JP3940119B2 - Polyimide precursor liquid composition and polyimide coating - Google Patents

Description

  The present invention relates to polyimide precursors and polyimide coatings (including films, sheets and tubular bodies) that are essentially colorless and transparent. More particularly, the present invention relates to an essentially colorless and transparent polyimide coating useful for optical fibers, liquid crystal display substrates, electroluminescent substrates, protective sheets, and the like, and essentially colorless and transparent useful for heat resistant coatings. Related to polyimide films and the like.

  Polyimide coatings and films require thermal stability and good electrical and mechanical properties and are used in many different product applications that are considered desirable. In addition, polyimide coatings and films having good transparency have been widely used as films in liquid crystal display devices, electroluminescent substrates, optical fiber cable coatings, waveguides, protective coatings for solar cells, and the like. Such polyimide coatings and films have good transparency but are often colored yellow or brown as a result of the severe thermal history leading to film formation. This coloring has a problem in applications such as a film for liquid crystal, in which coloring darkens the field of view and impairs the function of the liquid crystal display device.

  In response to the problems described above, various polyimide coatings and films have been developed that exhibit low color and high transparency. The development of such prior art coatings and films has been guided by a series of studies focused on the cause of coloration of transparent polyimide films. These studies report that polyimide coloration is highly dependent on the type of aromatic tetracarboxylic dianhydride and diamino compound selected for use as the starting material for the polyimide. In particular, these studies show that aromatic diamines having an amino group at the meta position are particularly effective as diamino compounds, and that a mixture of this and biphenyltetracarboxylic dianhydride can lead to the formation of colorless and transparent polyimides. (Patent Document 1 below). The development of such prior art coatings and films has been guided by the well-known principle that higher production or polymerization temperatures adversely affect the degree of coloration of the resulting polyimide. The aromatic tetracarboxylic dianhydride and diamino compound are polymerized at a temperature of 80 ° C. or lower to form a polyamic acid solution, and then the polyamic acid is actually imidized by thermal or chemical means. Prior art polyamic acids are produced.

However, in the said patent document 1, since it superposes | polymerizes at the temperature of 80 degrees C or less, there existed a problem that a superposition | polymerization rate was low and production cost was high. In order to solve this problem, Dietz proposes a polyimide with low production cost according to Patent Document 2 below.
U.S. Pat.No. 4,876,330, column 1, line 64, line 2 to line 6, column 8, lines 25-39 JP 2000-313804 A

  However, in recent electronic devices such as liquid crystal elements, image devices such as electroluminescence (EL), optical fibers, optical waveguides, protective coatings for solar cells, and printed boards, polyimides with higher transparency are required.

  The present invention provides a polyimide coating with improved transparency and higher transparency, and a polyimide precursor solution used therefor.

In order to achieve the above object, a polyimide precursor liquid composition of the present invention comprises a polyimide precursor comprising at least one tetracarboxylic dianhydride or derivative thereof, at least one diamine or derivative thereof, and a polar polymerization solvent. A body fluid composition comprising:
Furthermore, it includes a cyclic structure compound having a 5-membered ring structure containing a carbonyl group (C═O bond) different from the polar polymerization solvent, and the cyclic structure compound has a boiling point of 200 ° C. or higher, and includes carbon, hydrogen and At least one cyclic structure compound selected from ethylene carbonate, propylene carbonate, butylene carbonate and γ-butyrolactone , which is composed of oxygen atoms and does not contain nitrogen, phosphorus, and sulfur heteroatoms;
The tetracarboxylic dianhydride is a compound represented by the compound represented by the following formula (A) and formula (B),
The diamine is a compound represented by the following chemical formula (I) .

  The polyimide coating of the present invention is characterized in that the polyimide precursor liquid composition is imide-converted.

  The present invention comprises at least one tetracarboxylic dianhydride or derivative thereof, at least one diamine or derivative thereof, a polar polymerization solvent, a boiling point of 200 ° C. or higher, and carbon, hydrogen and oxygen atoms. By using a polyimide precursor liquid composition containing a cyclic structure compound constituted by the following, it is possible to provide a polyimide film having further increased transparency as compared with the prior art.

