KR20140118386A - Polyimide resin and film thereof - Google Patents

Abstract

The present invention relates to a polyimide resin and a polyimide film using the same. Provided are a polyimide resin and a polyimide film which are colorless and transparent and have an excellent thermal expansion coefficient and low birefringence properties by including repeating units derived from a diamine-based monomer and a dianhydride-based monomer, and including 1,4-diaminocyclohexane (TCHD) and bistrifluoromethylbenzylamines (TFDB) for the diamine-based monomer.

Description

TECHNICAL FIELD The present invention relates to a polyimide resin and a polyimide film using the same,

The present invention relates to a polyimide resin and a polyimide film using the same.

In general, a polyimide (PI) film is a film made of a polyimide resin, and a polyimide resin is produced by solution polymerization of an aromatic dianhydride and an aromatic diamine or aromatic diisocyanate to prepare a polyamic acid derivative, Refers to a high heat-resistant resin produced by imidization. (PMDA) or biphenyltetracarboxylic acid dianhydride (BPDA) or the like is used as an aromatic dianhydride component, and examples of the aromatic diamine component include oxydianiline (ODA), p (P-PDA), m-phenylenediamine (m-PDA), methylene dianiline (MDA), and bisaminophenylhexafluoropropane (HFDA).

Such a polyimide resin is an insoluble and non-fusible ultra high heat resistant resin, and has excellent heat resistant oxidizing property, heat resistance property, radiation resistance property, low temperature property, chemical resistance, etc. and is excellent in heat resistant materials such as automobile materials, Insulating coatings, semiconductors, and electrode protection films for TFT-LCDs.

However, since the polyimide resin is colored with brown and yellow due to high aromatic ring density, it has low transmittance in the visible light region, has a yellowish color and low light transmittance, and has a large birefringence, There are difficulties.

In order to solve this problem, conventionally, a method of purifying monomers and a solvent and polymerizing them has been attempted, but the improvement of the transmittance has not been remarkable.

In addition, U.S. Patent No. 5053480 discloses a method of using an aliphatic cyclic dianhydride component instead of an aromatic dianhydride. Compared with the purification method, there is an improvement in transparency and color when it is made into a solution or a film, And thus the high transmittance was not satisfied and the thermal and mechanical properties were deteriorated.

Also, U.S. Patent Nos. 4595548, 4603061, 4645824, 4895972, 5218083, 5093453, 5218077, 5367046, 5338826. 5986036 and 6232428 and Korean Patent Laid-Open Publication No. 2003-0009437 disclose that a monomer having a bridged structure connecting to a linking group such as -O-, -SO ₂ -, or CH ₂ - and the like at an m- , Or a novel structure of polyimide with improved transparency and color transparency as long as the thermal properties are not significantly deteriorated by using an aromatic dianhydride dianhydride having a substituent such as -CF ₃ and an aromatic diamine monomer However, the birefringence characteristics were insufficient.

Therefore, a colorless transparent polyimide film is required to have a low thermal expansion coefficient and low birefringence characteristics for securing a viewing angle in order to be applied to various display materials fields.

The main object of the present invention is to provide a colorless transparent polyimide resin having excellent thermal expansion coefficient and low birefringence characteristics and a polyimide film using the same.

The present invention also provides a substrate for an image display device comprising the polyimide film.

In order to achieve the above-mentioned object, one embodiment of the present invention is a polymer electrolyte membrane comprising a repeating unit derived from a diamine-based monomer and a dianhydride-based monomer, wherein the diamine-based monomer is 1,4-diaminocyclohexane (TCHD) And bis (trifluoromethyl) benzidine (TFDB).

In one preferred embodiment of the present invention, the 1,4-diaminocyclohexane (TCHD) is contained in an amount of 10 to 40 mol% based on the total diamine monomer, and the bistrifluoromethylbenzidine (TFDB) Is 60 to 90 mol% with respect to the total diamine-based monomer.

