JP2014070170A - Black polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a black polyimide film having excellent light shielding property (low transmittance), low gloss property (low glossiness), insulating property (high dielectric breakdown voltage), and low water-absorbing property.SOLUTION: The black polyimide film includes: (a) 100 pts.wt. of a polyimide resin; (b) 1-20 pts.wt. of perylene black having a benzimidazole skeleton or low electroconductive carbon black; and (c) 3-30 pts.wt. of a filler. The polyimide resin (a) is produced by using a dehydrating agent and an imidation catalyst. The filler (c) has an average particle diameter of 1-10 μm, and a specific surface area of 1-100 m/g.

Description

  The present invention relates to a black polyimide film.

  2. Description of the Related Art In recent years, electronic devices have been rapidly improved in performance, function, and size, and accordingly, there is an increasing demand for downsizing and weight reduction of electronic components used in electronic devices. In response to the above request, the flexible printed wiring board is flexible and can withstand repeated bending, so it can be mounted three-dimensionally and densely in a narrow space, and functions as a wiring, cable, or connector for electronic devices. Its use as a given composite part is expanding. In recent years, in particular, it has been increasingly used in electronic and optical equipment such as cameras, video cameras, and optical pickups of CD-ROM drives, and accordingly, light shielding and low glossiness for flexible printed wiring boards have become important. ing. This light-shielding property is a characteristic required for flexible printed wiring boards used in the phobic parts of optical equipment, and is a characteristic that blocks the light that tries to enter the phobic parts from the outside with the wiring board. This is a characteristic of diffusing the reflected light so that the slight reflected light blocked by the light does not enter the aphobic portion again.

  In addition, the flexible printed wiring board is an electronic component that is indispensable for mobile phones and personal computers, and its demand is increasing year by year. In mobile phones and personal computers, design as well as function has become important, and there is a demand for flexible printed wiring boards that are black and have a low gloss (matte) texture.

  In order to impart light-shielding properties, conventionally, black ink was printed directly on the electrically insulating film on the coverlay film side of the flexible printed wiring board by a screen printing method or the like. However, in this method, screen printing is performed on a flexible printed wiring board having unevenness, so that workability is poor, and the printing process is increased during the circuit processing process, so that work efficiency is also deteriorated. In addition, when the circuit is processed and bent, the black ink is broken or peeled off to lose the light shielding property, or the inside of the device is contaminated by the black ink.

  In order to solve this problem, a black polyimide film having low gloss is disclosed.

  For example, it is disclosed that a light-shielding film can be obtained by applying and drying a solution on a mat-processed substrate and transferring the mat shape on the surface of the substrate to a film (for example, see Patent Document 1). . However, only one side of the film can be matted by this method, and the other side requires matting such as polishing.

  Furthermore, it is disclosed that a black heat-resistant light-shielding film can be obtained by matting the surface of a black film containing an inorganic filler (for example, see Patent Document 2). Since the matte feeling (low glossiness) of the film surface is insufficient only with the inorganic filler, matting treatment is additionally performed.

  Thus, in order to impart a mat feeling (low glossiness) to the film, a mat treatment by polishing or the like is required. Since the process is contaminated by the processing powder generated during the mat processing, a process for removing the processing powder is necessary, which is a complicated process.

  On the other hand, in order to impart a matte feeling to the film using only the inorganic filler, it is necessary to increase the amount of the inorganic filler added. Increasing the amount of the inorganic filler added not only makes the film brittle, but also increases the water absorption rate of the film.

Special table 2010-534342 gazette JP 2011-128598 A

  In order to obtain a black polyimide film having a low gloss on the film surface, it is necessary to add a matting treatment and / or a filler. In the mat treatment, the polishing powder may adhere to the film and contaminate the process. Moreover, the addition of the filler sometimes resulted in the film becoming brittle or increasing the water absorption rate of the film as the addition amount increased. This invention is made | formed in view of said subject, The objective is to provide the black polyimide film excellent in light-shielding property, low glossiness, insulation, and low water absorption.

As a result of intensive studies to solve such problems, the present inventors have found that (a) 100 parts by weight of a polyimide resin and (b) 1 to 20 parts by weight of perylene black having a benzimidazole skeleton or low-conductivity carbon black. And (c) 3-30 parts by weight of filler, (a) the polyimide resin is produced using a dehydrating agent and an imidization catalyst, and (c) the filler has an average particle size of 1-10 μm, In addition, by using a black polyimide film characterized by having a specific surface area of 1 to 100 m ² / g, the matte treatment of the obtained film is unnecessary, and excellent light-shielding properties (low transmittance) and low glossiness ( The inventors have found that a black polyimide film having low gloss), insulating properties (high dielectric breakdown voltage), and low water absorption can be obtained, and the present invention has been completed.

