TW202323390A - Polyamic acid composition and polyimide film prepared with the same - Google Patents

Abstract

The present disclosure relates to a polyamic acid composition comprising: a polyamic acid comprising, as a polymerization unit, at least one selected from a dianhydride monomer represented by Chemical Formula 1 and a diamine monomer represented by Chemical Formula 2 or Chemical Formula 3; an imidazole-based compound; an epoxy-based compound; and an organic solvent, and a polyimide comprising the same. The polyamic acid composition of the present disclosure and the polyimide comprising the same have excellent mechanical properties such as strength and elongation while maintaining a low yellow index and excellent thermal properties.

Description

Polyamide acid compound and polyimide film prepared therefrom

The present disclosure relates to a polyamic acid composition and a polyimide film prepared therefrom. Specifically, the present disclosure relates to a polyamic acid composition for manufacturing a display substrate and a polyimide film as a cured product of polyamic acid.

Displays of all types and sizes, from small displays like mobile phones to LCD or plasma TVs or outdoor signage (public information displays (PIDS) and digital information displays (DIDs)). Especially as the society develops into the era of popularization, that is, an advanced knowledge and information society, the demand for portable devices with simplicity and mobility is booming. In contrast, the technology of thinner, lighter, more portable, and flexible displays that can be folded like paper and rolled like a scroll is emerging, and is becoming a new growth engine business.

Under such circumstances, polyimide films prepared by curing and imidizing polyamic acid (prepared by polymerizing dianhydride monomers and diamine monomers) have excellent heat resistance, chemical resistance, Due to its mechanical strength, electrical properties, and dimensional stability, it is widely used in the field of electrical/electronic devices and semiconductor fields. In particular, there has been growing interest in thin films as substrate materials for flexible displays.

However, in order to use a film for display applications, it needs to have high transparency, high mechanical strength, optical properties, yellowing index, and mechanical properties without micro-defects such as curling or cracks caused by folding.

Accordingly, there is a need to develop polyimides having a low yellowing index, which are suitable for use in flexible substrates, and which maintain excellent thermal properties such as heat resistance while having excellent strength and elongation.

[Technical Issues] The purpose of the present disclosure is to provide a polyamic acid compound having excellent elongation and strength while maintaining a low yellowing index and excellent thermal properties, and a polyimide film prepared therefrom.

In addition, another object of the present disclosure is to provide a flexible display device using the above-mentioned polyimide film as a substrate.

[technical means] The present disclosure may have various changes and may have multiple embodiments, so specific embodiments will be described in detail as shown in the drawings. However, these descriptions are not intended to limit the present disclosure to specific embodiments, but should be understood to include all modifications, equivalents and substitutions included within the spirit and scope of the present disclosure.

The terms used in this case are used to describe specific embodiments only, and are not intended to limit the present disclosure. A singular expression includes a plural expression unless the context clearly states otherwise. In this case, terms such as "comprising", "having" and the like are intended to represent the features, numbers, steps, operations, components and combinations thereof described in the specification. It should be understood that these terms do not preclude the existence or addition of one or more other features or quantities, steps, operations, components, parts or combinations thereof.

When an amount, concentration or other value or parameter is given by way of recitation of a range, preferred range or preferred upper limit, and preferred lower limit, it is to be understood that from any range upper or preferred value and any range lower or preferred value All ranges formed by any pair of in are specifically revealed, whether or not the ranges are individually disclosed.

When numerical ranges are stated herein, unless otherwise stated, the range is not limited to the endpoints, and the scope of the disclosure within that range is not limited to the specific values recited when defining the range.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Terms such as those defined in commonly used dictionaries should be understood to have meanings consistent with those in the relevant technical context, and should not be interpreted as ideal or overly formalized meanings, unless clearly defined in this case. Specific details for implementing the present disclosure will be described below.

The present disclosure relates to a polyamic acid composition.

[化學式2]

[化學式3]

咪唑基（imidazole-based）化合物；環氧基（epoxy-based）化合物；以及有機溶劑。 In one general aspect of the present disclosure, the polyamic acid composition may include: polyamic acid, including, as a polymerized unit, at least one selected from the following: dianhydride monomers represented by Chemical Formula 1 and represented by Chemical Formula 2 or Chemical Formula Among the diamine monomers shown in 3: [Chemical Formula 1]

[chemical formula 2]

[chemical formula 3]

imidazole-based compounds; epoxy-based compounds; and organic solvents.

