KR101292993B1 - Polyimide resin, and liquid crystal alignment layer and polyimide film using the same - Google Patents

Abstract

The present invention relates to a polyimide resin and a liquid crystal alignment film and a film using the same, which is colorless and transparent, and has excellent mechanical and thermal stability properties, such as a semiconductor insulating film, a TFT-LCD insulating film, a transparent electrode film, a passivation film, a liquid crystal alignment film, and optical communication. A polyimide resin usable in various fields such as a material, a solar cell protective film, a flexible display substrate, and a liquid crystal alignment film and film using the same.

Description

Polyimide resin, and liquid crystal alignment layer and polyimide film using the same}

The present invention relates to a polyimide resin and a liquid crystal alignment film and a film using the same, and more particularly, to a colorless transparent polyimide resin and a liquid crystal alignment film and a film using the same.

In general, the polyimide (PI) 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, and then imidization by cyclization of the ring at a high temperature. Usually, pyromellitic dianhydride (PMDA) or biphenyltetracarboxylic dianhydride (BPDA) or the like is used as an aromatic dianhydride component in order to prepare a polyimide resin, and oxydianiline (ODA) is used as an aromatic diamine component. , p-phenylene diamine (p-PDA), m-phenylene diamine (m-PDA), methylenedianiline (MDA), bisaminophenylhexafluoropropane (HFDA) and the like are used.

These polyimide resins are insoluble and insoluble ultra high heat resistant resins, and have excellent properties such as heat oxidation resistance, heat resistance, radiation resistance, low temperature characteristics, chemical resistance, and the like, and heat-resistant advanced materials such as automobile materials, aviation materials, and spacecraft materials. It is used in a wide range of fields in electronic materials, such as insulating coatings, insulating films, semiconductors, and electrode protective films of TFT-LCDs. Recently, display materials such as optical fibers and liquid crystal alignment films and conductive fillers are contained in films or coated on surfaces to be used for transparent electrode films. have.

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, which makes 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. 5986036 and 6232428 and Korean Patent Laid-Open Publication No. 2003-0009437 disclose monomers having a backbone structure connected to a linking group such as -O-, -SO ₂ -, or CH ₂ - and the like at an m-position other than the p-position There has been reported a novel structure of polyimide having improved transparency and color transparency as far as the thermal property is not significantly deteriorated by using aromatic dianhydride dianhydride and aromatic diamine monomer having a substituent such as -CF ₃ , Mechanical properties, yellowing degree and visible light transmittance are not enough to be used as a substrate for a semiconductor insulating film, a TFT-LCD insulating film, an electrode protecting film, and a flexible display.

Accordingly, the present invention is to provide a polyimide resin having a colorless transparent and excellent mechanical properties and thermal stability properties, and a liquid crystal alignment film and a film using the same.

In a preferred embodiment of the invention, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (FDA) and 3,4,3 ', 4'-biphenyl as aromatic dianhydrides Provided is a polyimide resin containing tetracarboxylic dianhydride (BPDA), containing a fluorine-containing diamine as an aromatic diamine, and having a yellowing degree of 10 or less based on a thickness of 50 to 100 μm when forming a film or film.

The polyimide resin according to the embodiment may further include a dianhydride having a soft group represented by Formula 1 as an aromatic dianhydride.

≪ Formula 1 >

는

,

및

중 선택된 구조이다.In this formula,

The

,

And

Among the structures selected.

When the polyimide resin according to the embodiment is 100 mol% of the total dianhydride component, the polyimide resin may include 15 to 35 mol% of dianhydride having a flexible group represented by Chemical Formula 1.

The polyimide resin according to the above embodiment is bis (3-aminophenyl) sulfone (3-DDS), bis (4-aminophenyl) sulfone (4-DDS), 1,3-bis (3-aminophenoxy) as an aromatic diamine. Benzene (APB-133), 1,3-bis (4-aminophenoxy) benzene (APB-134), 1,4-bis (4-aminophenoxy) benzene (APB-144) and 4,4 It may further include a single or two or more compounds selected from -bis (3-aminophenoxy) diphenylsulfone (DBSDA).

The polyimide resin according to the embodiment is 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB), 3,3'-bis as fluorine-containing diamine. (Trifluoromethyl) -4,4'-diaminobiphenyl (3,3'-TFDB), 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (DBOH), 2 , 2'-bis [4 (4-aminophenoxy) phenyl] hexafluoropropane (4-BDAF), 2,2'-bis [3 (3-aminophenoxy) phenyl] hexafluoropropane (3- BDAF), 2,2'-bis (3-aminophenyl) hexafluoropropane (3,3'-6F) and 2,2'-bis (4-aminophenyl) hexafluoropropane (4,4'- 6F) may be included alone or two or more compounds selected.