In one preferred embodiment of the present invention, the diamine-based monomer is at least one member selected from the group consisting of bisaminohydroxyphenylhexafluoropropane (DBOH), bisaminophenoxybenzene (133APB, 134APB, 144APB), bisaminophenylhexafluoropropane 6F and 44-6F), bisaminophenyl sulfone (4DDS, 3DDS), bisaminophenoxyphenylhexafluoropropane (4BDAF), bisaminophenoxyphenylpropane (6HMDA) and bisaminophenoxy diphenyl sulfone (DBSDA) And at least one compound selected from the group consisting of

In one preferred embodiment of the present invention, the dianhydride monomer is selected from the group consisting of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydride (6FDA), cyclobutane tetracarboxylic dianhydride (CBDA), biphenyl tetracarboxylic dianhydride (BPDA), bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTA), 4 - (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride (TDA), pyromellitic acid dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), biscarboxyphenyldimethylsilanediamine hydride (SiDA), oxydiphthalic dianhydride Hydride (ODPA), bisdicarboxyphenoxy diphenylsulfide dianhydride (BDSDA), sulfonyl diptal The anhydride (SO2DPA) isopropylidene and the at least one selected from the group consisting of phenoxy-bis program anhydride (6HDBA) Talic can be characterized.

In one preferred embodiment of the present invention, the dianhydride monomer is selected from the group consisting of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6FDA) and cyclobutane tetracarboxylic dianhydride (CBDA).

In one preferred embodiment of the present invention, the dianhydride monomer is selected from the group consisting of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6FDA) and cyclobutane tetracarboxylic dianhydride (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) is present in an amount of from 20 to 100 mol% based on the total dianhydride monomer, and the 2,2-bis (3,4-dicarboxyphenyl) May be characterized by containing 1 to 5 molar ratio with respect to 1 mol of the carboxylic dianhydride (CBDA).

Another embodiment of the present invention provides a polyimide film comprising the polyimide resin.

In another preferred embodiment of the present invention, the birefringence is 0.008 or less.

In another preferred embodiment of the present invention, R _o (planar phase difference) is 1 nm or less and R _th (thickness direction retardation) is 100 nm or less (thickness is 10 to 12 μm).

In another preferred embodiment of the present invention, when the transmittance is measured by a UV spectrometer based on a film thickness of 10 to 12 μm, the transmittance at 550 nm is 88% or more.

In another preferred embodiment of the present invention, the thermal expansion coefficient (CTE) at 50 to 300 DEG C is 40 ppm / DEG C or less.

Another embodiment of the present invention provides a substrate for an image display device comprising the polyimide film.

According to the present invention, it is possible to provide a polyimide resin and a film which are colorless and transparent and have an excellent thermal expansion coefficient and a low birefringence characteristic, and can be used as a semiconductor insulating film, a TFT-LCD insulating film, a passivation film, a liquid crystal alignment film, There is an effect that the present invention can be applied to various fields in which thermal stability is required along with excellent optical characteristics such as substrates for image display devices.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

In one aspect of the present invention, there is provided a process for producing a polymer comprising repeating units derived from a diamine-based monomer and a dianhydride-based monomer, wherein the diamine-based monomer is 1,4-diaminocyclohexane (TCHD) and bistrifluoromethylbenzidine ). ≪ / RTI >

In another aspect, the present invention relates to a polyimide film comprising the polyimide resin.

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

Disclosed is a polyimide resin comprising a repeating unit derived from a diamine-based monomer and a dianhydride-based monomer. The polyimide resin is obtained by reacting 1,4-diamino (TCHD), and bistrifluoromethylbenzidine (TFDB). ≪ Desc / Clms Page number 2 >

The 1,4-diaminocyclohexane (TCHD) has a cyclohexane group and has a lower birefringence value than other diamine monomers having a benzene ring. On the other hand, bistrifluoromethylbenzidine (TFDB) can improve the thermal expansion coefficient. When 1,4-diaminocyclohexane (TCHD) and bistrifluoromethylbenzidine (TFDB) are used together, A polyimide resin and a film having a low birefringence value can be produced while improving the thermal expansion coefficient while maintaining optical properties.

When the content of the 1,4-diaminocyclohexane (TCHD) is 10-40 mol% based on the total diamine-based monomer and the content of the 1,4-diaminocyclohexane (TCHD) is less than 10 mol% based on the total diamine-based monomer, When the content is more than the mol%, a low molecular weight may cause a problem that flexibility of the film is deteriorated.