The polyamic acid composition prepared according to the present disclosure has excellent thermal properties unique to polyimides, has low yellowing index, and also has excellent mechanical properties, such as strength and elongation. Therefore, the polyamic acid composition is suitable as a material for a display, and a polyimide film which is a cured product of the polyamic acid composition is useful as a material for a display substrate.

（CpODA）

（CpODA-tee）

（CpODA-cee） In this disclosure, the compound represented by Chemical Formula 1 is called norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″- Tetracarboxylic dianhydride (norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid dianhydride, CpODA), CpODA can be a stereoisomer A mixture or can be a specific stereoisomer. Stereoisomers are not particularly limited, but preferred stereoisomers may include trans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5 ,5″,6,6″-tetracarboxylic dianhydride (trans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6" -tetracarboxylic dianhydride, CpODA-tee) and cis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″ -Tetracarboxylic dianhydride (cis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic dianhydride, CpODA-cee) .

(CpODA)

(CpODA-tee)

(CpODA-cee)

In one embodiment, at least 50 molar % or more, even more preferably, 63 molar % or more of the CpODA may be CpODA-tee. In another illustration, at least 30 molar % or more, even more preferably at least 37 molar % or more of the CpODA can be CpODA-cee. In another example, the total amount of CpODA-tee and CpODA-cee in CpODA can be at least 80 mol% or more, even more preferably, 83 mol% or more, but the content range is not limited thereto.

In this disclosure, the compound represented by Chemical Formula 2 is called 4,4'-diaminobenzanilide (DABAN), and the compound represented by Chemical Formula 3 is called N,N '-bis(4-aminophenyl)benzene-1,4-dicarboxamide (N,N'-bis(4-aminophenyl)benzene-1,4-dicarboxamide, DATA).

In the present disclosure, the polyamic acid composition may also include a dianhydride monomer represented by Chemical Formula 4, and may have polymerized units accompanying the dianhydride monomer: [Chemical Formula 4]

The compound shown by chemical formula 4 is called (4arH, 8acH)-decahydro-1t, 4t:5c, 8c-xylene-2c, 3c, 6c, 7c-tetracarboxylic dianhydride ((4arH, 8acH)- decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylic dianhydride, DNDAxx).

In the present disclosure, the dianhydride monomer represented by Chemical Formula 4 may contain 20 mol % or less, preferably 15 mol % or less, 13 mol % or less of the total dianhydride monomer component ratio , 10 mol% or less, 8 mol% or less, 7 mol% or less, 5 mol% or less, 3 mol% or less, or 2 mol% or less , or 0 mole%.

In the present disclosure, the diamine monomer represented by Chemical Formula 2 may contain 70 mol % or more of the total diamine monomer component ratio, and the lower limit of the ratio may be, for example, 75 mol %, 78 mol %, 80 mol%, 82 mol%, 85 mol%, 87 mol%, 90 mol%, 92 mol%, 94 mol%, 95 mol%, 97 mol%, 99 mol% %, or 100 mol% or more, and the upper limit of the ratio may be, for example, 100 mol%, 99 mol%, 98 mol%, 97 mol%, 96 mol%, 95 mol%, 94 mol%, 93 mol%, 92 mol%, 91 mol%, 90 mol%, or 88 mol% or less.

In the present disclosure, by using an imidazole-based compound suitable for polyamic acid, polyimide having excellent mechanical properties such as transparency, elongation, and brittleness (strength) can be prepared.

In this disclosure, the imidazole-based compound may include one or a combination of 2-phenylimidazole, benzimidazole, 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, and imidazole . Preferably the imidazolyl compound may be 2-phenylimidazole or benzimidazole, more preferably 2-phenylimidazole.