A preferable raw material composition that can be used in the present invention is an aromatic tetracarboxylic dianhydride composed of the compound represented by the chemical formula (A) and the compound represented by the chemical formula (B), and the chemical formula (I). An aromatic diamine,
A polar polymerization solvent;
Including a cyclic structure compound, the cyclic structure compound is a cyclic structure compound having a boiling point of 200 ° C. or higher and composed of carbon, hydrogen, and oxygen atoms.

  Polar organic solvents generally used for polymerization of polyamic acid, which is a polyimide precursor, are N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone (NMP), Dimethyl sulfoxide (DMSO) or the like forms a strong solvation or complex with the polyamic acid which is a polyimide precursor, adheres to the polyamic acid, and may be thermally decomposed during baking at 300 ° C. or higher. When these solvents are thermally decomposed, they contain nitrogen (N), sulfur (S) atoms, and the like, which causes coloring.

The present inventors added a compound having no hetero atom such as nitrogen, phosphorus and sulfur and having a boiling point higher than that of a polar organic solvent as a polymerization solvent, and a polar organic solvent as a polymerization solvent having a low boiling point. As a result of diligent research on the hypothesis that coloration at the time of high-temperature firing could be prevented, and using a compound that does not contain heteroatoms such as nitrogen, phosphorus, and sulfur, and that has a high boiling point and a cyclic structure, It has been found that it is effective in preventing coloring. In particular, a compound having a five-membered ring structure containing a carbonyl group (C═O bond) generally has a dipole moment and a dielectric constant larger than those of polar organic solvents used for polyamic acid polymerization, and is derived from a five-membered ring. It has been found that when these compounds are used, they are strongly solvated with the polyamic acid due to the planar structure, so that they are replaced with polar organic solvents and have an effect of preventing coloring during high-temperature firing.

  The dielectric constant of the compound is 30 or more, more preferably 40 or more. The dipole moment of the compound is 3 Debye or more, more preferably 4 Debye or more.

Compounds used in the present invention, ethylene carbonate, propylene carbonate, Ru least one Der selected from butylene carbonate and γ- butyrolactone.

  Moreover, when the solid content of the polyimide precursor liquid is 100 parts by mass, the polar polymerization solvent is preferably in the range of 150 to 900 parts by mass and the cyclic structure compound is in the range of 15 to 750 parts by mass.

  Moreover, it is preferable that the said polyimide precursor is superposed | polymerized in the said polar polymerization solvent, and the said cyclic structure compound is added after that.

  The polyimide coating of the present invention preferably exhibits a transmittance of 50% or more when irradiated with light of 420 nanometers (nm) on a film or coating having a thickness of 50 ± 10 micrometers (μm). Preferably it is 60% or more, particularly preferably 70% or more.

The aromatic tetracarboxylic dianhydride monomer component of the present invention is BPADA represented by the chemical formula (A) .

Another aromatic tetracarboxylic dianhydride monomer component is BPDA represented by the chemical formula (B) .

Aromatic diamines of the present invention, the general formula (I) to thus represented ruby scan [substituted - amino phenyl] sulfone (substituted -DDS). Although it may be a meta form or a para form, it is preferably a para form. Para - Examples of substituted aromatic diamines include 4,4'-diaminodiphenyl sulfo down.

In producing the polyamic acid solution of the present invention, SO ₂ functional groups (for example, 4,4-DDS)
When a diamine containing is used, it is preferable to use a second diamine monomer together with it for the purpose of fading the color of the resulting polyimide and / or improving toughness. This second diamine monomer can be either a para- or meta-substituted aromatic diamine, an alicyclic diamine. Examples of meta-substituted aromatic diamines include bis [4- (3-aminophenoxy) phenyl] sulfone (BAPSM), 1,3-metaphenylenediamine (MPDA), 1,3-bis (3-aminophenoxy) Examples include benzene (m-ABP) and 3,4'-oxydianiline (3,4'-ODA). Examples of alicyclic diamines include cyclohexane diamine, isophorone diamine, norbornane diamine, and the like.