In the case where the content of bistrifluoromethylbenzidine (TFDB) is 60 to 90 mol% based on the total diamine-based monomer and the content is less than 60 mol% based on the total diamine-based monomer, The birefringence value of the film may be increased.

In the present invention, other diamine-based monomers other than 1,4-diaminocyclohexane (TCHD) and bistrifluoromethylbenzidine (TFDB) may be used as the diamine-based monomer, and examples thereof include bisaminohydroxyphenylhexa- (33D), bisaminophenoxybenzene (133APB, 134APB, 144APB), bisaminophenylhexafluoropropane (33-6F, 44-6F), bisaminophenyl sulfone (4DDS, 3DDS), bisaminophenoxy But is not limited to, at least one selected from the group consisting of cyphenylhexafluoropropane (4BDAF), bisaminophenoxyphenylpropane (6HMDA), and bisaminophenoxy diphenylsulfone (DBSDA).

The dianhydride monomer used in the present invention is not particularly limited, but may be 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), cyclobutane tetracarboxylic (CBDA), biphenyl tetracarboxylic dianhydride (BPDA), bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTA ), 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride (TDA), pyromellitic acid Dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), biscarboxyphenyldimethylsilanediamine hydride (SiDA), oxy Diphthalic dianhydride (ODPA), bisdicarboxyphenoxy diphenylsulfide dianhydride (BDSD A), sulfonyldiphthalic anhydride (SO2DPA), and isopropylidene may be at least one selected from the group consisting of phenoxy bisphthalic anhydride (6HDBA).

In addition, the dianhydride monomer of the present invention can be preferably used in combination with 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and cyclobutane tetra It is preferably a carboxylic dianhydride (CBDA). The fluoro system of the 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydride (6FDA) can realize a low thermal expansion coefficient, and the cyclobutane tetracarboxylic dianhydride (CBDA) Can realize a low birefringence value of the polyimide resin due to the cyclobutane structure.

If 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6FDA) and cyclobutane tetracarboxylic dianhydride (CBDA) are used as the dianhydride monomer, It is preferable that the content is 20 to 100 mol% with respect to the total dianhydride monomer in terms of the thermal expansion coefficient and the birefringence value, more preferably 60 to 90 mol%.

The above 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydride (6FDA) is used in an amount of 1 to 5 mol per 1 mol of the cyclobutanetetracarboxylic dianhydride (CBDA) Are desirable for achieving thermal stability and low birefringence values.

The polyamic acid solution can be prepared by polymerizing the above-mentioned dianhydride monomer and diamine monomer in a 1: 1 equivalent ratio at a reaction temperature of -10 to 80 ° C and a reaction time of 1 to 48 hours in a nitrogen or argon atmosphere .

The solvent (polymerization solvent) for the polymerization reaction of the above monomers is not particularly limited as long as it is a solvent dissolving the polyamic acid. 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. In addition, a low boiling point solution such as tetrahydrofuran (THF), chloroform or a low-absorbency solvent such as? -Butyrolactone may be used.

Although the content of the solvent is not particularly limited, the content of the solvent for the polymerization (first solvent) in the polyamic acid solution is preferably 50 to 95% by weight, more preferably, And more preferably 70 to 90% by weight.

The polyimide resin prepared by imidizing the polyamic acid solution thus prepared preferably has a glass transition temperature (Tg) of 200 to 400 ° C in consideration of thermal stability.

In the method of producing a polyimide film according to the present invention, in the step of casting and polymerizing a polymerized polyamic acid in a support, imidation methods to be applied include a thermal imidation method, a chemical imidation method, The chemical imidation method can be used in combination.

The thermal imidation method is a method in which a polyamic acid solution is cast on a support, and the polyimide film is obtained by heating the solution for 1 to 8 hours while gradually heating the solution in a temperature range of 40 to 400 ° C.

In the chemical imidation method, a dehydrating agent represented by an acid anhydride such as acetic anhydride and a imidation catalyst represented by tertiary amines such as isoquinoline, β-picoline, and pyridine are added to the polyamic acid solution. When the thermal imidation method or the thermal imidization method is used in combination with the chemical imidation method, the heating conditions of the polyamic acid solution may be varied depending on the type of the polyamic acid solution, the thickness of the polyimide film to be produced, and the like.

