KR20090053567A - Polyimide resin and film - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to polyimide resins and films comprising imides of polyamic acids obtained from diamines and dianhydrides and indium-tin mixed oxides (ITOs), which are colorless and transparent while exhibiting electrical properties, mechanical properties and heat resistance. Excellent polyimide resins and films can be provided.

Description

Polyimide Resin and Film

The present invention relates to polyimide resins and films.

In general, the polyimide resin refers to a high heat-resistant resin prepared by solution polymerization of an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to prepare a polyamic acid derivative, followed by ring closure dehydration at high temperature for imidization. In order to prepare a polyimide resin, pyromellitic dianhydride (PMDA) or biphenyltetracarboxylic dianhydride (BPDA) is mainly used as an aromatic dianhydride component, and oxydianiline (ODA), p-phenylene diamine (p-PDA), m-phenylene diamine (m-PDA), methylenedianiline (MDA), bisaminophenylhexafluoropropane (HFDA), etc. are mainly used.

Polyimide resin is an insoluble and insoluble ultra high heat resistant resin, and has excellent characteristics such as heat oxidation resistance, heat resistance, radiation resistance, low temperature property, chemical resistance, and so on. It is used in a wide range of fields in electronic materials such as insulating films, semiconductors, and electrode protective films of TFT-LCDs.

However, polyimide resins are colored brown or yellow due to the high aromatic ring density, and thus have a low transmittance in the visible region and a yellow-based color, thus making it difficult to be used in applications requiring transparency due to low light transmittance.

In order to solve this problem, a method of polymerizing the monomer and the solvent by high purity has been attempted, but the improvement of the transmittance is not large.

U.S. Patent No. 553480 describes a method of using an aliphatic ring-based dianhydride component instead of an aromatic dianhydride, and compared to the purification method, there was an improvement in transparency and color when solution or film was formed, but also an improvement in permeability. There was a limit to the high permeability was not satisfactory, and also resulted in degradation of thermal and mechanical properties.

See also U.S. Pat.Nos. 4,595,548,4603061, 4,464,824,4895972, 52,18083, 5,345,3, 52,18077, 53,670, 46,337. No. 5986036, 6262328 and Korean Patent Publication No. 2003-0009437 are monomers having a curved structure connected to a linking group, such as -O-, -SO _2- , CH ₂ -and the m-position rather than the p-position A report has been made of a novel polyimide structure having improved transmittance and color transparency using aromatic dianhydride dianhydrides having substituents such as -CF ₃ and aromatic diamine monomers, without increasing the thermal properties significantly. Mechanical properties, yellowness and visible light transmittance have been insufficient to be used as a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, and a base layer for flexible displays.

In addition, the conductive film or material including the conventional conductive carbon black or the metal-based conductive filler was virtually impossible to apply to the transparent material due to the opacity.

The development of such a low yellow polyimide film was not only sluggish but also pioneered in the field of application. For example, a colorless transparent and conductive polyimide material can be used as a transparent electrode for flexible displays, and a colorless and transparent heat resistant polyimide material is an antistatic film, an electromagnetic shielding film, and a transparent transparent planar heating element for windows of automobiles and buildings. It may be applied to such as, but does not satisfy the physical properties required in the application field. Therefore, if it satisfies the colorless and transparent properties in addition to the high heat resistance of the polyimide film, all electronic products including the display field can be protected due to the advantages of maintaining the color inherent to the contact or adhesive product applied and blocking harmful electromagnetic waves. It is likely to be applied to.

On the other hand, in the situation where next-generation displays are pursuing low cost, large area, light weight, and flexible, attempts to use plastics lighter than glass as substrate materials are actively underway. In addition, in the case of the ITO transparent electrode, a problem such as a sudden increase in the electrode surface resistance due to electrode breakage due to the bending of the electrode substrate occurs, so that the demand for a plastic material having less such a problem is increasing.