In the present invention, BPADA in which X represented by the chemical formula (B) is — (CH ₃ ) ₂ — has a melting point endothermic peak temperature by a differential scanning calorimeter (DSC) of 187 ° C. or more, and a melting point onset endotherm. Below the temperature, it is preferable that there is substantially no endotherm or exotherm. When such BPADA is used, the transparency can be further maintained.

When the compound represented by the chemical formula (A) is biphenyltetracarboxylic dianhydride (BPDA), the blending ratio of BPADA represented by the chemical formula (B) is BPDA: BP.
It is preferable that ADA = 9: 1 to 5: 5. If it is this range, toughness can be made high, maintaining transparency high.

  When other functional groups are introduced into the aromatic tetracarboxylic dianhydride, the cost tends to increase. In particular, when fluorine is introduced, the manufacturing cost is significantly increased. For this reason, biphenyltetracarboxylic dianhydride (BPDA) represented by the chemical formula (B) is preferable.

  In a preferred embodiment, the polyamic acid or coating solution of the present invention comprises the aromatic tetracarboxylic dianhydride (also referred to as bifunctional acid anhydride) component described above in an inert atmosphere at a temperature lower than 90 ° C. in a polar organic solvent. And an aromatic diamine monomer component is reacted or polymerized. The reaction time is 6 hours or more.

  When producing the polyamic acid or the coating solution, it is preferable to increase the degree of polymerization by reacting the bifunctional anhydride component and the diamine monomer component as much as possible in an equimolar ratio. Therefore, the bifunctional acid anhydride / diamine molar ratio is preferably maintained in the range of 0.9 to 1.1 / 1.0, more preferably 1.00 to 1.04 / 1.0. The molecular weight of the polyamic acid in the polyamic acid solution of the present invention is preferably 5,000 to 500,000, more preferably 15,000 to 100,000.

  Polar polymerization solvents useful in the present invention include, for example, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazo Examples include lysinone, N-methylcaprolactam, hexamethylphosphoric triamide, dimethyl sulfoxide, sulfolane and the like. A preferred polar polymerization solvent is N, N-dimethylacetamide (DMAC). These polar polymerization solvents can be used alone or as a mixture or mixed with other solvents such as toluene, xylene, that is, aromatic hydrocarbons.

The reaction mixture contains, in addition to the bifunctional anhydride component and diamine monomer component, processing or flow aids (eg, MODAFLOW that do not adversely affect the transparency and yellowness index properties of the resulting polyimide coating or film. ) (Registered trademark) flow aids), antioxidants, dyes, inorganic pigments (eg, titanium dioxide, TiO ₂ ), and fillers (eg, polytetrafluoroethylene, fluorinated ethylene / propylene copolymers) Can also be contained.

  In order to facilitate handling of the polyamic acid solution, the concentration of the polyamic acid in the solution is in the range of about 10 to 30% by weight, preferably about 20 to about 25% by weight, and the viscosity of the solution is about 1 to It is preferably in the range of about 5,000 poise.

  Once the polyamic acid solution is made, it can be cast or coated onto an optically useful article. Optically useful articles contemplated for use with the present invention include liquid crystal displays, electroluminescence, optical fiber cables, waveguides, solar cells, and electrophotographic devices described in JP 2003-5548 A And a transparent fixing film that transmits a part of the absorption wavelength light of the toner, and a transparent annular support for a photoreceptor used as an image recording method of an electrophotographic apparatus described in JP-A-58-153957. However, it is not limited to them.

  The polar organic solvent is removed from the polyamic acid solution upon completion of the casting or coating process, and the polyamic acid is chemically or thermally imidized into a polyimide.

In a preferred embodiment, 20-2 having a viscosity in the range of about 5 to about 2,500 poise.
The 5 wt% polyamic acid solution is cast at a prescribed thickness on a glass plate or stainless steel plate. The removal of the polar solvent and the imidization of the polyamic acid are then performed sequentially or simultaneously. In a further preferred embodiment, the polyamic acid solution is cast on the object surface and dried at a temperature of 80-120 ° C. for 30-120 minutes to form a film. The temperature is then raised to 200 ° C. and this temperature is maintained for 10 to 180 minutes. Thereafter, the temperature is raised to 250-300 ° C. and this temperature is maintained for 30-120 minutes to imidize the film into a polyimide film.