More specifically, a polyimide film production example in which the thermal imidation method and the chemical imidization method are used in combination is described. More specifically, a polyimamic acid solution is loaded with a dehydrating agent and an imidation catalyst, cast on a support, Preferably at 100 to 180 ° C to activate the dehydrating agent and the imidization catalyst to partially cure and dry the polyimide film, and then heat at 200 to 400 ° C for 5 to 400 seconds to obtain a polyimide film.

In the present invention, a polyimide film may be prepared from the polyamic acid solution as follows. Namely, after the obtained polyamic acid solution is imidized, the imidized solution is put into a second solvent, followed by precipitation, filtration and drying to obtain a solid content of the polyimide resin, and the solid content of the obtained polyimide resin is added to the first solvent Can be obtained through a film-forming process using a dissolved polyimide solution.

The first solvent may be the same solvent as that used in the polymerization of the polyamic acid solution. The second solvent may be one having a lower polarity than the first solvent in order to obtain the solid content of the polyimide resin, Alcohols, ethers, and ketones. At this time, the content of the second solvent is not particularly limited, but is preferably 5 to 20% by weight based on the weight of the polyamic acid solution.

It is preferable that the polyimide resin solids obtained as described above are filtered and dried by considering the boiling point of the second solvent at a temperature of 50 to 120 ° C and a time of 3 to 24 hours.

Thereafter, the polyimide solution in which the solid polyimide resin is dissolved is cast on a support, and heated at a temperature in the range of 40 to 400 ° C for 1 minute to 8 hours while gradually heating the polyimide solution to obtain a polyimide film.

The thickness of the polyimide film obtained by the above-described method is not particularly limited, but is preferably in the range of 10 to 250 mu m, more preferably 10 to 150 mu m.

The polyimide film obtained by the method described above has a transmittance of at least 88% at 550 nm and a thermal expansion coefficient (CTE) at 50 to 300 캜 of 40 ppm / ° C .; the birefringence is 0.008 or less; R _o (plane direction retardation) is 1 nm or less; and R _th (thickness direction retardation) is 100 nm or less (thickness 10 to 12 μm).

In another aspect, the present invention relates to a substrate for an image display device comprising the polyimide film.

The substrate for an image display device according to the present invention has a high heat-resistant colorless and transparent polyimide film having an excellent thermal expansion coefficient and a low birefringence characteristic, so that it can be advantageous in a high-temperature process and securing a viewing angle.

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>

N, N-dimethylacetamide (DMAc) was charged in a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser while nitrogen was passed through the reactor, the temperature of the reactor was adjusted to 60 ° C, 3.43 g (0.03 mol) of TCHD and 38.43 g (0.12 mol) of TFDB were dissolved and the solution was cooled to 25 캜. 53.31 g (0.12 mol) of 6FDA and 5.88 g (0.03 mol) of CBDA were added and reacted at 25 ° C for 1 hour to obtain a polyamic acid solution having a solid content of 15% by weight and a viscosity of 475 poise.

After the reaction was completed, the obtained solution was applied to a stainless steel plate, cast to 90 μm, dried with hot air at 150 ° C. for 1 hour, 200 ° C. for 1 hour and 300 ° C. for 30 minutes with hot air, 12 占 퐉 polyimide film was obtained.

< Example  2>

Nitrogen was passed through a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser, and 530.4 g of N, N-dimethylacetamide (DMAc) was charged. The temperature of the reactor was adjusted to 60 ° C, 3.43 g (0.03 mol) of TFDB and 38.43 g (0.12 mol) of TFDB were dissolved and the solution was cooled to 25 캜. 39.98g (0.09mol) of 6FDA and 11.77g (0.06mol) of CBDA were added and reacted at 25 ° C for 12 hours to obtain a polyamic acid solution having a solid content of 15 wt% and a viscosity of 502 poise.