In addition, in the present disclosure, based on 1 mol of the repeating unit of polyamide acid, the content of the imidazole-based compound may be 0.1 to 40 mol%. The lower limit of the ratio can be, for example, 0.5 mol%, 1.0 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, 3 mol%, 3.5 mol%, 4.0 mol%, 4.5 mol% Mole %, 4.7 mol %, 4.9 Mole %, 5.0 Mole %, 5.2 Mole %, 5.5 Mole %, 6.0 Mole %, 6.5 Mole %, 7.0 Mole %, 7.5 Mole %, 8.0 Mole %, 8.5 mol%, 9.0 mol%, 9.5 mol%, or 10 mol% or more, and the upper limit of the ratio may be, for example, 35 mol%, 30 mol%, 28 mol%, 26 mol%, 24 mol%, 22 mol%, 20 mol%, 18 mol%, 15 mol%, 12 mol%, or 10 mol% or less. When the content of the imidazole-based compound is too small, for example, when the content of the imidazole-based compound is less than 0.1 mol%, problems such as elongation, brittleness, and strength may decrease in mechanical properties. On the other hand, when the content of imidazole-based compounds is too much, for example, when the content of imidazole-based compounds is greater than 40 mol%, the polyamic acid composition may have poor storage stability.

In the present disclosure, epoxy-based compounds are multifunctional epoxy compounds. Multifunctional epoxy compounds may include epoxy compounds having 2 to 4 epoxy functional groups such as N,N'-N,N'-tetraglycidyl diaminodiphenylmethane (N,N'-tetraglycidyl diamino diphenyl methane, TGDDM), bisphenol A diglycidyl ether (bisphenol A diglycidyl ether, DGEBA), tetraglycidyl-meta-xylenediamine (tetraglycidyl-meta-xylenediamine), tetraglycidyl-1,3-diamine Tetraglycidyl-1,3-bisaminomethylcyclohexane, trimethylolpropane triglycidyl ether (TMP), etc., and preferably TGDDM. The polyamic acid composition prepared in the present disclosure contains an epoxy compound as an additive, so that the crosslink density can be increased to have rigid mechanical properties.

In addition, in the present disclosure, the content of the epoxy compound may be 0.01 to 1.0 mol % based on 1 mol of the repeating unit of polyamide acid. The lower limit of the proportion may be, for example, 0.02 mol%, 0.03 mol%, 0.05 mol%, 0.07 mol%, or 0.09 mol% or more, and the upper limit of the proportion may be, for example, 0.9 mol% , 0.85 mol%, 0.8 mol%, 0.75 mol%, 0.7 mol%, 0.65 mol%, 0.6 mol%, 0.55 mol%, 0.5 mol%, 0.48 mol%, 0.45 mol% , 0.4 mol%, 0.35 mol%, or 0.3 mol% or less.

In the present disclosure, the strength of polyimide can be improved by adding epoxy compounds. However, based on the repeating unit of 1 mol of polyamide acid, when the content of epoxy compound is less than 0.01 mol%, the effect of increasing the strength of polyimide due to the addition of epoxy compound may not be significant. When its content is more than 1.0 mol%, physical properties may be lowered due to lowered mutual solubility.

The polyamic acid composition of the present disclosure may contain both an imidazole-based compound and an epoxy-based compound in the polyamic acid, so it can be expected to have high strength and excellent elongation at the same time. In particular, the polyimide of the present disclosure exhibits high strength and excellent elongation as well as improved heat resistance and yellowing index. In addition, the elongation is further increased by containing epoxy-based compounds such as TGDDM, thus realizing that polyimide has improved mechanical properties and at the same time has excellent thermal properties suitable as a display substrate material.

In the present disclosure, the organic solvent is not particularly limited as long as it can dissolve polyamic acid, imidazole-based compounds, and epoxy-based compounds, but may be, for example, an aprotic polar solvent, preferably, As an organic solvent N-methyl-pyrrolidone (N-methyl-pyrrolidone, NMP), N,N'-dimethylformamide (N,N'-dimethylformamide, DMF), N,N'-diethylformamide Amine (N,N'-diethylformamide, DEF), N,N'-dimethylacetamide (N,N'-dimethylacetamide, DMAc), dimethylpropanamide (DMPA), N,N- Diethylacetamide (685-91-6, N,N-diethylacetamide, DEAc), and 3-methoxy-N,N-dimethylacrylamide (53185-52-7, 3-methoxy- N,N-dimethylpropanamide, KJCMPA), etc. or a combination of the foregoing, but NMP can be used most preferably.