  Alternatively, the imide can be closed by a chemical imidization method. In a preferred embodiment, acetic anhydride and a tertiary amine are used as catalysts for ring closure. In a further preferred embodiment, a strong acid such as methanesulfonic acid is used as a catalyst and the azeotropic water is removed by using a cosolvent such as toluene.

  In another preferred embodiment, the polyamic acid solution of the present invention is applied as a paint to an optical fiber. In particular, the optical fiber is passed through an applicator and a 20-25 wt% polyamic acid solution having a viscosity in the range of about 5-25 poise is applied over the length of the fiber. Thereafter, removal of the polar catalyst and imidization of the polyamic acid are preferably performed by placing the coated optical fiber in an oven at a temperature zone of 120 ° C. to 300 ° C. in an oven from 0.3 meters / minute (m / min) to 9.3-12. It is performed by passing at a speed of 4 m / min.

  The resulting polyimide film or coating is essentially colorless and transparent. In a preferred embodiment, the film or coating exhibits a transmittance of at least 50% when irradiated with light of 420 nanometers (nm) to a film or coating having a thickness of 50 ± 10 micrometers (μm).

  Moreover, the glass transition temperature (Tg) of the preferable polyimide film of this invention is 200 degreeC or more, More preferably, it is 250 degreeC or more.

  The preferred polyimide coating of the present invention has a water absorption of 2.0% or less.

  At least one transparent film may be further formed on at least one surface of the polyimide coating. This is to improve the adhesion to the transparent conductive film described below without impairing the transparency. Examples of the transparent film include transparent thin films such as aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, tantalum oxide, and diamond-like carbon. These transparent films can be used as a single layer or laminated. A preferable film thickness is in the range of 50 nm to 5 μm. These transparent films can be formed by, for example, vacuum deposition, sputtering, ion plating, plasma CVD, or the like.

At least one transparent conductive film may be further formed on at least one surface of the polyimide film or the transparent film. The transparent conductive film preferably has an electrical resistivity of 1 × 10 ⁻² Ω · cm or less. Examples of the transparent conductive film include an indium-tin oxide alloy, and the film thickness is preferably in the range of 50 nm to 1 μm. This conductive film can be formed by, for example, vacuum deposition, sputtering, ion plating, plasma CVD, or the like. The film may be heat treated (annealed) at a high temperature of 170 ° C. or higher for a relatively short time to improve the transparency, heat resistance, and conductivity. Since the polyimide coating of the present invention has a high Tg, it can be annealed.

Various characteristics of the polyimide film produced in each example and comparative example were measured by the following measuring methods.
(1) Measurement of light transmittance The light transmittance of 420 nm was measured using a spectrophotometer UV-2550 manufactured by Shimadzu Corporation.
(2) Measurement of water absorption rate According to ASTM D570, the polyimide film is dried at a temperature of 150 ° C. for 30 minutes, and after measuring the weight (A), it is immersed in pure water for 24 hours, taken out, and the weight (B) is again measured. The water absorption was determined by the following equation.
Water absorption rate (%) = [(BA) / A] × 100
(3) X-ray photoelectron spectroscopy (XPS)
Using a Rigaku X-ray photoelectron spectrometer XPS-700, the polyimide surface was subjected to XPS analysis. The spectrum derived from the 1s orbital (01s) of oxygen obtained by XPS analysis was subjected to waveform separation on the assumption that each binding peak was Gaussian analysis, and the degree of imidization was evaluated.
(4) Glass transition temperature Using a dynamic viscoelastic device DM6100 manufactured by Seiko Instruments Inc., a sinusoidal load having an amplitude of 98 mN and a frequency of 1.0 Hz was applied to a polyimide film having a length of 8 mm and a width of 30 mm at 2 ° C. The glass transition temperature was measured by determining the storage elastic modulus and loss energy in the process of the rate of temperature increase per minute.
(5) Film thickness of polyimide film The film thickness was measured using the crystal vibration type film-forming controller CRTM-6000 by Nippon Vacuum Technology.
(6) Electric resistivity The electric resistivity was measured by a four-probe method according to JIS K 7194.
(7) Adhesion test
Measurement was performed using a Sebastian V-type tester manufactured by Quad group, using an aluminum stud pin with an epoxy resin adhesive and a ceramic backing plate with an epoxy resin adhesive.
(8) Measurement of toughness The test was repeated 10 times by folding the film with fingers, rubbing strongly with a nail to make a crease firmly, opening and flattening, and rubbing with a nail again to make a crease firmly. In this test, those that were cracked or torn were marked with x, and those that were not cracked were marked with ◯.
(9) Analysis of transparent conductive thin film / X-ray photoelectron spectroscopy (XPS)
The surface of the transparent conductive thin film formed on the polyimide surface was subjected to XPS analysis using a Rigaku X-ray photoelectron spectrometer XPS-700.
・ Thin film X-ray diffraction (XRD)
The surface of the transparent conductive thin film formed on the polyimide surface was subjected to XRD analysis using a thin film X-ray diffraction analyzer manufactured by Rigaku Corporation.
(10) Film thickness of transparent conductive thin film The film thickness of the transparent conductive thin film was calculated | required using the crystal vibration type film-forming controller CRTM-6000 of Nippon Vacuum Technology.

