KR101339663B1 - Transparent polyimide with low coefficient of thermal expansion - Google Patents

Abstract

The present invention provides a polyimide film excellent in transparency and excellent in heat resistance, which is useful for a transparent conductive film, a TFT substrate, a flexible printed circuit board, and the like.

Description

Transparent polyimide with low coefficient of thermal expansion

The present invention relates to a polyimide film which is colorless transparent and excellent in heat resistance.

Polyimides are widely used in various applications as molding materials, composite materials, electrical and electronic materials, optical materials, etc. because of their excellent heat resistance, mechanical properties, and electrical properties. The present invention is generally a polyimide film obtained by imide ring-cyclic reaction of a polyimide precursor composition and a polyimide precursor composition for obtaining a polyimide film having high transparency, low thermal expansion, high heat resistance, and low birefringence, and the polyimide film The present invention relates to a transparent flexible film for an electronic device such as an electronic paper, an organic EL display device, an LED lighting device, a CMOS (complementary metal oxide film semiconductor) sensor, and the like obtained by using a polyimide film.

In general, a polyimide (PI) film is a film of a polyimide resin. The polyimide resin is a solution polymerization of an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to prepare a polyamic acid derivative, followed by ring dehydration at high temperature. The high heat resistant resin manufactured by imidation is called. (PMDA) or biphenyltetracarboxylic acid dianhydride (BPDA) as the aromatic dianhydride component, and aromatic diamine components such as oxydianiline (ODA), tetracarboxylic dianhydride p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), methylenedianiline (MDA), and bisaminophenylhexafluoropropane (HFDA).

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, electrode protective films of TFT-LCDs, and recently, it is used in display materials such as optical fibers and liquid crystal alignment films, and also in transparent electrode films by containing conductive fillers in the films or coating them on surfaces. 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, 6262328 and Korean Patent Laid-Open No. 2003-0009437 disclose monomers having a curved structure connected to a linking group, such as -O-, -SO2-, CH2-, etc. to the m-position rather than the p-position, or -CF3. There have been reports of a novel polyimide structure having improved permeability and color transparency by using aromatic dianhydride dianhydride and an aromatic diamine monomer having substituents such as the like, but the thermal properties are not significantly reduced. 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 a flexible display.

Accordingly, the present invention is to provide a polyimide film that is colorless and transparent, and has excellent mechanical and thermal stability properties.

INDUSTRIAL APPLICABILITY The present invention is colorless and transparent, and has excellent mechanical and thermal stability properties, which can be used in various fields such as semiconductor insulating films, TFT-LCD insulating films, passivation films, liquid crystal alignment films, optical communication materials, solar cell protective films, and flexible display substrates. Polyimide resins and films can be provided.

According to one aspect of the present invention, in the polyimide produced by polymerizing a dianhydride monomer and a diamine monomer, the dianhydride monomer provides a polyimide, characterized in that a mixture of an aliphatic compound and an aromatic compound.

According to one embodiment, the dianhydride monomer is provided with a polyimide, characterized in that the mixture of 6FDA and PMDA and HPMDA.

According to another embodiment, the diamine monomer is TFMB, the (6FDA + PMDA + HPMDA): TFMB molar ratio is 1: 1, the molar ratio of TFMB: 6FDA: PMDA: HPMDA is 1: 0.1-0.5: 0.2-0.7 It is provided a polyimide characterized by being 0.1-0.5.

According to another aspect of the present invention, in the method for preparing a polyimide by polymerizing a dianhydride monomer and a diamine monomer, the dianhydride monomer is a mixture of an aliphatic compound and an aromatic compound, Is provided.

According to one embodiment, the dianhydride monomer is a mixture of 6FDA and PMDA and HPMDA, the diamine monomer is TFMB, the (6FDA + PMDA + HPMDA): TFMB molar ratio is 1: 1, and the TFMB: 6FDA: The molar ratio of PMDA: HPMDA is 1: 0.1-0.5: 0.2-0.7: 0.1-0.5, The polyimide manufacturing method is provided.

According to another embodiment, a polyimide manufacturing method is provided, wherein the four monomers are added in the order of TFMB, 6FDA, PMDA, HPMDA.

According to another aspect of the invention, there is provided a polyimide film production method comprising the following steps.

(a) filling the reactor with a solvent in a nitrogen atmosphere and maintaining the reactor at 5-20 ° C,

(b) dissolving TFMB in the reactor;

(c) mixing 6FDA into the reactor into which the TFMB is added, and mixing;

(d) adding PMDA to the reactor into which TFMB and 6FDA are added and mixing the same;

(e) adding HPMDA to the reactor to which TFMB, 6FDA, and PMDA are added, and mixing them,

(e) heating the reactor to 110-130 ° C. to proceed with the reaction to obtain a polyamic acid solution,

(f) casting the polyamic acid solution on a glass substrate and heat treating to obtain a polyimide film.

According to one embodiment, the solvent is DMAc, the casting is carried out to a thickness of 70-90 ㎛, the heat treatment is dried for 30 minutes to 2 hours with hot air of 130-170 ℃ to form a film and then the glass Provided is a method for producing a polyimide film, characterized in that it is carried out by peeling from a substrate for 6-10 hours in a vacuum oven from 60-100 ℃ to 200-300 ℃.

In the present invention, the abbreviations such as 6FDA, PMDA, HPMDA, and TFMB have the following meanings, respectively.