Recently, development of transparent electrodes using expensive conductive materials, such as carbon nanotubes, in general transparent polymer materials, such as silicone, nylon, acrylic, and epoxy, has been under development. This is because the reason that the insulating support film should be thick is generated, and the support film should be expensive film having high mechanical properties of insulation and low moisture permeability.

On the other hand, as a colorless transparent conductive film, a film in which an indium-tin oxide film is formed on a polyethylene terephthalate plastic film is commercially available and has excellent performance in visible light, but its glass transition temperature is only about 70 ° C. It has the disadvantage of having low level of heat resistance which causes. This low level of heat resistance provides a fundamental cause of deterioration in durability and reliability when applied to electronics. In addition, the film formed with the dry or wet indium-tin oxide film is capable of energizing through the surface, but not in the thickness direction due to the non-conductivity of the base film, which is a design limitation in manufacturing the electrode circuit. have. In addition, it is difficult to apply to an electronic component requiring ductility due to the easily cracked properties of the indium-tin oxide film formed as a thick film, and on the contrary, when the thin film is thin, the electrical resistance increases.

Therefore, the present invention is to provide a polyimide resin and a film that is colorless and transparent, and excellent in electrical properties, mechanical properties and heat resistance.

Accordingly, the present invention provides a preferred embodiment of 2,2-bis [4- (4-aminophenoxy) -phenyl] propane (6HMDA), 2,2'-bis (trifluoromethyl) -4,4'- Diaminobiphenyl (2,2'-TFDB), 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (3,3'-TFDB), 4,4'-bis (3-aminophenoxy) diphenylsulfone (DBSDA), bis (3-aminophenyl) sulfone (3DDS), bis (4-aminophenyl) sulfone (4DDS), 1,3-bis (3-aminophenoxy) Benzene (APB-133), 1,4-bis (4-aminophenoxy) benzene (APB-134), 2,2'-bis [3 (3-aminophenoxy) phenyl] hexafluoropropane (3- BDAF), 2,2'-bis [4 (4-aminophenoxy) phenyl] hexafluoropropane (4-BDAF), and one or more diamines selected from oxydianiline (ODA), and 2,2-bis (3,4-Dicarboxyphenyl) hexafluoropropane dianhydride (FDA), 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene- 1,2-dicarboxylic anhydride (TDA), 4,4 ′-(4,4 Isopropylidenediphenoxy) bis (phthalic anhydride) (HBDA), 3,3 '-(4,4'-oxydiphthalic dianhydride) (ODPA) and 3,4,3', 4 Provided are a polyimide resin comprising imide of polyamic acid and indium-tin mixed oxide (ITO) obtained from at least one dianhydride selected from '-biphenyltetracarboxylic dianhydride (BPDA).

The polyimide resin according to the embodiment may include 2 to 100 parts by weight of indium-tin mixed oxide (ITO) based on 100 parts by weight of the polyamic acid solid content.

In the polyimide resin according to the embodiment, the indium-tin mixed oxide (ITO) may contain 80 to 95% by weight of indium oxide (In ₂ O ₃ ) and 5 to 20% by weight of tin oxide (SnO ₂ ). .

In another aspect, the present invention provides a polyimide film comprising the polyimide resin according to the above embodiment.

The polyimide film according to the embodiment may have an average transmittance of 70% or more at 380 to 780 nm when measuring transmittance with a UV spectrometer based on a film thickness of 25 to 100 μm.

The polyimide film according to the embodiment may have a yellowness of 15.0 or less based on a film thickness of 25 to 100 μm.

The polyimide film according to the embodiment may have a volume resistance of 10 ¹ to 10 ¹² Ω · cm.

Polyimide film according to the embodiment may have a surface resistance of 10 ¹ ~ 10 ¹² Ω / □.

The polyimide film according to the embodiment may have a volume resistance of 10 ¹ to 10 ⁶ Ω · cm.

The polyimide film according to the embodiment may have a volume resistance of 10 ⁶ to 10 ¹² Ω · cm.

In another aspect, the present invention provides an electronic component comprising the polyimide film.

In another aspect, the present invention provides a transparent electrode comprising the polyimide film.