Example 1
(A) Synthesis of polyimide precursor (polyamic acid) liquid A 500 mL three-necked flask was equipped with a stirring rod and a nitrogen gas introduction tube equipped with a stirring blade made of polytetrafluoroethylene to form a polymerization vessel. Performed under a nitrogen atmosphere. 4,4′-Diaminodiphenyl sulfone (44DDS) sold as a diamine component under the trade name “Seika Cure S” as a diamine component so that the solid content of the polyimide precursor liquid is 28 mass%. 565 g (0.135 mol), N, N-dimethylacetamide (DMAC) sold by Mitsubishi Gas Chemical Company as a polymerization solvent 216.
0 g was added, 44DDS was completely dissolved in DMAC, and then biphenyltetrasole sold under the trade name “BPDA” by Mitsubishi Chemical Corporation as a bifunctional acid anhydride with a molar ratio of 1.03 to the diamine component. Carboxylic dianhydride (BPDA) 28.69 g (0.0976 mol) and 2,2-bis [4- (dicarboxyphenoxy) phenyl] propane sold by Shanghai Synthetic Resin Research Institute under the trade name “BPADA” 21.747 (0.0418 mol) of dianhydride (BPADA) was added as a solid over 5 minutes, reacted at room temperature for 1 hour, reacted at 40 ° C. for 12 hours, and had a viscosity of 205 poise. A polyimide precursor solution was obtained. Next, 36.0 g of propylene carbonate manufactured by Huntsman was added so that the cyclic structure compound would be 43 parts by mass when the solid content of the polyimide precursor liquid was 100 parts by mass. As shown in FIG. 1, the “BPADA” has a melting point endothermic peak temperature measured by a differential scanning calorimeter (DSC) of 189.96 ° C. and is substantially endothermic when it is lower than the melting point onset endothermic temperature (187.26 ° C.). There is no fever. This means that there are very few or no impurities in the low temperature region that adversely affect transparency.
(B) Manufacture of a polyimide film A polyimide precursor liquid is put into a desiccator, and 1.33 × 10 ³ Pa (10 mmH) therein.
The solution was degassed by holding at the pressure of g) for 1 hour. Thereafter, the degassed solution was cast on a peel-coated glass plate, and the thickness in the width direction of the cast film was made uniform through a draw bar having an adjustment gap. The cast glass plate is then placed in an oven and the film is cured by an imidization reaction at 80 ° C. for 45 minutes, then 120 ° C. for 30 minutes, then 150 ° C. for 30 minutes, and then 300 ° C. for 30 minutes. I let you. Thereafter, the glass plate was taken out of the oven, cooled to room temperature, and the film was peeled off from the glass plate. The light transmittance and water absorption of this polyimide film were measured. The glass transition temperature was 304 ° C.