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

< Example  3>

N, N-dimethylacetamide (DMAc) was charged into a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser while passing nitrogen through the reactor, the temperature of the reactor was adjusted to 60 ° C, 3.43 g (0.03 mol) of TCHD and 38.43 g (0.12 mol) of TFDB were dissolved and the solution was cooled to 25 캜. After adding 39.98g (0.09mol) of 6FDA, 8.83g (0.045mol) of CBDA and 3.27g (0.015mol) of PMDA, the mixture was reacted at 25 ° C for 12 hours to obtain a solution having a solid content of 15% by weight and a viscosity of 582 poise A polyamic acid solution was obtained.

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

< Example  4>

Nitrogen was passed through a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser, and 514.5 g of N, N-dimethylacetamide (DMAc) was charged. The temperature of the reactor was adjusted to 60 ° C, 3.43 g (0.03 mol) of TFDB and 38.43 g (0.12 mol) of TFDB were dissolved and the solution was cooled to 25 캜. After adding 33.32g (0.075mol) of 6FDA, 11.77g (0.06mol) of CBDA and 3.27g (0.015mol) of PMDA and reacting at 25 ° C for 12 hours, the solid content was 15% by weight and the viscosity was 496 poise A polyamic acid solution was obtained.

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

< Example  5>

N, N-dimethylacetamide (DMAc) 555.9 g was charged into a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser while nitrogen was passed through the reactor, the temperature of the reactor was adjusted to 60 ° C, 3.43 g (0.03 mol) of TFDB and 38.43 g (0.12 mol) of TFDB were dissolved and the solution was cooled to 25 캜. After adding 39.98g (0.09mol) of 6FDA, 5.88g (0.03mol) of CBDA and 8.83g (0.03mol) of BPDA, the mixture was reacted at 25 ° C for 12 hours to obtain a solution having a solid content of 15% by weight and a viscosity of 528 poise A polyamic acid solution was obtained.

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

< Comparative Example  1>

As a reactor, 447.31 g of N, N-dimethylacetamide (DMAc) was charged while passing nitrogen through a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser. (0.15 mol) of TFDB were dissolved. 66.64 g (0.15 mol) of 6FDA was added thereto and reacted at 25 ° C for 12 hours to obtain a polyamic acid solution having a solid content of 15 wt% and a viscosity of 512 poise.

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

< Comparative Example  2>

N, N-dimethylacetamide (DMAc) (624.30 g) was charged into a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser, and the temperature of the reactor was adjusted to 25 ° C 53.31 g (0.12 mol) of 6FDA and 8.83 g (0.03 mol) of BPDA were added thereto and reacted at 25 ° C for 12 hours to obtain a solution having a solid concentration of 15% by weight and a viscosity of 536 poise solution of polyamic acid was obtained.

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

< Comparative Example  3>

432.49 g of N, N-dimethylacetamide (DMAc) was charged into a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser while passing nitrogen, and the temperature of the reactor was adjusted to 60 ° C. 17.13g (0.15mol) was dissolved and the solution was cooled to 25 占 폚. 53.31 g (0.12 mol) of 6FDA and 5.88 g (0.03 mol) of CBDA were added and reacted at 25 ° C for 12 hours to obtain a polyamic acid solution having a solid content of 15 wt% and a viscosity of 574 poise.

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

< Comparative Example  4>

N, N-dimethylacetamide (DMAc) (607.62 g) was charged into a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser while nitrogen was passed through the reactor. (0.15 mol) was dissolved and the solution was cooled to 25 캜. 53.31 g (0.12 mol) of 6FDA and 5.88 g (0.03 mol) of CBDA were added and reacted at 25 ° C for 12 hours to obtain a polyamic acid solution having a solid content of 15% by weight and a viscosity of 496 poise.

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

< Comparative Example  5>

N, N-dimethylacetamide (DMAc) was charged with 473.6 g of N, N-dimethylacetamide (DMAc) through a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser. (0.075 mol) of TFDB and 24.02 g (0.075 mol) of TFDB were dissolved and the solution was cooled to 25 캜. 53.31 g (0.12 mol) of 6FDA and 5.88 g (0.03 mol) of CBDA were added and reacted at 25 ° C for 12 hours to obtain a polyamic acid solution having a solid content of 15% by weight and a viscosity of 420 poise.