That is, the present invention includes (a) 100 parts by weight of polyimide resin, (b) 1 to 20 parts by weight of perylene black or low conductive carbon black having a benzimidazole skeleton, and (c) 3 to 30 parts by weight of filler. The (a) polyimide resin is manufactured using a dehydrating agent and an imidization catalyst, and the (c) filler has an average particle size of 1 to 10 μm and a specific surface area of 1 to 100 m ² / g. This is a black polyimide film.

  The (b) is preferably perylene black having a benzimidazole skeleton.

  The perylene black having the benzimidazole skeleton preferably has a heat loss rate of less than 3% after 350 ° C. for 20 minutes.

  The (c) filler is preferably silicon oxide.

  The glossiness of the film surface is preferably 1 to 50%.

  The black polyimide film according to the present invention has excellent light shielding properties, low glossiness, insulating properties, and low water absorption, and is excellent in design. It can be used for coverlay films and coverlays on flexible printed circuit boards.

  Embodiments of the present invention will be described below.

  A black polyimide film is a polyimide film having a total light transmittance of less than 0.6%. Although the polyimide film is mainly colored with pigment, the pigment itself does not need to be black, and the total light transmittance of the film can be less than 0.6% in the film state that combines the polyimide film, pigment, and filler. It ’s fine.

  The pigment is perylene black having a benzimidazole skeleton or low-conductivity carbon black. Among them, it is more preferable to use perylene black having a benzimidazole skeleton in terms of coloring power and insulating properties. Among the perylene blacks having a benzimidazole skeleton, the weight loss ratio after heating at 350 ° C. for 20 minutes is less than 3%. Perylene black having a certain benzimidazole skeleton is particularly preferred because it can prevent contamination in the process of producing a black polyimide film.

  Content of a pigment is 1-20 weight part with respect to 100 weight part of polyimide resins, and 1-10 weight part is preferable in terms of cost. If it is less than 1 part by weight, the film does not become black, and if it exceeds 20 parts by weight, the film may become brittle or the insulation may be lowered.

  The material of the filler is not particularly limited as long as the black polyimide film can exhibit low gloss, mechanical properties and insulation, and low water absorption, but preferred fillers include aluminum oxide, titanium oxide, zinc oxide, magnesium oxide, Examples include silicon oxide, calcium phosphate, barium sulfate, and aluminum hydroxide. Among these, silicon oxide is preferable because it does not affect the color of the film and has little influence on the solution used when preparing the flexible printed circuit board. Examples of silicon oxide include fused silica, porous silica, silica gel, fumed silica, and spherical silica from the viewpoints of shape, production method, and the like. The silicon oxide is not particularly limited as long as it satisfies the characteristics of the filler to be described later, but in terms of reducing the water absorption of the film, the fused silica or the surface —OH group is heated or capped with a substituent. The surface-treated porous silica is preferably used, and fused silica that can be used without treatment is more preferable. By reducing the water absorption rate of the film, insulation is improved.

  The content of the filler is 3 to 30 parts by weight with respect to 100 parts by weight of the polyimide resin, and 12 to 30 parts by weight is in terms of reducing the glossiness in a wide range of filler particle sizes. preferable. When the content is less than 3 parts by weight, the gloss cannot be lowered, and when it exceeds 30 parts by weight, the mechanical strength of the film is lowered and the film cannot be obtained.

  The filler has an average particle diameter of 1 to 10 μm. If the average particle size is 1 μm or less, the glossiness cannot be lowered, and if it is 10 μm or more, the mechanical strength of the film is greatly reduced. When the average particle diameter is 1 to 8 μm, it is preferable in that low gloss can be realized with a smaller amount.

The specific surface area of the ^filler, if 1m ² / g~100m 2 / g, it is possible to combine the low glossiness, insulation and low water absorption of the film. When the specific surface area of the filler is less than 1 m ² / g, the solvent affinity on the filler surface is low and it is difficult to disperse. When it is larger than 100 m ² / g, the water absorption rate of the black polyimide film tends to increase in the filler addition amount that can realize the low glossiness of the black polyimide film. In terms of reducing the water absorption of the black polyimide film ^{1m 2} / ^g~50m 2 / g are preferred.