In the present disclosure, the polyamic acid composition prepared in the present disclosure may have a weight average molecular weight of 1,000 g/mol to 100,000 g/mol. The lower limit of the weight average molecular weight can be 1,500 g/mol, 2,000 g/mol, 2,500 g/mol, or 3,000 g/mol or higher, and the upper limit of the weight average molecular weight can be 90,000 g/mol, 80,000 g/mol mol, 70,000 g/mol, 60,000 g/mol, 50,000 g/mol, 30,000 g/mol, 29,000 g/mol, or 28,500 g/mol or less.

In the present disclosure, the polyamic acid composition prepared in the present disclosure may have a solid content of 5 wt % to 30 wt %. The lower limit of the weight percentage of solid content can be 5wt%, 8wt%, 9wt%, 10wt%, 15wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt% %, or 29 wt% or more, and the upper limit of the weight percentage of solid content can be 29wt%, 27 wt%, 25wt%, 23wt%, 21wt%, 20wt%, 19wt%, or 18wt% or less. By adjusting the solid content of the polyamic acid composition, the increase of viscosity can be controlled and the process time in the curing process can be shortened.

In the present disclosure, the polyamic acid composition may have a viscosity ranging from 1,000 centipoise to 10,000 centipoise, which is measured at a temperature of 23° C. and a shear rate of 1 s ⁻¹ . For example, the upper limit of viscosity can be 10,000 centipoise, 8,000 centipoise, 5,000 centipoise, 4,700 centipoise, 4,500 centipoise, 4,000 centipoise, 3,800 centipoise, 3,700 centipoise, 3,500 centipoise, 3,300 centipoise, 3,200 centipoise , 3,100 centipoise, or 3,000 centipoise or less, and the lower limit thereof is not particularly limited, but may be 1,200 centipoise, 1,500 centipoise, 2,000 centipoise, or 2,500 centipoise or more. Viscosity can be measured using, for example, a Haake Rheostress 600 manufactured by Thermo Fisher Scientific Inc., at a shear rate of 1 s ⁻¹ , a temperature of 23° C., and a plate gap of 1 measured in millimeters. The present disclosure can provide a precursor composition with excellent processability by adjusting the viscosity range.

In addition, the present disclosure provides a polyimide, which is a cured product of the above-mentioned polyamic acid composition, and the polyimide can be prepared into a thin film for physical property analysis.

Therefore, in another aspect of the present disclosure, a polyimide film comprising the cured product of the polyamic acid composition is provided.

In this disclosure, in addition to the coefficient of thermal expansion (CTE) and the glass transition temperature (Td), which are mainly used as standards for judging the thermal properties of polyimide, the glass transition temperature (thermal decomposition temperature) , Tg) was able to predict thermal properties while also ensuring mechanical properties, which was confirmed.

In the present disclosure, polyamic acid may have a coefficient of thermal expansion in the range of 3ppm/°C to 20ppm/°C, for example, the upper limit of the coefficient of thermal expansion may be 19ppm/°C, 18ppm/°C, 16ppm/°C, 14ppm/°C, 12ppm /°C, 10ppm/°C, or 8 ppm/°C or less, and its lower limit can be, for example, 4ppm/°C, 4.5ppm/°C, 5.0ppm/°C, 5.5ppm/°C, 6.0ppm/°C, 6.5ppm/°C °C, or 7ppm/°C or greater. In one embodiment, the coefficient of thermal expansion may be measured at 100°C to 400°C. For the measurement of the coefficient of thermal expansion, a Thermodynamic Analyzer Model Q400 manufactured by Waters Taiwan Branch (TA Instruments) can be used. Specifically, the coefficient of thermal expansion can be determined by making polyimide into a film, cutting the film into a size of 2 mm in width and 10 mm in length, and then applying a tension of 0.05 Newton to the polyimide film in a nitrogen atmosphere. , by increasing the temperature from room temperature to 400°C at a rate of 10°C/min, followed by cooling again at a rate of 10°C/min, the slope of the segment from 100°C to 350°C was measured.

In addition, in the present disclosure, the glass transition temperature of the polyamic acid composition may be in the range of 370°C or higher, for example, the lower limit of the glass transition temperature may be 375°C, 380°C, 385°C, or 390°C or more High, while the upper limit of the glass transition temperature can be 600°C or lower. The glass transition temperature can be measured using a thermodynamic analyzer at 10° C./min for the polyimide prepared by curing the polyamic acid composition.