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

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

&Lt; Property evaluation method &

(1) Measurement of permeability

The films prepared in Examples and Comparative Examples were measured for transmittance at 550 nm using a UV spectrometer (Kotika Minolta CM-3700d).

(2) Coefficient of thermal expansion (CTE) measurement

TMA (Perkin Elmer, Diamond TMA) was used to measure the thermal expansion coefficient at 50 to 300 ° C. twice in accordance with the TMA-method. The temperature was measured at a rate of 10 ° C./min and a load of 100 mN Politics.

(3) Thickness measurement

The thickness was measured with an Anritsu Electronic Micrometer and the deviation of the device was less than ± 0.5%.

(4) Birefringence measurement

The average value was measured three times at 630 nm using a birefringence analyzer (Prism Coupler, Sairon SPA4000).

(6) Retardation measurement

Retardation was measured using RETS from OTSUKA ELECTRONICS. The specimen was mounted on a sample holder in the shape of a square of 1 inch each in the horizontal and the vertical directions and fixed at 550 nm using a monochrometer. R _o (plane retardation) was measured at an incident angle of 0 ° to measure in- R _th (thickness direction retardation) was measured at an incident angle of 45 ° to measure the thickness retardation.

R _o = (n _x -n _y ) * d

_{R th = [(n y -n} z) * d + (n x -n z) * d] / 2

Here, n _x is the refractive index in the x direction, n _y is the refractive index in the y direction, n _z is the refractive index in the z direction, and d is the thickness of the polyimide film.

 division ingredient Mole ratio thickness
(탆) Permeability (%) Prism Coupler Transverse electric (TE) mode TM (transverse magnetic) mode Birefringence Example 1 TCHD + TFDB / 6FDA + CBDA 20: 80/80: 20 12 89.9 1.5574 1.5520 0.005 Example 2 TCHD + TFDB / 6FDA + CBDA 20: 80/60: 40 10 90.7 1.5576 1.5505 0.007 Example 3 TCHD + TFDB / 6FDA + CBDA + PMDA 20: 80/60: 30: 10 11 90.6 1.5601 1.5520 0.008 Example 4 TCHD + TFDB / 6FDA + CBDA + PMDA 20: 80/50: 40: 10 12 90.5 1.5638 1.5554 0.008 Example 5 TCHD + TFDB / 6FDA + CBDA + BPDA 20: 80/60: 20: 20 11 89.5 1.5710 1.5646 0.006 Comparative Example 1 TFDB / 6FDA 100/100 10 90.6 1.5611 1.5554 0.006 Comparative Example 2 TFDB / 6FDA + BPDA 100/80: 20 12 89.5 1.5645 1.5594 0.005 Comparative Example 3 TCHD / 6FDA + CBDA 100/80: 20 11 90.3 1.5590 1.5448 0.014 Comparative Example 4 TFDB / 6FDA + CBDA 100/80: 20 12 88.1 1.5510 1.5411 0.010 Comparative Example 5 TCHD + TFDB / 6FDA + CBDA 50: 50/80: 20 12 89.4 1.5564 1.5434 0.013

ingredient Mole ratio thickness
(탆) Coefficient of thermal expansion
(ppm / DEG C) Phase difference meter (RETS) R _o R _th Example 1 TCHD + TFDB / 6FDA + CBDA 20: 80/80: 20 12 39.3 0.02 57.7 Example 2 TCHD + TFDB / 6FDA + CBDA 20: 80/60: 40 10 37.4 0.24 82.0 Example 3 TCHD + TFDB / 6FDA + CBDA + PMDA 20: 80/60: 30: 10 11 39.4 0.28 97.9 Example 4 TCHD + TFDB / 6FDA + CBDA + PMDA 20: 80/50: 40: 10 12 35.1 0.19 74.8 Example 5 TCHD + TFDB / 6FDA + CBDA + BPDA 20: 80/60: 20: 20 11 30.4 0.20 95.1 Comparative Example 1 TFDB / 6FDA 100/100 10 64.1 0.17 42.9 Comparative Example 2 TFDB / 6FDA + BPDA 100/80: 20 12 30.3 0.74 186.0 Comparative Example 3 TCHD / 6FDA + CBDA 100/80: 20 11 45.2 0.82 435.2 Comparative Example 4 TFDB / 6FDA + CBDA 100/80: 20 12 42.1 0.52 223.3 Comparative Example 5 TCHD + TFDB / 6FDA + CBDA 50: 50/80: 20 12 44.1 0.02 50.4

As a result of measurement of the physical properties of the polyimide films produced in Examples 1 to 5 and Comparative Examples 1 to 5, as shown in Tables 1 and 2, bistrifluoromethylbenzidine (TFDB) and 1,4-diaminocyclohexane (TCHD) had a lower birefringence value than the case of using a diamine-based monomer having a benzene ring, and the thermal expansion coefficient was also excellent.