The polyimide resin contained in the black polyimide film is produced using a dehydrating agent and an imidization catalyst. Since a black polyimide film contains a pigment and a filler, it becomes brittle. In particular, if the specific surface area of the filler used filler 1m 2 ^/ g~100m 2 ^{/ g,} whereas that can lower the water absorption of black polyimide film, in order to realize low gloss of the film contains a large amount of filler It is necessary to let The polyimide resin contained in the black polyimide film is manufactured using a dehydrating agent and an imidization catalyst, thereby improving the mechanical properties of the film. Furthermore, since the polyimide resin is produced using a dehydrating agent and an imidization catalyst, it is possible to reduce the filler content necessary to realize the low glossiness of the film. For this reason, it is important that the polyimide resin constituting the black polyimide film is manufactured using a dehydrating agent and an imidization catalyst.

  Next, the polyimide film according to the present invention will be described.

  The black polyimide film preferably has a thickness of 5 to 75 μm. The thickness of the film depends on the application. For example, when used for a cover lay film of a flexible printed wiring board, the thickness of the polyimide film is preferably 5 to 25 μm. When used for a base film (substrate) of the flexible printed wiring board, the thickness of the polyimide film is 5-75 micrometers is preferable.

  The surface roughness of the black polyimide film is preferably 10-point average roughness (Rz) of 1.0 to 4.0 μm. If Rz is less than 1.0 μm, low gloss may not be obtained, and if it exceeds 4.0 μm, it tends to be difficult to uniformly laminate the adhesive on the black polyimide film. This surface roughness (Rz) can be adjusted by the average particle diameter of the filler, the filler content and the imidization method. When the average particle size of the filler is large, Rz increases, and when the filler content is large, Rz increases. In the imidization method, Rz tends to be larger in the chemical imidization method than in the thermal imidization method.

  A polyimide film is obtained from the polyamic acid solution which is the precursor. This polyamic acid solution can be produced by a method commonly used by those skilled in the art. That is, one or two or more tetracarboxylic dianhydride components and one or two or more diamine components are used in substantially equimolar amounts and polymerized in an organic polar solvent to obtain a polyamic acid solution.

  Typical acid dianhydride components used in the production of polyimide films include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4, 4'-diphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,4'-oxydiphthalate Acid anhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4'-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 4,4'-hexafluoroisopropylidene Dendiphthalic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, p-phenylenebis (trimethyl Aromatic tetracarboxylic dianhydrides such as litter acid monoester anhydride) and p-phenylenediphthalic anhydride. Among these, pyromellitic dianhydride is preferable in terms of heat resistance.

  Examples of the diamine component include 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 2,2-bis (4-aminophenoxyphenyl) propane, 1,4-bis (4-aminophenoxy) benzene, 1 , 3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (3-aminophenoxy) phenyl ) Sulfone, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis (4-aminophenoxyphenyl) hexafluoropropane, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenylsulfone 9,9-bis (4-aminophenyl) fluorene, bisaminophenoxy Ketone, 4,4 '-(1,4-phenylenebis (1-methylethylidene)) bisaniline, 4,4'-(1,3-phenylenebis (1-methylethylidene)) bisaniline, metaphenylenediamine, paraphenylene Aromatic diamines such as diamine, 4,4'-diaminobenzanilide, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, or other fats Group diamines can be mentioned. Among these, paraphenylenediamine is preferable in terms of heat resistance and low heat shrinkage.

  As for the polyimide film of this invention, it is desirable that the weight average molecular weights of the polyamic acid which is the precursor are 10,000-1,000,000. If the weight average molecular weight is less than 10,000, the resulting film may become brittle. On the other hand, if the weight average molecular weight exceeds 1,000,000, the viscosity of the polyamic acid solution, which is a polyimide precursor, becomes too high and handling may be difficult.

  Examples of the organic polar solvent used in the polyamic acid production reaction include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide; N, N -Acetamide solvents such as dimethylacetamide and N, N-diethylacetamide; pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone; phenol, o-, m-, or p-cresol, Examples thereof include phenol solvents such as xylenol, halogenated phenol, and catechol; or hexamethylphosphoramide and γ-butyrolactone. These are preferably used alone or as a mixture. Furthermore, aromatic hydrocarbons such as xylene and toluene may be partially mixed in the solvent. Further, it is desirable from the viewpoint of handling that this polyamic acid polymer is dissolved in the organic polar solvent in an amount of 5 to 40% by weight, preferably 10 to 30% by weight.