In the present disclosure, the polyimide obtained by curing the polyamic acid composition may have a thermal decomposition temperature of 470° C. or higher to lose 5 wt%. The thermal decomposition temperature can be measured using a thermogravimetric analyzer (Q50) manufactured by Waters Taiwan Branch (TA Instruments). In a specific illustration, the polyimide obtained by curing the polyamic acid composition is heated to 150° C. at a rate of 10° C./min in a nitrogen atmosphere, and then held at temperature for 30 minutes to remove moisture. Then, 10 The temperature was raised to 600°C at a rate of °C/min to measure the temperature at which 5 wt% weight loss occurred. The lower limit of the thermal decomposition temperature may be, for example, 470°C, 475°C, 480°C, 482°C, 484°C, 486°C, 488°C, 490°C, 492°C, 494°C, 496°C, 498°C, 500°C, 505°C , 506°C, 507°C, 508°C, 509°C, or 510°C or higher, while the upper limit may be, for example, 800°C, 750°C, 700°C, 650°C, 630°C, or 600°C or lower.

In addition, the polyimide obtained by curing the polyamic acid composition has an elongation of 6% or more, such as 7%, 8%, 9%, 10% or more, and the upper limit of the elongation is not particularly Limit, but can be less than 40%. The elongation can be obtained by curing the polyamic acid composition into a polyimide film, cutting the polyimide film into a size of 10 mm wide and 40 mm long, and then using The Instron5564 UTM equipment was used to measure elongation by ASTM D-882 method.

In the present disclosure, the film-like polyimide obtained by curing the polyamic acid composition has a thickness of 10±0.5 μm, and when the yellow index (YI) is measured, the yellow index is less than 10, preferably 7 or less, more preferably 5 or less, still more preferably 3.5 or less. When a polyimide film is used for a light-transmitting part such as a substrate for a display, the polyimide film needs to have transparency, more precisely, colorless (colorless) transparency. This means that the smaller the absolute value of the yellowing index, the closer the color of the film is to colorless (colorless). If the yellowness index is 10 or less, particularly preferably 5 or less, when measured at a film thickness of 10±0.5 μm, the generally desired colorlessness can be ensured. In addition, the yellowness index tends to increase as the film thickness increases. Also, the yellowing index is preferably 0 or more.

In the present disclosure, regarding the strength of polyimide obtained by curing the polyamic acid composition, the degree of strength improvement can be obtained by fixing polyimide having a width of 50 mm, a length of 50 mm, and a thickness of 10±0.5 μm. To measure the imide film, fold and bend the film repeatedly, and observe the cracks and breaks with the naked eye to confirm the degree of cracks and breaks according to the number of folds.

[化學式2]

2-苯基咪唑；N-甲基吡咯烷酮（NMP）以及N,N'-四縮水甘油基二氨基二苯甲烷（TGDDM）。 In another aspect of the present disclosure, a polyamic acid composition is provided, which includes: polyamic acid, including, as a polymerized unit, a dianhydride monomer represented by Chemical Formula 1 and a diamine represented by Chemical Formula 2 Monomer: [Chemical Formula 1]

[chemical formula 2]

2-Phenylimidazole; N-methylpyrrolidone (NMP) and N,N'-tetraglycidyldiaminodiphenylmethane (TGDDM).

The contents of 2-phenylimidazole as the imidazole-based compound and TGDDM as the epoxy-based compound are the same as described above.

[化學式2]

[化學式3]

2-苯基咪唑；N-甲基吡咯烷酮（NMP）以及N,N'-四縮水甘油基二氨基二苯甲烷（TGDDM）。 In yet another aspect of the disclosure, a polyamic acid composition is provided, which includes: polyamic acid, including, as a polymerized unit, a dianhydride monomer represented by chemical formula 1 and chemical formula 2 or chemical formula 3 The diamine monomer: [Chemical Formula 1]

[chemical formula 2]

[chemical formula 3]

2-Phenylimidazole; N-methylpyrrolidone (NMP) and N,N'-tetraglycidyldiaminodiphenylmethane (TGDDM).

Here, 90 mol % of the diamine monomer represented by Chemical Formula 2 and 10 mol % of the diamine monomer represented by Chemical Formula 3 may be included in the total diamine monomer components.

In addition, the contents of 2-phenylimidazole as an imidazole-based compound and TGDDM as an epoxy-based compound are the same as described above.