In the polyimide resin according to the embodiment, when the total diamine component is 100 mol%, the fluorine-containing diamine may be 50 mol% or more.

In another preferred embodiment of the present invention, a liquid crystal alignment film including the polyimide resin is provided.

Another preferred embodiment of the present invention includes a polyimide resin, and provides a polyimide film having a transmittance of 87% or more at 550 nm based on a film thickness of 50 to 100 μm.

In the polyimide film according to the embodiment, the average linear expansion coefficient (CTE) at 50 to 200 ° C. and 50 to 250 ° C. may be 50 ppm / ° C. or less, and more preferably 30 ppm / ° C. or less.

The polyimide film according to the embodiment may have a dielectric constant of 3.0 or less at 1 GHz.

As described above, the present invention is colorless and transparent, and has excellent mechanical and thermal stability properties such as semiconductor insulating film, TFT-LCD insulating film, passivation film, liquid crystal alignment film, optical communication material, solar cell protective film, flexible display substrate, etc. A polyimide resin usable in various fields and a liquid crystal alignment film and a film using the same can be provided.

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

The polyimide resin of the present invention is formed of a polyimide obtained by imidizing a polyamic acid synthesized from aromatic diamine and aromatic dianhydride as a main raw material, and is colorless and transparent. In particular, in order to use the polyimide resin of the present invention as an electronic material requiring transparency, it is preferable that the yellowing degree is 10 or less based on a thickness of 50 to 100 μm when forming a film or a film.

Aromatic dianhydrides used for this purpose are 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (FDA) and 3,4,3 ', 4'-biphenyl tetracarboxylic Dianhydride (BPDA) essentially. The content is not particularly limited, but the molar ratio of FDA and BPDA is preferably 4: 1 to 1: 2.

In addition to the aromatic dianhydride may further include a dianhydride having a soft group represented by the following formula (1).

≪ Formula 1 >

는

,

및

중 선택된 구조이다.In this formula,

The

,

And

Among the structures selected.

At this time, the content of the dianhydride having a flexible group represented by the formula (1) is not particularly limited, but when the total dianhydride component is 100 mol%, it is preferably 15 to 35 mol%.

The aromatic diamine is preferably one containing a fluorine-containing diamine. Specifically, for example, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB ), 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (3,3'-TFDB), 2,2-bis (3-amino-4-hydroxyphenyl) hexa Fluoropropane (DBOH), 2,2'-bis [4 (4-aminophenoxy) phenyl] hexafluoropropane (4-BDAF), 2,2'-bis [3 (3-aminophenoxy) phenyl ] Hexafluoropropane (3-BDAF), 2,2'-bis (3-aminophenyl) hexafluoropropane (3,3'-6F) and 2,2'-bis (4-aminophenyl) hexafluoro Single or 2 or more types of compounds selected from the loafrovane (4,4'-6F) are mentioned.

Furthermore, bis (3-aminophenyl) sulfone (3-DDS), bis (4-aminophenyl) sulfone (4-DDS), 1,3-bis (3-aminophenoxy) benzene (APB-133) as aromatic diamine ), 1,3-bis (4-amino phenoxy) benzene (APB-134), 1,4-bis (4-aminophenoxy) benzene (APB-144) and 4,4-bis (3-aminophenoxy C) diphenylsulfone (DBSDA) may further comprise a single or two or more compounds selected.

In this case, the content of the fluorine-containing diamine is not particularly limited, but when the total diamine component is 100 mol%, it is preferable to contain 50 mol% or more of the fluorine-containing diamine.

The polyimide film of this invention can also contain components other than the diamine and dianhydride demonstrated above, The content is not specifically limited.

This can have a high transmittance and transparency, it is possible to maintain the excellent electrical, thermal and mechanical properties of the polyimide.

The dianhydride component and the diamine component described above are dissolved in an organic solvent in an equimolar amount to react to prepare a polyamic acid solution.

The reaction conditions are not particularly limited, but the reaction temperature is preferably -20 to 80 占 폚, and the reaction time is preferably 2 to 48 hours. It is more preferable that the reaction atmosphere is an inert atmosphere such as argon or nitrogen.