  The method for adding the pigment and / or filler to the polyimide film in the present invention is a method in which the above polyamic acid is added in advance to the solvent before polymerization, and during the polymerization of the polyamic acid, the pigment and / or filler, or the A method of adding the dispersion liquid to the polyamic acid solution, a method of dispersing the pigment and / or filler in a solvent in advance, and adding the dispersion liquid to the polyamic acid solution can be mentioned, but there is no particular limitation. When adding the pigment and / or filler and the dispersion thereof to the solvent before or during the polymerization of the polyamic acid, it is preferable to control the moisture content of the pigment and / or filler to be low. Since the filler having a small specific surface area hardly adsorbs moisture on the surface, it is easy to control the moisture, and therefore the filler can be added before or during the polymerization of the polyamic acid. The moisture content of pigments and / or fillers is managed by managing the moisture contained in the solid state (packaging that does not absorb water, drying before dispersion, etc.), and managing the moisture contained in the dispersion state. It is preferable to strictly control by a method (such as mixing a dehydrating agent in the dispersion). In addition, when adding a dispersion of pigment and / or filler to the polymyad acid solution, there is a risk of poor mixing due to a difference in viscosity between the two solutions, and shock aggregation of the pigment and / or filler. It is preferable to lower the solid component concentration of the dispersion liquid of the filler. When using a dispersion of pigment and / or filler, a polyamic acid solution is added to the dispersion to increase the solution viscosity, or a fine filler is added to increase the thixotropy of the dispersion. It is preferable to improve the stability.

  As a method for dispersing the pigment and / or filler, a known dispersion technique such as a ball mill, a bead mill, a three-roll, a homogenizer, an ultrasonic wave, stirring using a stirring blade, or the like can be applied. The pigment and the filler may be prepared separately, or may be a single dispersion.

  As a method for producing a black polyimide film, there are a thermal imidization method and a chemical imidization method. The thermal imidization method is a method in which imidization is performed only with heat without using a dehydrating agent, and an imidization catalyst can be used in combination. The chemical imidization method is a method of imidization using a dehydrating agent, and it is essential to use an imidization catalyst in combination. The imidization of the polyamic acid is a competitive reaction between the imidization reaction and the amide bond opening reaction of the polyamic acid, and it is preferable to employ a chemical imidization method having a high imidization reaction rate. In particular, since the polyimide film as in the present invention becomes brittle when it contains a pigment and a filler, the production of a black polyimide film by a chemical imidization method is a mechanical property such as elongation rate and tensile strength of the polyimide film. As a result, the chemical imidization method is excellent in the film-forming property of the polyimide film. In addition, since the chemical imidization method uses a dehydrating agent and an imidization catalyst, the imidization reaction proceeds at a relatively low temperature compared to the thermal imidization method. For this reason, it is difficult to embed the filler in the film during the process of modifying the polyamic acid solution described later into a polyimide film, and low gloss can be achieved even if the filler content is small. And more preferable.

  Examples of the imidization catalyst used in the thermal imidization method or the chemical imidization method include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, pyridine, picoline, isoquinoline and the like. Heterocyclic tertiary amines are preferable, and it is preferable to use heterocyclic tertiary amines from the viewpoint of improving the mechanical properties of the film. The addition amount of the imidization catalyst is preferably 0.3 to 1.5 equivalents relative to the number of amide bonds of the polyamic acid.

  Examples of the dehydrating agent used in the chemical imidization method include aliphatic acid anhydrides such as acetic anhydride and aromatic acid anhydrides such as benzoic anhydride. The reaction product is heated from the film by heating. Acetic anhydride is preferably used because it is easy to remove. The addition amount of the dehydrating agent is preferably 1.3 to 3.0 equivalents relative to the number of amide bonds of the polyamic acid.

  The dope solution in which the pigment, filler and polyamic acid solution and the imidization catalyst and dehydrating agent, or the imidization catalyst are mixed, is cooled to −10 to 10 ° C. It is preferably cast on an endless belt and dried with hot air at 200 ° C. or lower for 10 to 1000 seconds. Thereafter, the self-supporting gel film is peeled off from the drum or the endless belt, both ends of the film are fixed with metal pins or metal clips, and fired in a hot air oven at 150 ° C. or higher and 500 ° C. or lower for 3 to 600 seconds. Then, it is preferable to carry out additional firing for 3 to 600 seconds in an IR furnace at 400 ° C. or higher and 600 ° C. or lower, and finally for 3 to 600 seconds in a hot air oven at 400 ° C. or lower.

  After that, since both ends of the film fixed with metal pins or metal clips remain fixed, it is preferable that both ends of the film are cut off and wound up as a film roll in order to prevent wrinkling of the film roll.

  The black polyimide film is a method of applying various organic substances such as thermosetting resin, thermoplastic resin, organic monomer, coupling agent, etc. as a primer for the purpose of improving adhesion to different materials such as adhesives, metal hydroxide, Various surface treatments such as a surface treatment method with a product, organic alkali, etc., a plasma treatment method, a corona treatment method, a surface grafting method and the like can be carried out alone or in combination.

  As for the total light transmittance of the black polyimide film, the total light transmittance at the thickness of the obtained film is preferably less than 0.6%. If it is 0.6% or more, light is transmitted and the shielding property is lowered.