在化學式5中，R ₁和R ₂為相同或不同，且各自獨立表示氫原子、C ₁-C ₆烷基或C ₃-C ₉烷基甲矽烷基； 在化學式5所示之聚醯胺酸的整個重複單元中，70莫耳%或更多、優選地80莫耳%或更多、更優選地90mol％或更多，甚至更優選地100莫耳%的A部分是由化學式1所示之二酐單體的衍生結構；以及 [化學式1]

在由化學式5所示之聚醯胺酸的整個重複單元中，W部分是由化學式2及/或化學式3所示之二胺單體的衍生結構。此處，70莫耳%或更多、優選地80莫耳%或更多、以及更優選地90莫耳%或更多的W部分是由化學式2所示之二胺單體的衍生結構： [化學式2]

[化學式3]

In yet another aspect of the present disclosure, the polyamic acid composition prepared by the present disclosure may include: a polyamic acid having a repeating unit represented by Chemical Formula 5; an imidazole-based compound; an epoxy-based compound; and an organic solvent: [ Chemical formula 5]

In chemical formula 5, R ₁ and R ₂ are the same or different, and each independently represents a hydrogen atom, C ₁ -C ₆ alkyl or C ₃ -C ₉ alkyl silyl; in the polyamide shown in chemical formula 5 In the entire repeating unit of the acid, 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 100 mol% of moiety A is represented by chemical formula 1 The derived structure of the dianhydride monomer shown; and [Chemical Formula 1]

In the entire repeating unit of polyamic acid represented by Chemical Formula 5, the W part is a derivative structure of the diamine monomer represented by Chemical Formula 2 and/or Chemical Formula 3. Here, 70 mol% or more, preferably 80 mol% or more, and more preferably 90 mol% or more of the W moiety is a derived structure of a diamine monomer shown in Chemical Formula 2: [chemical formula 2]

[chemical formula 3]

The types and contents of the imidazole-based compound, the epoxy-based compound, and the organic solvent are the same as described above.

By measuring the thermal decomposition temperature, thermal expansion coefficient, and glass transition temperature with weight percent loss, it was confirmed that the polyimide according to the present disclosure has a low yellowing index level suitable for display substrates, and maintains the polyimide Unique excellent thermal properties. In addition, the polyimide according to the present disclosure has high strength while maintaining excellent elongation, as shown by elongation measurement and brittleness analysis.

The ingredients and content of the optimal polyamic acid composition according to the present disclosure were identified to achieve thermal properties, mechanical properties, and transparency suitable for display substrates as described above.

Therefore, the polyamic acid composition according to the present disclosure and the polyimide prepared therefrom can be advantageously used in substrates such as display substrates.

In yet another aspect of the present disclosure, the present disclosure provides a flexible display, which includes the polyimide film as a substrate, and the polyimide film is prepared from the aforementioned polyamide acid composition.

[Beneficial effect] The polyamic acid composition according to the present disclosure and the polyimide comprising the polyamic acid composition may have excellent mechanical properties such as strength and elongation while maintaining a low yellowness index and excellent thermal properties.

The following examples are provided to help understand the present disclosure. In order to understand the present disclosure more easily, the following examples are provided, and the content of the present disclosure is not limited by these examples.

< get together Acyl Preparation of amino acid composition >

Example 1 : poly Acyl Amino acid composition

DABAN and N-methyl-2-pyrrolidone were put into a reaction vessel filled with nitrogen, and the mixture was stirred at a temperature of 50° C. for 1 hour. Slowly add CpODA to the stirred solution, stir at room temperature for 4 hours or more, and react until the viscosity does not change, thereby obtaining polyamic acid.

Based on 1 mol of the repeating unit of the polyamic acid, add 20 mol% of 2-phenylimidazole as the imidazole-based compound, and based on 1 mol of the repeating unit of the polyamic acid, add 0.08 mol TGDDM of ear % is used as the epoxy compound of cross-linking agent. Next, the resulting mixture was stirred at room temperature for 3 hours and reacted until the viscosity did not change, thereby preparing a polyamic acid composition.

Example 2 to 11 : poly Acyl Amino acid composition

As shown in Table 1, the polyamic acid composition was prepared by the same method as in Example 1, except for the monomer component and its content ratio, the content ratio of the imidazole-based compound and the content ratio of the epoxy-based compound were adjusted.