In another aspect, the present invention provides an electromagnetic shielding film comprising the polyimide film.

In another aspect, the present invention provides an antistatic film comprising the polyimide film.

The present invention also provides a tubular belt comprising the polyimide film.

The present invention can provide a polyimide resin and a film that can be used in a field where transparency and conductivity are required by providing a polyimide resin and a film that is colorless and transparent and excellent in electrical properties, mechanical properties, and heat resistance.

Hereinafter, the present invention will be described in more detail.

The polyimide resin of the present invention is a colorless and transparent that includes an imide and an indium-tin mixed oxide (ITO) which are imidized after copolymerizing diamines and dianhydrides to obtain a polyamic acid solution that is a precursor of polyimide. Polyimide resin.

Colorless transparent polyimide resin of the present invention is preferably excellent in transparency to visible light, the average transmittance at 380 ~ 780nm 70% or more when measured transmittance with a UV spectrometer based on the film thickness 25 ~ 100㎛, yellow It is preferable that the figure is 15.0 or less.

The polyimide resin and the film of the present invention having excellent transparency to the visible light have limited use due to the yellow color of the existing polyimide film, that is, a diffusion plate and a coating film such as a protective film or a TFT-LCD, such as a TFT- It can be used in fields requiring transparency such as interlayer, gate insulator and liquid crystal alignment film in LCD, and it is possible to manufacture high-contrast TFT-LCD by contributing to increase of aperture ratio when applying transparent polyimide as liquid crystal alignment film. It can also be used for flexible display substrates. In addition, since the polyimide resin has a glass transition temperature of 200 ° C. or more and excellent heat resistance, the polyimide resin does not easily cause dimensional deformation and does not deteriorate durability and reliability even when used in the electronic device described above.

The dianhydrides used for this purpose are 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (FDA), 4- (2,5-dioxotetrahydrofuran-3-yl. ) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), 4,4 '-(4,4'-isopropylidenediphenoxy) bis (phthalic Anhydride) (HBDA), 3,3 '-(4,4'-oxydiphthalic dianhydride) (ODPA) and 3,4,3', 4'-biphenyltetracarboxylic dianhydride ( Preferably at least one selected from BPDA).

In addition, the diamines used in the present invention are 2,2-bis [4- (4-aminophenoxy) -phenyl] propane (6HMDA), 2,2'-bis (trifluoromethyl) -4,4'- Diaminobiphenyl (2,2'-TFDB), 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (3,3'-TFDB), 4,4'-bis (3-aminophenoxy) diphenylsulfone (DBSDA), bis (3-aminophenyl) sulfone (3DDS), bis (4-aminophenyl) sulfone (4DDS), 1,3-bis (3-aminophenoxy) Benzene (APB-133), 1,4-bis (4-aminophenoxy) benzene (APB-134), 2,2'-bis [3 (3-aminophenoxy) phenyl] hexafluoropropane (3- BDAF), 2,2'-bis [4 (4-aminophenoxy) phenyl] hexafluoropropane (4-BDAF) and oxydianiline (ODA).

The dianhydrides and diamines described above are dissolved in an organic solvent in an equimolar amount to react to prepare a polyamic acid solution.

The solvent for the solution polymerization of the monomers described above is not particularly limited as long as it is a solvent that dissolves the polyamic acid. Known reaction solvents selected from m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), acetone, diethyl acetate One or more polar solvents are used. In addition, low boiling point solutions such as tetrahydrofuran (THF), chloroform or low absorbing solvents such as γ-butyrolactone may be used.

On the other hand, the polyimide film of the present invention includes an indium-tin mixed oxide (ITO) in order to improve the electrical properties, the electrical properties can be adjusted according to the content of the indium-tin mixed oxide, indium-tin mixed oxide It can also be controlled by adjusting the content of indium oxide and tin oxide on its own. The indium-tin mixed oxide (ITO) may preferably contain 80 to 95% by weight of indium oxide (In ₂ O ₃ ) and 5 to 20% by weight of tin oxide (SnO ₂ ). The indium-tin mixed oxide may be in powder form, the size of which depends on the material used and the reaction conditions, preferably having an average minimum diameter of 30 to 70 nm and an average maximum diameter of 60 to 120 nm.