  The glossiness of the black polyimide film is preferably 1 to 50% in that the appearance of the film surface can be made uniform. If it exceeds 50%, it is insufficient to scatter light incident on the film surface, and the appearance of the film surface varies depending on the incident angle of light. The glossiness of the black polyimide film is preferably 1 to 50%, even if the incident light on the film surface is strong, it is preferable in terms of scattering the incident light and becoming a homogeneous film surface, more preferably 1 to 30%, 1 to 20% is particularly preferable.

  The insulation property of the black polyimide film is evaluated by a dielectric breakdown voltage. The dielectric breakdown voltage in the normal state of the black polyimide film is preferably 100 V / μm or more, and more preferably 150 V / μm or more. If it is less than 100 V / μm, insulation failure will occur when used for flexible printed wiring boards when high voltage is used. In addition, the dielectric breakdown voltage at the time of water absorption may cause faulty insulation due to leakage in the contact portion between the flexible printed wiring board and other components, rather than the portion covered with the black polyimide film in the flexible printed wiring board. Most of them are preferably 10 V / μm or more, more preferably 80 V / μm or more.

  The water absorption rate of the black polyimide film is preferably less than 3%. When the water absorption rate of the film is 3% or more, when the flexible printed circuit board is processed, there is a case where the chemical solution is difficult to come off from the black polyimide film, and a long processing time is required for the flexible printed circuit board.

  The appearance of the black polyimide film is preferably free from aggregates of pigments and / or fillers.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to these. In addition, the characteristic of the used filler and the obtained film in an Example and a comparative example was evaluated as follows.

[Average particle size]
The average particle size was calculated using a laser diffraction particle size distribution analyzer SALD-3100 manufactured by Shimadzu Corporation, and the average particle size was determined.

〔Specific surface area〕
The specific surface area was measured using Tristar II 3020 (BET method) manufactured by Shimadzu Corporation, and the value was defined as the specific surface area.

[Total light transmittance]
The total light transmittance (%) was defined as the total light transmittance according to ASTM D 1003 using a Nippon Denshoku Industries Co., Ltd. haze meter, NDH 5000. A total light transmittance of less than 0.6% was designated as “◯”, and 0.6% or more was designated as “x”.

[Glossiness]
A value obtained by measuring glossiness (%) at an incident angle of 60 ° using a gloss meter V-7000 manufactured by Nippon Denshoku Industries Co., Ltd. was defined as glossiness. A glossiness of less than 50% was designated as “◯”, and 50% or more as “x”.

[Dielectric breakdown voltage]
A value V / μm obtained by dividing the value of the dielectric breakdown voltage measured by the thickness of the measurement sample as the dielectric breakdown voltage was measured according to JIS C 2110-7.1. Dielectric breakdown voltage is implemented at two levels, normal and after water absorption. The measurement in a normal state was performed after leaving for 48 hours in an environment of 23 ° C. (± 3 ° C.) / 55% RH (± 5% RH). In the measurement after water absorption, distilled water was put into a vat and immersed for 48 hours so that the film did not float on distilled water. Then, after taking out a film, the water drop on the film surface was wiped off, and it measured within 3 minutes after taking out a film. The dielectric breakdown voltage in a normal state was “◯” when 150 V / μm or more, “Δ” when 100 V / μm or more and less than 150 V / μm, and “X” when less than 100 V / μm.
In addition, the dielectric breakdown voltage after water absorption was evaluated as “◯” when 80 V / μm or more and “Δ” when less than 80 V / μm.

[Water absorption rate]
After drying at 150 ° C. for 30 hours, it was placed in a desiccator and allowed to stand for 30 minutes, and the film weight was measured. Thereafter, the film was immersed in a vat containing distilled water and allowed to stand for 24 hours. Then, the film was taken out, water drops on the film surface were wiped off, and the film weight was measured within 3 minutes after taking out the film. Less than 3% was “◯”, and 3% or more was “x”.

〔appearance〕
After film formation, it was judged by visual observation whether filler aggregates were generated on the film. A case where no aggregate was generated was designated as “no”, and a case where aggregate was produced was designated as “present”.

[Film-forming properties]
During the film forming operation, the film that was torn because it was brittle was marked with “×”, and the film that was obtained without tearing was marked with “◯”.

(Synthesis Example 1: Synthesis of polyamic acid solution A)
80,9 g of N, N-dimethylformamide (DMF) cooled to 10 ° C., 10.1 g of p-phenylenediamine (p-PDA), and 56 of 4,4′-diaminodiphenyl ether (4,4′-ODA) After 2 g was added and dissolved, 79.2 g of pyromellitic dianhydride (PMDA) was added and stirred for 60 minutes to dissolve. Furthermore, a DMF solution of PMDA (PMD 2.45 g / DMF 31.6 g) separately prepared was carefully added to this solution, and the addition was stopped when the viscosity reached about 3000 poise. Stirring was performed for 1 hour to obtain a polyamic acid solution A having a solid concentration of about 15% by weight and a rotational viscosity at 23 ° C. of 3200 poise.