The organic solvent for the solution polymerization of the monomers described above is not particularly limited as long as it is a solvent in which the polyamic acid is dissolved. As the known reaction solvent, there may be used, for example, m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO) One or more polar solvents are used. In addition, a low boiling point solution such as tetrahydrofuran (THF), chloroform or a low-absorbency solvent such as? -Butyrolactone may be used.

The content of the organic solvent is not particularly limited, but in order to obtain an appropriate molecular weight and viscosity of the polyamic acid solution, the content of the organic solvent is preferably 50 to 95% by weight of the total polyamic acid solution, and more preferably 70 to 90% by weight. It is more preferable that is.

The polyimide resin prepared by imidating the polyamic acid solution thus prepared is preferably a glass transition temperature of 200 ~ 350 ℃.

When using polyamic acid prepared by the above monomers as a liquid crystal alignment film, spin coating or roll coating on a glass substrate (usually ITO Glass), followed by 80 ° C./5 minutes, 250 ° C./20 minutes thermal curing process. Simultaneously with removal, polyimide is formed to form a thin film (usually about 100 ~ 1000 nm) on the glass substrate. At this time, the polyamic acid solution prepared for the improvement of coating property, surface flatness, etc. Dilute to a viscosity of 10 ~ 50cps, where the solvent used for dilution is not limited to the solvent used for polymerization. Known diluents include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), or γ-butyrolactone, 2-n-butoxyethanol, and the like. One or more polar solvents selected from these may be used alone or in combination, but is not limited thereto.

In addition, when using the polyamic acid prepared by the monomers as the liquid crystal alignment layer, the coating solution may be prepared according to one or more methods selected from the following manufacturing methods, but is not limited thereto.

1. Using polyamic acid solution

2. The polymerized polyamic acid is polyimidized by heat and / or chemical curing, then resinized using precipitation method, dissolved in organic solvent, and then converted into a solution (ie, coating solution).

3. Use polyamic acid polymerized as 2. in polyimide through thermal and / or chemical curing and then as a coating solution (without resination).

4. Mix the solution in the form of 1. and 2. or 3. and use it as coating liquid.

5. Add (dissolve) the resin prepared by the method of 2. to the polyamic acid solution of 1.

In addition, the coating liquids prepared by the above method may be used through two or more stages of filtration using a particle and ion filter selected in the range having a pore size of 0.1 to 5 μm immediately before the coating process.

In addition, when manufacturing a polyimide film using a polyamic acid solution, fillers may be added to the polyamic acid solution for the purpose of improving various properties such as the sliding property, thermal conductivity, conductivity, and corona resistance of the polyimide film. Although it does not specifically limit as a filler, As a preferable specific example, a silica, titanium oxide, layered silica, carbon nanotube, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, etc. are mentioned.

The particle diameter of the filler may vary depending on the characteristics of the film to be modified and the type of filler to be added, but is not particularly limited, but in general, the average particle diameter is preferably 0.001-50 μm, and preferably 0.005-25 μm. It is more preferable, More preferably, it is good that it is 0.01-10 micrometers. In this case, the modification effect of a polyimide film tends to appear, and favorable surface property, electroconductivity, and a mechanical characteristic can be acquired in a polyimide film.

Moreover, it does not specifically limit as it can fluctuate also with the film characteristic to be modified, filler particle diameter, etc. about the addition amount of the said filler. Generally, it is preferable that the addition amount of a filler is 0.001-20 weight part with respect to 100 weight part of polyamic-acid solutions, More preferably, it is 0.01-10 weight part.

The addition method of a filler is not specifically limited, For example, the method of adding to a polyamic-acid solution before superposition | polymerization or after superposition | polymerization, the method of kneading a filler using 3 rolls etc. after completion | finish of polyamic acid polymerization, the dispersion liquid containing filler The method of preparing and mixing this into a polyamic-acid solution, etc. are mentioned.

The method of manufacturing a polyimide film from the obtained polyamic-acid solution is not specifically limited, A conventionally well-known method can be used. As a method of imidating a polyamic-acid solution, a thermal imidation method and a chemical imidation method are mentioned, It is more preferable to use a chemical imidation method. The chemical imidization method is a method of applying an imidization catalyst represented by a dehydrating agent represented by acid anhydrides such as acetic anhydride and tertiary amines such as isoquinoline, β-picolin and pyridine to the polyamic acid solution. The thermal imidation method may be used in combination with the chemical imidization method, and the heating conditions may vary depending on the type of the polyamic acid solution, the thickness of the film, and the like.

