102] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 9 μm was peeled off from the glass substrate.

[0103]

Example 7

[0104] Preparation of polyimide matting agent slurry

[0105] A solution was prepared by mixing 0.91 g of the first polyimide matting agent (median particle size: 0.5 μm), 0.09 g of the second polyimide matting agent (median particle size: 3 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0106] Preparation of carbon black slurry

[0107] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0108] Fabrication of black matte polyimide film

[0109] 1.320 g of carbon black paste, 9.350 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 700 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0110] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 25 μm was peeled off from the glass substrate.

[0111]

Comparative Example 1

[0112] Preparation of polyimide matting agent slurry

[0113] A solution was prepared by mixing 0.81 g of the first polyimide matting agent (median particle size: 0.5 μm), 0.19 g of the second polyimide matting agent (median particle size: 3 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0114] Preparation of carbon black slurry

[0115] 1 gram of carbon black (median particle size: 2.5 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0116] Fabrication of black matte polyimide film

[0117] 1.628 g of carbon black paste, 4.832 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0118] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 10 μm was peeled off from the glass substrate.

[0119] [Comparative Example 2]

[0120] Preparation of polyimide matting agent slurry

[0121] A solution was prepared by mixing 0.58 g of the first polyimide matting agent (median particle size: 0.5 μm), 0.42 g of the second polyimide matting agent (median particle size: 3 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0122] Preparation of carbon black slurry

[0123] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0124] Fabrication of black matte polyimide film

[0125] 1.628 g of carbon black paste, 4.832 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0126] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 10 μm was peeled off from the glass substrate.

[0127] [Comparative Example 3]

[0128] Preparation of polyimide matting agent slurry

[0129] A solution was prepared by mixing 0.83 g of the first polyimide matting agent (median particle size: 0.5 μm), 0.17 g of the second polyimide matting agent (median particle size: 3 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0130] Preparation of carbon black slurry

[0131] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0132] Fabrication of black matte polyimide film

[0133] 1.530 g of carbon black paste, 1.913 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0134] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 10 μm was peeled off from the glass substrate.

[0135] [Comparative Example 4]

[0136] Preparation of polyimide matting agent slurry

[0137] A solution was prepared by mixing 0.88 g of the first polyimide matting agent (median particle size: 0.05 μm), 0.12 g of the second polyimide matting agent (median particle size: 3 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0138] Preparation of carbon black slurry

[0139] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0140] Fabrication of black matte polyimide film

[0141] 1.738 g of carbon black paste, 8.148 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 300 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0142] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 10 μm was peeled off from the glass substrate.

[0143] [Comparative Example 5]

[0144] Preparation of polyimide matting agent slurry

[0145] A solution was prepared by mixing 0.81 g of the first polyimide matting agent (median particle size: 0.5 μm), 0.19 g of the second polyimide matting agent (median particle size: 7 μm), and 9 g of dimethylacetamide (DMAc). After stirring evenly, the solution was ground with 0.5 μm zirconium beads and a zirconium bead filling rate of 50% by volume to complete the polyimide matting agent slurry.

[0146] Preparation of carbon black slurry

[0147] 1 gram of carbon black (median particle size: 0.4 μm) and 7 grams of dimethylacetamide (DMAc) were mixed to form a solution. After stirring evenly, the solution was shaken with an ultrasonic shaker for 1 hour to complete the carbon black slurry.

[0148] Fabrication of black matte polyimide film

[0149] 1.628 g of carbon black paste, 5.116 g of polyimide matting agent paste, 29.33 g of polyamic acid, and 10.67 g of dimethylacetamide (DMAc) were mixed thoroughly. Acetic anhydride (AA) and dimethylacetamide (DMAc) were diluted at a weight ratio of 2:1, and 3-methylpyridine (AP) and dimethylacetamide (DMAc) were diluted at a weight ratio of 1:1. 5.02 mL of AA diluent and 3.33 mL of AP diluent were then added to each solution. After thorough mixing, the solution was degassed using a centrifuge. The degassed solution was then poured onto a glass substrate and coated using a doctor blade with a 550 μm gap. The coated sample was baked in an 80°C oven for 20 minutes, then the temperature was increased to 170°C at a rate of 1.8°C / min and baked for another 20 minutes. Finally, the temperature was increased to 350°C at a rate of 2.0°C / min and baked for another 20 minutes. This was the final treatment.

[0150] A glass substrate was immersed in water, and a black matte polyimide film with a thickness of 18 μm was peeled off from the glass substrate.

[0151] The following table compares the examples with the comparative examples:

[0152] Table 1:

[0153]

[0154] As shown in Table 1, it can be confirmed that the black matte polyimide film manufactured according to the embodiments of the present invention not only exhibits excellent optical properties, but also has a lower peak height, making it less prone to bumps on the film surface and maintaining good mechanical properties.

[0155] Examples 3 to 6 show that the gloss performance of the black matte polyimide film can be controlled by adjusting the ratio between two polyimide matte agents with different median particle sizes. The closer the gloss values ​​of 60 degrees and 85 degrees are, the more consistent the appearance of the film material is when viewed from any angle.

[0156] Comparative Example 1 shows that when the median particle size of carbon black is too large, the bumps on the film surface increase, which in turn leads to a peak height greater than 300 nm.

[0157] Comparative Example 2 shows that when the proportion of the second polyimide matting agent is too high, it will cause an increase in bumps on the film surface. These bumps will cause defects in the film, resulting in a breakage elongation of less than 15%.

[0158] Comparative Example 3 shows that when the amount of polyimide matting agent added is too small, the gloss of the film will be greater than 30 GU.

[0159] Comparative Example 4 shows that when the median particle size of the polyimide matting agent is too small, it cannot produce a matting effect on the film surface.

[0160] Comparative Example 5 shows that when the median particle size of the polyimide matting agent or carbon black is too large, it will cause an increase in bumps on the film surface. These bumps will cause defects in the film, resulting in a breakage elongation of less than 15%.

[0161] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A black matte polyimide film, characterized in that, include: A polyimide, comprising 71-89 wt% of the polyimide film, wherein the polyimide is obtained by chemical cyclization after polymerization of diamine and dianhydride to form polyamic acid; Carbon black, comprising 2-9 wt% of the polyimide film, wherein the median particle size of the carbon black is less than 1 μm; and A polyimide matting agent, wherein the median particle size of the polyimide matting agent is 0.3-4 μm, and the polyimide matting agent accounts for 9-20 wt% of the weight of the polyimide film, such that the protrusion peak height of the polyimide film is less than 300 nm, the 60-degree gloss is less than 30 GU, and the transmittance is less than 1%.

2. The black matte polyimide film according to claim 1, characterized in that, The polyimide matting agent comprises a first polyimide matting agent and a second polyimide matting agent; The median particle size of the first polyimide matting agent is 1–4 μm, and it accounts for 5–20 wt% of the total weight of the polyimide matting agent. The median particle size of the second polyimide matting agent is 0.3-1 μm, and it accounts for 80-95 wt% of the total weight of the polyimide matting agent, so that the polyimide film has a gloss of 85 degrees less than 50 GU and a gloss of 60 degrees less than 30 GU.

3. The black matte polyimide film according to claim 1, characterized in that, The maximum particle size of the polyimide matting agent is less than 5 μm.

4. The black matte polyimide film according to claim 1, characterized in that, The polyimide film has a thickness of less than 30 μm and an elongation at break of more than 15%.

5. The black matte polyimide film according to claim 1, characterized in that, The membrane thickness is less than 30 μm.

Images