(Formulation Example 1: Preparation of pigment dispersion)
30 g of pigment was mixed with 470 g of DMF and then dispersed using a bead mill to obtain a pigment dispersion having a solid component concentration of 6%. It was confirmed that the dispersed state did not contain coarse particles of 1 μm or more with a grind gauge.

(Formulation example 2: Preparation of filler dispersion)
50 g of filler was mixed with 450 g of DMF and then dispersed with a homogenizer to obtain a filler dispersion having a solid component concentration of 10%.

(Synthesis Example 2: Synthesis of polyamic acid solution B)
80,9 kg of N, N-dimethylformamide (DMF) cooled to 10 ° C., 10.1 kg of p-phenylenediamine (p-PDA), and 56 of 4,4′-diaminodiphenyl ether (4,4′-ODA) After 2 kg was added and dissolved, 79.2 kg of pyromellitic dianhydride (PMDA) was added and stirred for 60 minutes to dissolve. Further, a DMF solution of PMDA (PMDA 2.45 kg / DMF 31.6 kg) prepared separately was added carefully to this solution, and the addition was stopped when the viscosity reached about 3000 poise. Stirring was performed for 1 hour to obtain a polyamic acid solution B having a solid content concentration of about 15% by weight and a rotational viscosity at 23 ° C. of 3200 poise.

(Formulation example 3: Preparation of pigment filler dispersion)
30 kg of pigment was mixed with 470 kg of DMF, and then dispersed using a bead mill to obtain a pigment dispersion having a solid component concentration of 6%. The dispersion state was confirmed by a grind gauge to contain no coarse particles of 1 μm or more, and used for the experiment. Further, 48 kg of filler was mixed with 432 kg of DMF, and then dispersed with a homogenizer to obtain a filler dispersion having a solid component concentration of 10%. 500 kg of the obtained pigment dispersion and 480 kg of the filler dispersion were mixed to obtain a pigment filler dispersion.

(Formulation Example 4: Preparation of imidizing agent)
175.6 kg of DMF was mixed with 56.8 kg of isochelin and 127.6 kg of acetic anhydride to prepare an imidizing agent.

Example 1
15.4 g of a pigment dispersion prepared in the same manner as in Preparation Example 1 using perylene black having a benzimidazole skeleton as a pigment (Lumogen Black FK4280 manufactured by BASF: heat loss ratio after 350 ° C. × 20 minutes is 6%) And using silicon oxide (FB-5SDC manufactured by Denki Kagaku Kogyo Co., Ltd .: average particle size 4.5 μm, specific surface area 3 m ² / g) as filler, 5.5 g of filler dispersion prepared in the same manner as in Preparation Example 2 was mixed. Then, a pigment filler dispersion was prepared. Thereafter, 135.6 g of the polyamic acid solution A obtained in Synthesis Example 1 and the pigment filler dispersion were mixed to prepare a dope, and cooled at a temperature of 0 ° C. or lower. To the dope, an imidizing agent (acetic anhydride / isoquinoline / DMF = 19.1 g / 8.5 g / 26.0 g) was added, stirred and degassed at a temperature of 0 ° C. or lower, and on a aluminum foil using a comma coater. It was cast and applied. This resin film is heated at 120 ° C. for 60 seconds, and then the self-supporting gel film is peeled off from the aluminum foil and fixed to the metal frame. Drying and imidization gave a 12 μm thick black polyimide film. The obtained polyimide film contains 5 parts by weight of pigment and 3 parts by weight of filler with respect to 100 parts by weight of polyimide resin. The properties of the obtained film are shown in Table 1.

(Examples 2 and 3)
A black polyimide film was obtained in the same manner as in Example 1 except that the addition amount of the filler was changed. The properties of the obtained film are shown in Table 1.

Example 4
The type of pigment was changed to carbon black (Special Black 4 manufactured by Evonik Degussa), and the amount added to the film was 5 parts by weight with respect to 100 parts by weight of the polyimide resin. Moreover, the addition amount of the filler was changed and the black polyimide film was obtained like Example 1. FIG. The properties of the obtained film are shown in Table 1.

(Example 5)
A black polyimide film was obtained in the same manner as in Example 4 except that the addition amount of the filler was changed. The properties of the obtained film are shown in Table 1.