In the polyimide film of the present invention, the volume resistance is 10 ¹ to 10 ¹² Ω · cm, and the surface resistance is 10 ¹ to 10 ¹² Ω / □. The volume resistivity is 10 ¹ ~ 10 ⁶ Ω · cm is may be applied as a transparent electrode or electromagnetic shielding material, transparent planar heating element materials, such ^{as, 10 6 ~ 10 12 Ω ·} cm is applicable as an antistatic material and the intermediate transfer belt for a printer have. Therefore, the polyimide film of the present invention can be applied to an intermediate transfer belt for a printer requiring anticonductivity, an antistatic film, an electromagnetic shielding film, and an electrode material requiring conductivity.

The indium-tin mixed oxide may be dispersed in a polyamic acid solution, and may include 2 to 100 parts by weight of indium-tin mixed oxide (ITO) based on 100 parts by weight of the polyamic acid solid content. If the content is less than 2 parts by weight, it is impossible to realize meaningful conductivity. If the content is more than 100 parts by weight, the ductility of the film is lowered, and thus it is difficult to be included in the flexible substrate.

Although the addition method of an indium-tin mixed oxide is not specifically limited, For example, the method of adding to the polyamic-acid solution before superposition | polymerization or in superposition | polymerization, the method of kneading the indium-tin mixed oxide after completion | finish of polyamic-acid polymerization, indium-tin The method etc. which prepare the dispersion liquid containing a mixed oxide, and mix this with a polyamic-acid solution are mentioned. At this time, the dispersibility of the indium-tin mixed oxide is affected by the acid-base and viscosity of the dispersion solution, and the dispersion process must be sufficiently performed because it affects the uniformity of the conductivity and the transmittance of visible light. Preferred dispersion methods include three rolls, an ultrasonic disperser, a homogenizer, a ball mill and the like.

The method for preparing a polyimide film from the obtained polyamic acid solution may be a conventionally known method, that is, the film can be obtained by imidizing the polyamic acid solution by casting on a support, but is not limited thereto.

The imidation method applicable at this time can be applied in combination with the thermal imidation method, the chemical imidation method, the thermal imidation method, and the compound imidation method. The chemical imidization method is a method of injecting an imidization catalyst represented by a dehydrating agent represented by an acid anhydride such as acetic anhydride and tertiary amines such as isoquinoline, β-picolin and pyridine into a polyamic acid solution. In the case of using the thermal imidization method or the thermal imidization method together with the chemical imidization method, the heating conditions of the polyamic acid solution may vary depending on the kind of the polyamic acid solution, the thickness of the polyimide film to be produced, and the like.

When explaining the production example of the polyimide film in the case of using the thermal imidation method and the chemical imidation method more specifically, 80-200 degreeC, after casting a dehydrating agent and an imidation catalyst in a polyamic-acid solution, and casting on a support body, Preferably, the polyamic acid film in the gel state is obtained from the support after being partially cured and dried by heating at 100 to 180 ° C. to activate the dehydrating agent and the imidization catalyst, and the film in the gel state at 5 ° C. to 200 ° C. to 400 ° C. A polyimide film can be obtained by heating for 400 seconds.

Although the thickness of the polyimide film obtained is not specifically limited, It is preferable that it is the range of 10-250 micrometers in consideration of an application field, More preferably, it is 25-150 micrometers.

As described above, since the polyimide resin and the film of the present invention are colorless and have excellent electrical properties, they can be applied to materials requiring similar electrical properties such as substrates for display devices, antistatic films, and electromagnetic shielding films.

Hereinafter, examples of the present invention will be described in more detail, but the scope of the present invention is not limited to these examples.