[Table 1] Classification Dianhydride (mole%) Diamine (mole%) Imidazole-based compound (mole%) Epoxy Compound (Mole%) CpODA DABAN DATA 2-Phenylimidazole TGDDM Example 1 100 90 10 20 0.08 Example 2 100 90 10 10 0.08 Example 3 100 90 10 20 0.48 Example 4 100 90 10 5 0.03 Example 5 100 90 10 5 0.08 Example 6 100 90 10 5 0.16 Example 7 100 100 - 20 0.07 Example 8 100 100 - 20 0.14 Example 9 100 100 - 5 0.07 Example 10 100 100 - 10 0.07 Example 11 100 100 - 20 0.07

The abbreviations of the compounds used in the following various examples are as follows. Norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic dianhydride: CpODA 4,4'-Diaminobenzylaniline: DABAN N,N'-bis(4-aminophenyl)benzene-1,4-dimethylamide: DATA N-Methylpyrrolidone: NMP

EXPERIMENTAL EXAMPLES. Gathering revealed by this book Acyl Analysis of physical properties of polyimide prepared from amine-acid composition.

< Preparation of polyimide for physical property measurement >

From each of the polyamic acid compositions prepared in Examples 1 to 11, air bubbles were removed by rotating at a high speed of 1,500 rpm or higher. Next, each defoamed polyamic acid composition was applied to a glass substrate using a spin coater.

In a nitrogen atmosphere, the temperature was raised from room temperature to 400°C at a rate of 4°C/min, and the product was heat-treated at 400°C for 60 minutes, and then cooled to 30°C at a rate of 4°C/min to obtain a film shape of 10±0.5 microns Polyimide.

Experimental example 1 : Thickness measurement

The thickness of the polyimide prepared according to the foregoing examples was measured using an electric film thickness tester manufactured by Anritsu Corporation.

Experimental example 2 : viscosity measurement

For the polyamic acid composition prepared in the example, a Haake Rheostress 600 manufactured by Thermo Fisher Scientific Inc. was used, and the shear rate was 1s ^-1 , temperature Viscosity was measured at 23°C with a plate gap of 1 mm.

Experimental example 3 : Yellowness index measurement

For the polyimides prepared according to the previous examples, the yellowness index was measured using a colorimeter from Hunter Lab.

Experimental Example 4 : thermal decomposition temperature with weight percent loss ( Thermal Decomposition Temperature, Td )

Using a thermogravimetric analyzer model Q50 manufactured by Waters Taiwan Branch (TA Instruments), the polyimide film was heated to 150 °C at a rate of 10 °C/min in a nitrogen atmosphere, and then held for 30 minutes to Remove moisture. Next, the temperature was raised to 600°C at a rate of 10°C/min, and the temperature at which the weight loss was 5% was measured.

Experimental example 5 :Thermal expansion coefficient( Coefficient of Thermal Expansion , CTE )Measure

A thermomechanical analyzer model Q400 manufactured by Waters Taiwan Branch (TA Instruments) was used. Specifically, film-like polyimide was cut into a size of 2 mm in width and 10 mm in length. Apply a tension of 0.05 Newton to the polyimide film in a nitrogen atmosphere, raise it from room temperature to 400°C at a rate of 10°C/min, and then cool it again at a rate of 10°C/min to measure the cross-section from 100°C to 350°C slope.

Experimental example 6 : glass transition temperature ( Glass Transition Temperature, Tg )

For the polyimide film prepared from the polyamic acid composition in the embodiment, a thermomechanical analyzer (thermomechanical analyzer, TMA) is used to measure the rapid expansion point under the condition of 10°C/min.

Experimental example 7 :Elongation

The polyimide film prepared by the polyamic acid composition of the embodiment was cut into a size of 10 mm wide and 40 mm long, and the Instron5564 UTM equipment from Instron Corp was used to pass the ASTM D -882 method to determine elongation.

Experimental example 8 : strength analysis

For the polyimide film prepared by the polyamic acid composition of the embodiment, the polyimide film is cut into a size of 50 mm wide and 50 mm long (thickness 10 mm), by aligning the two ends of the film, repeatedly The strength of each polyimide film was analyzed by folding (180°) and bending the film, and visually observing cracks and fractures. When the film is folded 5 times or more, the case where there are no cracks and breaks is judged as A+, and the case where it is folded 5 times or more but with small cracks is judged as A-, up to 3 times, but if in subsequent folds If it breaks, it is awarded a B+, and can be folded up to 2 times, but if it breaks in a subsequent fold, it is awarded a B-.