(Example 6)
The type of filler was changed to silicon oxide (FB-3SDC manufactured by Denki Kagaku Kogyo Co., Ltd .: average particle size 3.4 μm, specific surface area 3 m ² / g), and the amount added to the film was 8 wt. A black polyimide film was obtained in the same manner as in Example 1. The properties of the obtained film are shown in Table 1.

(Example 7)
A black polyimide film was prepared in the same manner as in Example 6 except that the type of pigment was changed to perylene black having a benzimidazole skeleton (Lumogen Black FK4281 manufactured by BASF: 1% of heat loss after 350 ° C. × 20 minutes). Obtained. The properties of the obtained film are shown in Table 1.

(Example 8)
A black polyimide film was obtained in the same manner as in Example 6 except that the type of the pigment was changed to carbon black (Special Black 4 manufactured by Evonik Degussa). The properties of the obtained film are shown in Table 1.

Example 9
A black polyimide film was obtained in the same manner as in Example 6 except that the addition amount of the filler was changed. The properties of the obtained film are shown in Table 2.

(Example 10)
The filler type was changed to silicon oxide (FB-7SDC manufactured by Denki Kagaku Kogyo Co., Ltd .: average particle size 5.8 μm, specific surface area 2 m ² / g), and the amount added to the film was 8 wt. Except having changed into the part, it carried out similarly to Example 1, and obtained the black polyimide film. The properties of the obtained film are shown in Table 2.

(Example 11)
The filler type was changed to silicon oxide (HS-303 manufactured by Micron Corporation: average particle size 9.5 μm, specific surface area 1 m ² / g), and the amount added to the film was 12 parts by weight with respect to 100 parts by weight of the polyimide resin. Except having changed, it carried out similarly to Example 1, and obtained the polyimide film. The properties of the obtained film are shown in Table 2.

(Example 12)
The filler type was changed to silicon oxide (HS-301 manufactured by Micron: average particle size 2.4 μm, specific surface area 8 m ² / g), and the amount added to the film was 12 parts by weight with respect to 100 parts by weight of the polyimide resin. Except having changed, it carried out similarly to Example 1, and obtained the polyimide film. The properties of the obtained film are shown in Table 2.

(Examples 13 to 15)
A black polyimide film was obtained in the same manner as in Example 1 except that the addition amount of the pigment and the thickness of the film were changed. The properties of the obtained film are shown in Table 2.

(Example 16)
Perylene black having a benzimidazole skeleton as a pigment (Lumogen Black FK4280 manufactured by BASF: heating loss ratio after 350 ° C. × 20 minutes is 6%), and silicon oxide (FB-3SDC manufactured by Denki Kagaku Kogyo Co., Ltd .: average) as a filler A pigment filler dispersion was prepared in the same manner as in Preparation Example 3 using a particle size of 3.4 μm and a specific surface area of 3 m ² / g). Immediately after mixing with a mixer, the amount of the polyamic acid solution B synthesized in Synthesis Example 2 was 27.5 kg / h, the amount of the imidizing agent prepared in Preparation Example 4 was 12.5 kg / h, and the pigment was mixed. The discharge amount of the filler dispersion was adjusted to 6.1 kg / h, and then mixed with a mixer to obtain a dope. The obtained dope is cast from a single-layer die to an endless belt, heated at 120 ° C. for 60 seconds, and then the self-supporting gel film is peeled off from the endless belt, and both ends of the gel film are fixed with metal pins. did. Since the gel film contains a large amount of pigments and fillers, the gel film is brittle compared to the gel film that does not contain the gel film. Therefore, a plurality of rows of metal pins are arranged, and the gel films are fixed with a plurality of rows of metal pins. Then, the gel film was put into a tenter furnace, dried and imidized at 250 ° C. for 11 seconds, 350 ° C. for 11 seconds, and 450 ° C. for 120 seconds to obtain 10,000 m of a polyimide film having a thickness of 12 μm and a film width of 500 mm. The speeds of the endless belt and the tenter furnace were adjusted so that the thickness of the obtained film was 12 μm with respect to the discharge amount. The obtained polyimide film contains 5 parts by weight of pigment and 8 parts by weight of filler with respect to 100 parts by weight of polyimide resin. The properties of the obtained film were the same as in Example 6. Further, when the heating furnace was confirmed, it was found that the components contained in the pigment were sublimated and recrystallized to make the inside of the furnace dirty without causing a difference in film characteristics. The dirt in the furnace was analyzed by IR, and it was confirmed that the dirt was a component contained in the pigment.