<Example 1>

The reactor was filled with 34.1904 g of N, N-dimethylacetamide (DMAc) while passing nitrogen through a 100 ml 3-Neck round bottom flask equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a cooler. 0.450 g (5 parts by weight of solids content in the polyamic acid solution) was added to a tin mixed oxide powder (Shanghai Hujeongna Nano, ITO-P100, In ₂ O ₃ : SnO ₂ = 90: 10), and an ultrasonic disperser (200 W, 40 kHz) was added. , Manufacturer ULTEC, Korea) was dispersed in the solution for 1 hour, the temperature of the reactor was lowered to 0 ℃ 6HMDA 4.1051g (0.01 mol) was dissolved to maintain this solution at 0 ℃. 4.4425 g (0.01 mol) of 6FDA was added thereto and stirred for 1 hour to completely dissolve 6FDA. At this time, the concentration of solids was 20% by weight. After that, the solution was allowed to stand at room temperature and stirred for 8 hours. At this time, the solution viscosity at 23 degreeC was obtained the polyamic-acid solution of 850 poise.

The polyamic acid solution was coated on a flat glass plate with a bar-a coater, and then heated at a rate of 2 ° C./min at a temperature ranging from 40 ° C. to 400 ° C., and at 200 ° C. and 300 ° C. for 30 minutes to 2 minutes. It was heated for 3 to 8 hours while stabilizing through a time period of time to obtain a 50 μm thick polyimide film.

<Example 2>

The same procedure as in Example 1 was performed except that 4.50 g (50 parts by weight based on the solids content in the polyamic acid solution) of the indium-tin mixed oxide powder was added.

<Example 3>

Except for changing the mixing ratio of the indium-tin mixed oxide powder in Example 2 (In ₂ O ₃ : SnO ₂ = 85:15) it was carried out in the same manner.

<Example 4>

In Example 1, the kind of diamine was 1,4-bis (4-aminophenoxy) benzene (Mitsui Chemical Co., Ltd., APB-NP), and the same ratio except that the equivalent ratio of dianhydride and diamine was adjusted to 1: 0.998. The polyimide film was obtained by the method.

Comparative Example 1

The same procedure was followed as in Example 1 except that carbon black (CABOT, VULCAN XC72) was added instead of the indium-tin mixed oxide powder.

Comparative Example 2

After the reactor was filled with 87 g of N, N-dimethylacetaamide (DMAc) while passing nitrogen through a 200 ml 3-Neck round bottom flask equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler, the reactor temperature The solution was maintained at 25 ° C. and 6.848 g of BTDA (DICEL) was dissolved to maintain this solution at 25 ° C. 6.152 g of APB (Mitsui Chemical, APB-N) was added thereto, and stirred for 1 hour to completely dissolve the APB. At this time, the concentration of solids was 13% by weight, and 0.450 g of indium-tin mixed oxide powder (Shanghai Hujeongna Nano, ITO-P100, In2O3: SnO2 = 90: 10) (5% by weight of the solids content in the polyamic acid solution) ) Was added and reacted for 1 hour at room temperature while dispersing in the solution through an ultrasonic disperser. After that, the solution was allowed to stand at room temperature and stirred for 8 hours. At this time, the solution viscosity at 23 degreeC was obtained the polyamic-acid solution of 230 poise.

Thereafter, a polyimide film was obtained in the same manner as in Example 1.

The polyimide resin imidized while raising the temperature at a rate of 2 ° C./min in a temperature range of 40-400 ° C. before the polyamic acid solution containing the indium-tin mixed oxide powder was prepared in the above Examples and Comparative Examples. The physical properties were evaluated in the following manner.

The physical properties of the polyimide films prepared in Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Table 1 below.

(1) volume resistance and surface resistance

Measuring Device: Hiresta UP, Probe UR-100 (Dia Instrument)

Measuring Method: Applied Voltage 10V, 100V, 250V

The surface resistance unit is Ω / □ and the volume resistance unit is Ω-cm. The measurement environment is 25 ° C and 55 RH%. The resistivity meter is marked under for 10 ⁴ Ω / □ or 10 ⁴ Ω-cm or less. As such, a product having a resistance value of under can be applied as a conductive product.