The polyamic acid solution was heated at 80-200 ° C. on the support, preferably 100-180 ° C. to activate the dehydrating agent and the imidization catalyst, thereby partially curing and drying the polyamic acid film in a gel state to obtain a peeled from the support, and the gel The film of a state is heated at 200-400 degreeC for 5 to 400 second, and a polyimide film is obtained.

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

The polyimide film produced in the present invention has an average linear expansion coefficient (CTE) of 50 ppm / ° C or less at 50 to 250 ° C and an average linear expansion coefficient (CTE) of 50 ppm / ° C or less in consideration of dimensional stability. When the polyimide film is used in the TFT ARRAY process when the film exceeds 50 ppm / ° C, the electrode doping process is performed because the film shrinks and expands according to the process temperature. There is a problem that the alignment (Alignment) is not matched, and the film does not maintain the horizontal (flattening), so that warpage occurs. Therefore, the smaller the CTE value, the more precise TFT processing is possible.

In addition, the polyimide film of the present invention preferably has a transmittance of 87% or more at 550 nm based on a thickness of 50 to 100 μm, and as mentioned above, the polyimide resin of the present invention has a thickness of 50 to 100 when forming a film or a film. It is preferable that yellowing degree is 10 or less on a micrometer basis.

The polyimide resins and films of the present invention satisfying the above-mentioned transmittance and yellowing degree are interlayers in diffusion plates and coating films in protective films or TFT-LCDs, such as TFT-LCDs, which have been limited in use due to the yellow color of existing polyimide films. , Gate Insulator and liquid crystal alignment film, etc. can be used in the field where transparency is required, and when the transparent polyimide is applied to the liquid crystal alignment film, it contributes to the increase of the aperture ratio and enables the production of high-contrast TFT-LCD. In addition, it can be used for a flexible display substrate.

 In addition, the polyimide film of the present invention preferably has a dielectric constant of 3.0 or less at 1 GHz, which makes it possible to use a passivation film in a semiconductor.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

≪ Example 1 >

The reactor was filled with 577.49 g of N, N-dimethylacetamide (DMAc) while passing nitrogen through a 1000 ml 3-Neck round bottom flask equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a cooler. After the temperature was lowered to 0 ° C., 2,2′-TFDB (0.20 mol) was dissolved to maintain this solution at 0 ° C. 8.83 g (0.03 mol) of BPDA was added thereto to completely dissolve it, and then 9.31 g (0.03 mol) of ODPA was added thereto, followed by addition of 62.19 g (0.14 mol) of 6-FDA, followed by stirring to completely dissolve it. At this time, the solid content was 20 wt%, and then the solution was left at room temperature and stirred for 8 hours. At this time, the solution viscosity at 23 degreeC was obtained the polyamic-acid solution of 2500poise.

After completion of the reaction, the polyamic acid solution obtained was cast to a thickness of 50㎛ ~ 100㎛ by using a doctor blade on a glass plate and dried in a vacuum oven for 1 hour at 40 ℃, 2 hours at 60 ℃ to obtain a self standing film A polyimide film having a thickness of 50 μm and 100 μm was obtained by heating at 80 ° C. for 3 hours at 100 ° C., 1 hour at 100 ° C., 1 hour at 200 ° C., and 30 minutes at 300 ° C. in a high temperature furnace oven.

≪ Examples 2 to 3 >

A polyimide film was obtained in the same manner as in Example 1, except that the dianhydride content was added in the molar ratio of Table 1 below.

<Example 4>

In Example 1, 2,2′-TFDB 57.64 g (0.18 mol) was dissolved in 581.82 g of N, N-dimethylacetaamide (DMAc), and 4.97 g (0.02 mol) of 3-DDS was added to completely dissolve it. . 11.77 g (0.04 mol) of BPDA was added thereto to completely dissolve it, and then 71.08 g (0.16 mol) of 6-FDA was added and stirred to dissolve completely. At this time, the solid content was 20 wt%, and then the solution was left at room temperature and stirred for 8 hours. At this time, the solution viscosity at 23 degreeC was obtained the polyamic-acid solution of 2200 poise.

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

<Examples 5-7>

A polyimide film was obtained in the same manner as in Example 4, except that the dianhydride and diamine contents were added in the molar ratios of Table 1 below.

&Lt; Example 8 >

A polyimide film was obtained in the same manner as in Example 4, except that 4-DDS was used instead of 3-DDS, which is dianhydride.

<Examples 9-11>

A polyimide film was obtained in the same manner as in Example 8, except that the dianhydride and diamine contents were added in the molar ratios of Table 1 below.