(Examples 2 to 6)
In Example 1, a polyimide precursor solution and a polyimide film were prepared in the same manner as in Example 1 except that the cyclic structure compound shown in Table 2 was added in the parts by mass shown in Table 1, and light transmission of this polyimide film was made. The rate and water absorption were measured. The glass transition temperature of the polyimide film was 304 ° C. for all.

(Comparative Examples 1-8)
In Example 1, except having added the compound of Table 3 by the mass part of Table 1, a polyimide precursor liquid and a polyimide film were produced like Example 1, and the light transmittance of this polyimide film and The water absorption was measured.

  The above conditions and results are summarized in Table 1, Table 2 shows the structural formulas of the additives in Examples 1 to 6 of the present invention, and Table 3 shows the structural formulas of the additives in Comparative Examples 1 to 8.

(Remarks) The numerical value of the additive part by mass indicates the part by mass of the additive when the polyimide precursor (solid content) is 100 parts by mass.

  As is clear from the above results, Examples 1 to 6 of the present invention not only have a high glass transition temperature, but also have high light transmittance and transparency compared to Comparative Examples 1 to 8 (prior art). As a result of the XPS analysis, the imidization was further advanced, so that a polyimide film having a low water absorption rate could be obtained.

(Example 7)
(1) Aromatic diamine The aromatic diamine is 4,4-DDS, which is a para-form of the above chemical formula (I): 4,4 ′ sold under the trade name “Seika Cure-S” by Wakayama Seika Kogyo Co., Ltd. -Diaminodiphenyl sulfone was used.
(2) Alicyclic diamine As the alicyclic diamine, NBDA: Norbornane diamine sold under the trade name “NBDA” from Mitsui Chemicals, Inc. was used.
(3) Bifunctional acid anhydride As the bifunctional acid anhydride, BPDA of the above chemical formula (A): manufactured by Mitsubishi Chemical Corporation, trade name “BP”
Biphenyltetracarboxylic dianhydride monomer sold by DA "and 2,2-bis [4- (dicarboxyphenoxy) phenyl] propane dianhydride (BPADA) of the above chemical formula (B): Shanghai Synthetic Resin The product name "BPADA" manufactured by Research Laboratory was used.
( 4 ) Polar organic solvent As the polar organic solvent, DMAC: N, N-dimethylacetamide sold by Mitsubishi Gas Chemical Company was used.
( 5 ) Lactone Compound As the lactone compound, γ-butyrolactone manufactured by Mitsubishi Chemical Corporation was used.
( 6 ) Other dilution solvents Tetrahydrofuran and butyl cellosolve were manufactured by Wako Pure Chemical Industries, and isophorone was manufactured by Daicel Chemical.
( 7 ) Sample preparation and test method (a) Synthesis of polyamic acid (polyimide precursor) solution A fixed amount of diamine monomer and DMAC solvent were charged into the reactor, and a nitrogen atmosphere until the diamine monomer was completely dissolved in DMAC solvent. Stirred under and refluxed at 40 ° C. Thereafter, a certain amount of bifunctional anhydride monomer was added to the reactor to form a polyamic acid solution. The molar ratio of the bifunctional acid anhydride component and the diamine monomer component used to produce the polyamic acid solution was 1.03 / 1.0. The mixing ratio of the solvent and the polyamic acid solid content was such that the solid content was 28% by mass. After completion of the polymerization reaction, a predetermined amount of γ-butyrolactone was added. When the solid content of the polyimide precursor liquid was 100 parts by mass, 257 parts by mass of the polar polymerization solvent and additives such as γ-butyrolactone were added as shown in Table 4.
(B) Manufacture of a polyimide film The polyamic acid solution was put into the desiccator, and it hold | maintained at the pressure of 10 mmHg for 1 hour, and degassing of the solution was performed. Thereafter, the degassed solution was cast on a peel-coated glass plate, and the thickness in the width direction of the cast film was made uniform through a draw bar having an adjustment gap. The cast glass plate is then placed in an oven and the film is cured by an imidization reaction at 80 ° C. for 45 minutes, then 120 ° C. for 30 minutes, then 150 ° C. for 30 minutes, and then 300 ° C. for 30 minutes. I let you. Thereafter, the glass plate was taken out of the oven, cooled to room temperature, and the film was peeled off from the glass plate. Thereafter, light transmittance, toughness, and glass transition temperature were measured. The results are shown in Table 4.