(2) transmittance

The prepared film was measured for visible light (380-780 nm) and transmittance of 550 nm wavelength using a UV spectrometer (Varian, Cary 100). The measurement environment is 25 ° C and 55 RH%.

(3) yellowness

The prepared film was measured using a UV spectrometer (Varian, Cary 100) to measure the yellowness according to ASTM E313 standard.

(4) Volume resistivity and surface resistivity for Example 2

In Table 1, specific resistance values were measured using a multi-functional tester (MI-2086-EU) manufactured by METREL (Europe) for Example 2 having a surface resistance of 10 ⁴ Ω / □ or less and a volume resistance of 10 ⁴ Ω · cm or less. As a result, the surface resistance is 1.2x10 ² Ω / □ at 1kV applied voltage. The volume resistance was 6.2x10 ² Ωcm.

As a result of the physical property evaluation, it can be seen that the polyimide film of the present invention has good conductivity and transparency. In the case of Example 2, it can be seen that the surface resistance and the volume resistance are very low, and the conductivity is greatly improved.

On the other hand, it was confirmed that the conductive polyimide film having excellent transparency obtained in the above example retains volume resistance and surface resistance even after being rotated while being rotated while being wound in a tube shape having a diameter of 10 mm. Therefore, it can be seen that the polyimide film of the present invention can be applied to tubular belts such as intermediate transfer belts which are continuously rotated around a plurality of rollers.

Claims (15)

2,2-bis [4- (4-aminophenoxy) -phenyl] propane, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,3'-bis ( Trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-bis (3-aminophenoxy) diphenylsulfone, bis (3-aminophenyl) sulfone, bis (4-aminophenyl) sulfone , 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2'-bis [3 (3-aminophenoxy) phenyl] hexafluoropropane , 2,2'-bis [4 (4-aminophenoxy) phenyl] hexafluoropropane and at least one diamine selected from oxydianiline and 2,2-bis (3,4-dicarboxyphenyl) hexa Fluoropropane dianhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, 4 , 4 '-(4,4'-isopropylidenediphenoxy) bis (phthalic anhydride), 3,3'-(4,4'-oxydiphthalic dianhydride) and 3,4,3 ',4 - a polyimide resin containing a tin mixed oxide (ITO) - biphenyl tetracarboxylic dianhydride rigs hydroxy imide cargo and the indium of the polyamic acid obtained from the selected one or more dianhydride high dry Drew of fluoride. The method of claim 1, A polyimide resin comprising 2 to 100 parts by weight of indium-tin mixed oxide (ITO) based on 100 parts by weight of a polyamic acid solid content. The method of claim 1, Indium-tin mixed oxide (ITO) is a polyimide resin, characterized in that it contains 80 to 95% by weight of indium oxide (In ₂ O ₃ ) and 5 to 20% by weight of tin oxide (SnO ₂ ). The polyimide film containing the polyimide resin of any one of Claims 1-3. The method of claim 4, wherein Polyimide film, characterized in that the average transmittance at 380 ~ 780nm 70% or more when measuring the transmittance with a UV spectrometer based on the film thickness 25 ~ 100㎛. The method of claim 4, wherein Polyimide film, characterized in that the yellowness is 15.0 or less based on the film thickness 25 ~ 100㎛. The method according to any one of claims 4 to 6, A polyimide film having a volume resistance of 10 ¹ to 10 ¹² Ω · cm. The method according to any one of claims 4 to 6, A polyimide film having a surface resistance of 10 ¹ to 10 ¹² Ω / □. The method of claim 7, wherein A polyimide film having a volume resistance of 10 ¹ to 10 ⁶ Ω · cm. The method of claim 7, wherein A polyimide film having a volume resistance of 10 ⁶ to 10 ¹² Ω · cm. An electronic component comprising the polyimide film of any one of claims 4 to 6. The transparent electrode containing the polyimide film of Claim 9. An electromagnetic shielding film comprising the polyimide film of claim 9. An antistatic film comprising the polyimide film of claim 10. A tubular belt comprising the polyimide film of claim 10.