(1) HPMDA = 1,2,4,5-cyclohexanetetracarboxylic dianhydride

(2) TFMB = 2,2'-bis (trifluoromethyl) benzidine

(3) 6FDA = 2,2-bis (3,4-anhydridicarboxyphenyl) hexafluoropropane

(4) 4-APS = 4,4'-diaminodiphenyl sulfone

(5) PMDA = pyromellitic Dianhydride

(6) CHDA = 1,4-cyclohexyldiamine

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

After filling 270 mL of dimethylacetamide (DMAc) with nitrogen through a 1L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a cooler as a reactor, the temperature of the reactor was adjusted to 10 ° C, and then As the composition shown in Table 1 below, TFMB was added to completely dissolve, 6FDA was added and mixed, PMDA was added and mixed, and HPMDA was added and stirred for 12 hours. Thereafter, the mixture was stirred in a 120 ° C. oil bath for 20 minutes and then stirred at room temperature for 12 hours, thereby allowing a 1: 1 condensation reaction of the aromatic diamine and the aromatic dianhydride to proceed to obtain a polyamic acid solution. After the reaction was completed, the obtained solution was applied to the glass, cast at 80 μm, dried for 1 hour with hot air at 150 ° C., and the film was peeled off from the glass substrate to be fixed to the frame with a pin. The film on which the film was fixed was placed in a vacuum oven, heated slowly at 80 ° C. to 250 ° C. for 8 hours, and then slowly cooled to separate from the frame to obtain a polyimide film (thickness 50 μm).

Example 2-3

The experiment was conducted as in Example 1, except that only the composition of the monomer was changed as shown in Table 1 below.

Comparative Example 1-6

The experiment was conducted as in Example 1, except that only the composition of the monomer was changed as shown in Table 1 below.

Comparative Example 7

Instead of adding the monomer in the order of TFMB, 6FDA, PMDA, HPMDA, the experiment was carried out as in Example 1 except that the monomer was added in the order of TFMB, PMDA, 6FDA, HPMDA.

Test Methods

(1) Permeability and 50% blocking wavelength

The prepared film was measured for visible light transmittance and 50% blocking wavelength using a UV spectrometer (Varian, Cary 100). On the other hand, on the document printed with yellow letters and lines, the photo is placed with a polyimide film having a thickness of 100 μm prepared in Example 1 and a polyimide film having a thickness of 25 μm prepared in Comparative Example 4, respectively. Indicated.

(2) Yellowness

The prepared film was measured for yellowness according to ASTM E313 standard using a UV spectrometer (Varian, Cary100).

(3) whiteness

The prepared film was measured for whiteness according to ASTM E313 using a UV spectrometer (Varian, Cary 100).

(4) color coordinates

The prepared film was measured according to ASTM E 1347-06 standard using a UV spectrometer (Varian, Cary100),

(Illuminant) was based on the measured value by CIE D65.

(5) Glass transition temperature (Tg)

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

(6) coefficient of linear expansion (CTE)

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

Test result

As a result, it was confirmed that Example 1-3 and Comparative Example 1-6 show the results as shown in Table 2 below. However, in the case of Comparative Example 7, although the results are not shown in Table 2 below, not only the polymerization degree is significantly lowered, but also YI, Tg, CTE as well as permeability in terms of permeability, at least 10% and at most 35%. It was confirmed that the physical properties were greatly reduced until.

division Furtherance Molar ratio thickness Example One 6FDA + PMDA + HPMDA / TFMB 2.5: 5: 2.5: 10 50 2 6FDA + PMDA + HPMDA / TFMB 2: 4: 4: 10 50 3 6FDA + PMDA + HPMDA / TFMB 4: 4: 2: 10 50 Comparative Example One 6FDA / TFMB 10:10 50 2 PMDA / TFMB 10:10 50 3 HPMDA / TFMB 10:10 50 4 6FDA + PMDA / TFMB 2: 8: 10 50 5 6FDA + HPMDA / TFMB 5: 5: 10 50 6 PMDA + HPMDA / TFMB 8: 2: 10 50

division Permeability Color coordinates YI Tg CTE
(50-250 ℃) 380-780 nm 550 nm L a b Example One 93.7 96.0 92.1 -0.12 0.1 1.98 297 26 2 90.5 93.1 93.8 0.19 0.23 1.45 278 24 3 92.5 93.4 89.0 -0.17 0.54 1.57 285 29 Comparative Example One 82.3 85.1 86.5 -3.98 1.21 2.10 286 41 2 80.4 82.7 84.2 0.64 3.89 9.64 306 39 3 92.1 94.5 95.6 -2.13 0.08 1.03 243 32 4 83.4 88.9 87.3 0.77 1.89 5.06 296 25 5 88.3 91.1 95.4 -0.54 1.36 3.45 267 27 6 82.1 84.7 91.1 0.42 1.1 7.78 275 26

Color coordinates (L * 100 = white, 0 = black, + a * = red, -a * = green, + b * = yellow, -b * = blue)

Claims (8)

delete delete delete delete delete In the method for producing a polyimide by polymerizing a dianhydride monomer and a diamine monomer,
The dianhydride monomer is a mixture of 6FDA and PMDA and HPMDA,
The diamine monomer is TFMB,
The (6FDA + PMDA + HPMDA): TFMB molar ratio is 1: 1,
The molar ratio of TFMB: 6FDA: PMDA: HPMDA is 1: 0.1-0.5: 0.2-0.7: 0.1-0.5,
Method for producing a polyimide, characterized in that the four monomers are added in the order of TFMB, 6FDA, PMDA, HPMDA. delete delete