(Examples 8 to 15)
In Example 7, a polyimide precursor solution and a polyimide film were prepared in the same manner as in Example 7 except that the molar ratio of diamine or bifunctional anhydride was changed as described in Table 4, and the light transmission of this polyimide film The rate, toughness and glass transition temperature were measured. The results are listed in Table 4.

(Example 16 , Reference example )
In Example 7, the polyimide precursor liquid and the polyimide were changed in the same manner as in Example 7 except that the diamine was changed to 4,4-DDS / NBDA in the molar ratio shown in Table 4 and the bifunctional acid anhydride was changed to BPDA only. A film was prepared, and the light transmittance, toughness, and glass transition temperature of the polyimide film were measured. The results are listed in Table 4.

(Example 17 , Reference example )
(A) Synthesis of polyimide precursor (polyamic acid) liquid A 500 mL three-necked flask was equipped with a stirring rod and a nitrogen gas introduction tube equipped with a stirring blade made of polytetrafluoroethylene to form a polymerization vessel. Performed under a nitrogen atmosphere. NBDA (28.317 g, 0.184 mol) as a diamine component and DMAC (216.0 g) as a polymerization solvent were added and stirred well so that the solid content of the polyimide precursor liquid would be 28% by mass. As a 0.03-fold bifunctional acid anhydride, 55.683 g (0.189 mol) of BPDA was added as a solid over 5 minutes. After 15 minutes, the reaction solution became yogurt-like. Soon, the reaction temperature rapidly increased to about 60 ° C., and the solution turned from a yogurt to a viscous liquid. Furthermore, it was made to react at 40 degreeC for 12 hours, and the precursor liquid was obtained. Next, when the solid content of the polyimide precursor liquid was 100 parts by mass, 36.0 g of γ-butyrolactone was added so that the cyclic structure compound would be 43 parts by mass. A polyimide film was produced in the same manner as in Example 7, and the light transmittance, toughness, and glass transition temperature of this polyimide film were measured. The results are listed in Table 4.

(Remarks 1) Regarding the molar ratio, the upper part is an acid anhydride and the lower part is a diamine.
(Remarks 2) The numerical value in () in the column of additive indicates the mass part of the additive when the polyimide precursor (solid content) is 100 mass parts.

  In Table 4, since Experiment Nos. 1 to 8 were within the scope of the present invention, both transparency and toughness were high. On the other hand, since Experiment Nos. 9 to 16 did not add a lactone compound, the transparency was lower than that of Examples of the present invention.

(Example 18)
A 75 μm-thick polyimide film prepared from the polyimide precursor liquid of Example 1 on the substrate side with indium oxide doped with 5% by mass of tin on the sputtering electrode of a radio frequency (RF) magnetron sputtering apparatus is attached at a position of 100 mm from the target. It was. Next, rough evacuation was performed using an oil rotary pump, and evacuation was performed to 2.0 × 10 ⁻⁴ Torr using an oil diffusion pump. Next, 97 sccm of argon gas and 3 sccm of oxygen gas were introduced and maintained at 1.0 × 10 ⁻² Torr. Next, a transparent conductive thin film made of indium tin oxide (ITO) having a thickness of 300 nm is formed by sputtering with an RF traveling wave of 250 W and an RF reflected wave of 0 W for about 30 minutes, and annealed at 200 ° C. in the atmosphere to be transparent. A conductive film was obtained.

The light transmittance at 380 nm to 780 nm of this transparent conductive thin film was 80% or more. The transparent conductive thin film did not peel off in the adhesion test. The electrical resistivity of the transparent conductive film was 1.7 × 10 ⁻⁴ Ωcm.