&Lt; Comparative Example 1 &

In Example 1, 103.69 g (0.20 mol) of 4-BDAF was dissolved in 769.80 g of N, N-dimethylacetaamide (DMAc), and 88.85 g (0.20 mol) of 6-FDA was added thereto, followed by stirring for 1 hour. 6-FDA was completely dissolved. At this time, the solid content was 20 wt%, and then the solution was left at room temperature and stirred for 8 hours. At this time, the solution viscosity at 23 degreeC was obtained the polyamic-acid solution of 1300 poise.

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

<Comparative Example 2-4>

A polyimide film was obtained in the same manner except that the kind and content of dianhydride and diamine in Comparative Example 1 were added in the molar ratio of Table 1 below.

The physical properties of the polyimide films prepared in Examples and Comparative Examples were measured as follows and are shown in Table 1 below.

(1) transmittance

The film prepared in Example was measured for transmittance at 550 nm by using a UV spectrometer (Varian, Cary 100).

(2) yellowing degree

Yellowing degree was measured by ASTM E313 standard.

(3) Modulus of elasticity

The measurement was performed according to JIS K 6301 using Instron's Universal Testing Machine Model 1000.

(4) Glass transition temperature (Tg)

The glass transition temperature was measured using a differential scanning calorimeter (DSC, TA Instrument, Q200).

(5) coefficient of linear expansion (CTE)

The coefficient of linear expansion at 50-200 ° C and 50-250 ° C was measured according to TMA-Method using TMA (TA Instrument, Q400).

(6) permittivity

The dielectric constant at 1 GHz was measured according to ASTM D-150 standard.

As a result of the physical property evaluation, the polyimide film prepared according to the embodiment of the present invention had a yellowing degree of 10 or less despite a thickness of 100 μm, and the polyimide film of the present invention was excellent in transmittance at 550 nm, which is a visible light region. It turns out that this colorless transparency is excellent.

In addition, the average linear expansion coefficient of 50ppm / ℃ or less does not lower the dimensional stability is excellent thermal stability, it can be seen that it can be applied to the TFT process for the production of substrate materials, such as flexible display and active-driven display device.

On the other hand, in the case of the comparative example, yellowing degree was high, and in the case of Comparative Example 4 in particular, it was impossible to form a film with a thickness of 90 μm or more.

Claims (11)

As aromatic dianhydrides 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (FDA) and 3,4,3 ', 4'-biphenyl tetracarboxylic dianhydride ( BPDA) and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB), 3,3'-bis (trifluoro) as aromatic diamine Single or two selected from methyl) -4,4′-diaminobiphenyl (3,3′-TFDB) and 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (DBOH) Polyimide resin containing at least a fluorine-containing diamine, yellowing degree of 10 or less on the basis of 50 ~ 100㎛ thickness when forming a film or film. The method of claim 1, A polyimide resin further comprising a dianhydride having a soft group represented by the following general formula (1) as an aromatic dianhydride. &Lt; Formula 1 >

In this formula,

The

,

And

Among the structures selected. The method of claim 2, When the total dianhydride component is 100 mol%, polyimide resin comprising 15 to 35 mol% of dianhydride having a flexible group represented by the formula (1). The method of claim 1, Bis (3-aminophenyl) sulfone (3-DDS), bis (4-aminophenyl) sulfone (4-DDS), 1,3-bis (3-aminophenoxy) benzene (APB-133) as aromatic diamine, 1,3-bis (4-aminophenoxy) benzene (APB-134), 1,4-bis (4-aminophenoxy) benzene (APB-144) and 4,4-bis (3-aminophenoxy) A polyimide resin further comprising a single or two or more compounds selected from diphenylsulfone (DBSDA). delete The method of claim 1, When the total diamine component is 100 mol%, the fluorine-containing diamine contains at least 50 mol% polyimide resin characterized in that. The liquid crystal aligning film containing the polyimide resin of any one of Claims 1-4. A polyimide film comprising the polyimide resin of any one of claims 1 to 4 and 6 and having a transmittance of 87% or more at 550 nm based on a film thickness of 50 to 100 µm. 9. The method of claim 8, The average linear expansion coefficient (CTE) in 50-200 degreeC and 50-250 degreeC is 50 ppm / degrees C or less, The polyimide film characterized by the above-mentioned. The method of claim 9, The average linear expansion coefficient (CTE) in 50-200 degreeC and 50-250 degreeC is 30 ppm / degrees C or less, The polyimide film characterized by the above-mentioned. 9. The method of claim 8, A polyimide film having a dielectric constant of 1 or less at 3.0 GHz.