(Example 17)
A polyimide film was obtained in the same manner as in Example 16 except that the type of pigment was changed to perylene black having a benzimidazole skeleton (Lumogen Black FK4281 manufactured by BASF: 350 ° C. × 1 minute loss on heating after 20 minutes). It was. The properties of the obtained film were the same as in Example 7. Moreover, when the heating furnace was confirmed, the inside of the furnace was not dirty with the components contained in the pigment.

(Comparative Example 1)
A polyimide film was obtained in the same manner as in Example 1 except that the addition amount of the filler was changed. Table 3 shows the composition of the polyimide film and the characteristics of the obtained film.

(Comparative Example 2)
The filler type was changed to silicon oxide (Silicia 350 manufactured by Fuji Silysia Co., Ltd .: average particle size 3.9 μm, specific surface area 300 m ² / g), and the amount added to the film was 4 parts by weight with respect to 100 parts by weight of the polyimide resin. A polyimide film was obtained in the same manner as in Example 1 except for the change. The properties of the obtained film are shown in Table 3.

(Comparative Example 3)
The filler type was changed to silicon oxide (Silicia 550 manufactured by Fuji Silysia Co., Ltd .: average particle size 3.9 μm, specific surface area 500 m ² / g), and the amount added to the film was 8 parts by weight with respect to 100 parts by weight of the polyimide resin. A polyimide film was obtained in the same manner as in Example 1 except for the change. Table 3 shows the composition of the polyimide film and the characteristics of the obtained film.

(Comparative Example 4)
The pigment was changed to carbon black (Special Black 4 manufactured by Evonik Degussa), and the type of filler was changed to silicon oxide (Silicia 350 manufactured by Fuji Silysia Co., Ltd .: average particle size 3.9 μm, specific surface area 300 m ² / g). A polyimide film was obtained in the same manner as in Example 1 except that the amount added was changed to 8 parts by weight with respect to 100 parts by weight of the polyimide resin. The properties of the obtained film are shown in Table 3.

(Comparative Example 5)
The type of filler was changed to silicon oxide (FB-3SDC manufactured by Denki Kagaku Kogyo Co., Ltd .: average particle size 3.4 μm, specific surface area 3 m ² / g), and the amount added to the film was 40 wt. A polyimide film was produced in the same manner as in Example 1 except that the film was changed to a part. However, since the film was brittle, a uniform film could not be obtained. The characteristics are shown in Table 3.

(Comparative Example 6)
A polyimide film was produced in the same manner as in Example 2 except that no imidization catalyst and dehydrating agent were used. However, since the film was brittle, a uniform film could not be obtained. The characteristics are shown in Table 3.

(Comparative Example 7)
A polyimide film was produced in the same manner as in Example 6 except that an imidization catalyst and a dehydrating agent were not used. However, since the film was brittle, a uniform film could not be obtained. The characteristics are shown in Table 3.

(Comparative Example 8)
A polyimide film was produced in the same manner as in Example 1 except that an imidization catalyst and a dehydrating agent were not used. However, since the film was brittle, a uniform film could not be obtained. The characteristics are shown in Table 3.

(Comparative Example 9)
The type of filler was changed to silicon oxide (Snowtex-ZL manufactured by Nissan Chemical Co., Ltd .: average particle size 0.1 μm, specific surface area 30 m ² / g), and the content in the film was 15 weights with respect to 100 parts by weight of the polyimide resin. A polyimide film was obtained in the same manner as in Example 1 except that the part was used. Table 4 shows the properties of the obtained film.

(Comparative Example 10)
The filler type was changed to silicon oxide (Silicia 470 manufactured by Fuji Silysia Ltd .: average particle size 14.1 μm, specific surface area 350 m ² / g), and the content in the film was 15 parts by weight with respect to 100 parts by weight of the polyimide resin. A polyimide film was produced in the same manner as in Example 1 except that the film was brittle, and a uniform film could not be obtained. The characteristics are shown in Table 4.

Claims (5)

(A) 100 parts by weight of polyimide resin,
(B) 1-20 parts by weight of perylene black or low conductive carbon black having a benzimidazole skeleton, and (c) 3-30 parts by weight of filler,
The (a) polyimide resin is manufactured using a dehydrating agent and an imidization catalyst, and the (c) filler has an average particle diameter of 1 to 10 μm and a specific surface area of 1 to 100 m ² / g. A black polyimide film.   The black polyimide film according to claim 1, wherein (b) is perylene black having a benzimidazole skeleton.   The black polyimide film according to claim 1 or 2, wherein the perylene black having a benzimidazole skeleton has a heating loss rate of less than 3% after 20 minutes at 350 ° C.   The black polyimide film according to claim 1, wherein the filler (c) is silicon oxide.   The glossiness of a film surface is 1 to 50%, The black polyimide film as described in any one of Claims 1-4 characterized by the above-mentioned.