Further, compared with the polyimide film using bistrifluoromethylbenzidine (TFDB) or 1,4-diaminocyclohexane (TCHD) alone as in Comparative Examples 1 to 4, the ratio of bistrifluoromethylbenzidine (TFDB) and It was found that the polyimide film using 1,4-diaminocyclohexane (TCHD) had a low birefringence and a thermal expansion coefficient while maintaining the light transmittance.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (12)

And a repeating unit derived from a diamine-based monomer and a dianhydride-based monomer, and the diamine-based monomer includes 1,4-diaminocyclohexane (TCHD) and bistrifluoromethylbenzidine (TFDB) By weight.
[3] The method according to claim 1, wherein the content of the 1,4-diaminocyclohexane (TCHD) is 10 to 40 mol% based on the total diamine monomer, and the content of the bistrifluoromethylbenzidine (TFDB) Based on the weight of the polyimide resin.
The method according to claim 1, wherein the diamine-based monomer is at least one selected from the group consisting of bisaminohydroxyphenylhexafluoropropane (DBOH), bisaminophenoxybenzene (133APB, 134APB, 144APB), bisaminophenylhexafluoropropane 6F), bisaminophenyl sulfone (4DDS, 3DDS), bisaminophenoxyphenylhexafluoropropane (4BDAF), bisaminophenoxyphenylpropane (6HMDA) and bisaminophenoxy diphenylsulfone (DBSDA) Wherein the polyimide resin further comprises at least one selected from the group consisting of polyimide resin and polyimide resin.
The method of claim 1, wherein the dianhydride monomer is selected from the group consisting of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6FDA), cyclobutane tetracarboxylic dianhydride (CBDA) , Biphenyl tetracarboxylic dianhydride (BPDA), bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTA), 4- , 5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride (TDA), pyromellitic acid dianhydride (Meth) acrylate, 2,4,5-benzene tetracarboxylic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), biscarboxyphenyldimethylsilanediamine hydride (SiDA), oxydiphthalic dianhydride ODPA), bisdicarboxyphenoxy diphenylsulfide dianhydride (BDSDA), sulfonyldiphthalic anhydride (SO2D PA) and isopropylidene are at least one selected from the group consisting of phenoxy bis-phthalic anhydride (6HDBA).
The method of claim 1, wherein the dianhydride monomer is selected from the group consisting of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6FDA) and cyclobutane tetracarboxylic dianhydride (CBDA) And a polyimide resin.
The method of claim 4, wherein the dianhydride monomer is selected from the group consisting of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6FDA) and cyclobutane tetracarboxylic dianhydride (CBDA) (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) is present in an amount of from 20 to 100 mol% based on the total dianhydride monomer, and the 2,2-bis Wherein the polyimide resin is contained in an amount of 1 to 5 mol per mol of dianhydride (CBDA).
A polyimide film comprising the polyimide resin of any one of claims 1 to 6.
The polyimide film according to claim 7, wherein the polyimide film has a birefringence of 0.008 or less.
The polyimide film according to claim 7, wherein R _o (surface direction retardation) is 1 nm or less and R _th (thickness direction retardation) is 100 nm or less (thickness 10 to 12 μm).
The polyimide film according to claim 7, wherein the film has a transmittance of at least 88% at 550 nm when measured with a UV spectrometer based on a thickness of 10 to 12 μm.
The polyimide film according to claim 7, wherein a coefficient of thermal expansion (CTE) at 50 to 300 캜 is 40 ppm / 캜 or less.
A substrate for an image display device comprising the polyimide film of any one of claims 7 to 11.