Example 19
A silicon target was attached to the sputtering electrode of a radio frequency (RF) magnetron sputtering apparatus, and a polyimide film having a thickness of 50 μm prepared from the polyimide precursor liquid of Example 1 was attached to the substrate at a position 100 mm from the target. Next, rough evacuation was performed using an oil rotary pump, and evacuation was performed to 2.0 × 10 ⁻⁴ Torr using an oil diffusion pump. Next, nitrogen gas was introduced at 40 sccm and argon gas was introduced at 60 sccm to maintain 1.0 × 10 ⁻² Torr. Next, a transparent film made of silicon oxynitride (SiO _0.90 N _0.58 ) was formed to a thickness of 110 nm on the polyimide film by sputtering with an RF traveling wave of 400 W and an RF reflected wave of 0 W for about 30 minutes. SiO _0.90 N _0.58 was confirmed by XPS and XRD analysis. Even when a transparent film of silicon oxynitride was formed, the light transmittance was 76.9%, which was almost the same as in Example 1.

  Next, a transparent conductive thin film was formed on the silicon oxynitride transparent film in the same manner as in Example 18.

The light transmittance at 380 nm to 780 nm of this transparent conductive thin film was 80% or more. The transparent conductive thin film did not peel off in the adhesion test. The electrical resistivity of the transparent conductive film was 1.7 × 10 ⁻⁴ Ωcm.

  Next, a transparent conductive thin film was formed on the silicon oxynitride transparent film in the same manner as in Example 18.

The light transmittance at 380 nm to 780 nm of this transparent conductive thin film was 80% or more. The transparent conductive thin film did not peel off in the adhesion test. The electrical resistivity of the transparent conductive film was 1.7 × 10 ⁻⁴ Ωcm.

The thermal analysis data by the differential scanning calorimeter (DSC) of BPADA used in Examples 1-7 of this invention. The O1s spectrum figure in the XPS analysis of the polyimide obtained in Example 1 of this invention. The O1s spectrum figure in the XPS analysis of the polyimide obtained by the comparative example 1. FIG.

Claims (10)

At least one tetracarboxylic dianhydride or derivative thereof;
At least one diamine or derivative thereof;
A polyimide precursor liquid composition comprising a polar polymerization solvent,
Furthermore, it includes a cyclic structure compound having a 5-membered ring structure containing a carbonyl group (C═O bond) different from the polar polymerization solvent, and the cyclic structure compound has a boiling point of 200 ° C. or higher, and includes carbon, hydrogen and At least one cyclic structure compound selected from ethylene carbonate, propylene carbonate, butylene carbonate and γ-butyrolactone , which is composed of oxygen atoms and does not contain nitrogen, phosphorus, and sulfur heteroatoms;
The tetracarboxylic dianhydride is a compound represented by the following chemical formula (A) and a compound represented by the chemical formula (B),
The said diamine is a compound shown by following Chemical formula (I), The polyimide precursor liquid composition characterized by the above-mentioned.

Wherein when the solid content of the polyimide precursor liquid is 100 mass parts, the polar polymerization solvent is 150 to 900 parts by weight, and a polyimide precursor solution of claim 1 wherein the cyclic structure compound is in the range of 15 to 750 parts by weight Composition The polyimide precursor, the polar polymer is polymerized in a solvent, the polyimide precursor solution composition then the cyclic structure compound according to claim 1 or 2 is added. The polyimide film which made the imide conversion of the polyimide precursor liquid composition of any one of Claims 1-3 . Said polyimide coating, when irradiated with light of 420 nm to the film or coating of 50 ± 10 micrometers thick (μm) (nm), the polyimide of claim 4 showing a transmittance of 50% or more Coating. The polyimide film according to claim 4 , wherein a glass transition temperature (Tg) of the polyimide film is 200 ° C. or higher. The polyimide film according to claim 4 , wherein the polyimide film has a water absorption of 2.0% or less. The polyimide film according to claim 4 , wherein at least one transparent film is further formed on at least one surface of the polyimide film. The polyimide film according to claim 4 or 8 , wherein at least one transparent conductive film is further formed on at least one surface of the polyimide film or the transparent film. The polyimide film according to claim 9 , wherein the transparent conductive film has an electrical resistivity of 1 × 10 ⁻² Ω · cm or less.

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