[Table 2] Classification Solid content (%) Viscosity (cps) Thickness (microns) Yellowing Index (YI) Td 5% (℃) CTE (ppm/℃) Tg (℃) Elongation(%) Brittleness (strength) Example 1 18 2,890 9.8 3.4 506 7 393 9 ^A- Example 2 18 2,890 10.0 3.8 508 9 405 8 ^A- Example 3 18 2,890 10.0 3.9 506 10 392 9 ^A- Example 4 18 2,890 10.3 3.5 508 7 400 7 B ⁺ Example 5 18 2,890 10.0 3.4 508 7 390 8 B ⁺ Example 6 18 2,890 10.1 3.4 508 8 383 7 B ⁺ Example 7 18 4,530 10.1 3.1 506 9 393 9 ^A- Example 8 18 4,530 9.8 3.0 507 9 386 8 ^A- Example 9 18 4,530 10.0 3.2 511 8 397 7 B ⁺ Example 10 18 4,530 9.7 2.9 509 9 391 6 B ⁺ Example 11 18 4,530 10.2 3.1 507 9 386 7 B ⁺

Details that can be fully understood and understood by those skilled in the art to which the present disclosure pertains are omitted from the specification. Other than the specific examples described in this specification, various modifications can be made within the scope of not changing the technical spirit or basic structure of the present disclosure. Accordingly, the present disclosure may be practiced otherwise than as specifically described and illustrated herein, as will be understood by those of ordinary skill in the art to which this disclosure pertains.

Claims (20)

A polyamic acid composition, comprising: a polyamic acid, comprising, as a polymer unit, at least one selected from the following: a dianhydride monomer represented by chemical formula 1 and a dihydrogen monomer represented by chemical formula 2 or chemical formula 3 Among the amine monomers: [Chemical Formula 1]

[chemical formula 2]

[chemical formula 3]

an imidazole-based compound; an epoxy-based compound; and an organic solvent. The polyamic acid composition as claimed in item 1, wherein the imidazole-based compound is selected from 2-phenylimidazole, benzimidazole, 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole , and at least one of the group consisting of imidazole. Such as the polyamic acid composition of claim 1, wherein the organic solvent is selected from N-methylpyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethyl Dimethylacetamide (DEF), N,N'-dimethylacetamide (DMAc), dimethylacrylamide (DMPA), N,N-diethylacetamide (DEAc), and 3- At least one of the group consisting of methoxy-N,N-dimethylacrylamide (KJCMPA). The polyamic acid composition as claimed in claim 1, wherein the epoxy compound is a multifunctional epoxy compound. Such as the polyamic acid composition of claim 4, wherein the epoxy compound is selected from N,N'-N,N'-tetraglycidyl diaminodiphenylmethane (TGDDM), bisphenol A diglycidyl Group consisting of ether (DGEBA), tetraglycidyl-m-xylylenediamine, tetraglycidyl-1,3-bisaminocyclohexane, and trimethylolpropane triglycidyl ether (TMP) at least one of the group. The polyamic acid composition as claimed in item 1, wherein the polyamic acid further comprises a dianhydride monomer shown by chemical formula 4: [chemical formula 4]

The polyamic acid composition as claimed in item 6, wherein the content of the dianhydride monomer represented by chemical formula 4 is 20 mol% or less of the total dianhydride monomer components. The polyamic acid composition as claimed in claim 1, wherein the content of the diamine monomer represented by chemical formula 2 is 70 mole % or more of the total diamine monomer components. The polyamic acid composition according to claim 1, wherein the content of the imidazole-based compound is 0.1 to 40 mol% based on 1 mol of the repeating unit of the polyamic acid. The polyamic acid composition according to claim 1, wherein the content of the epoxy compound is 0.01 to 1.0 mol% based on 1 mol of the repeating unit of the polyamic acid. The polyamic acid composition according to claim 1, wherein a weight average molecular weight is in the range of 1,000 g/mol to 100,000 g/mol. As the polyamic acid composition of claim 1, wherein a solid content is in the range of 5wt% to 30wt%. The polyamic acid composition according to claim 1, wherein a viscosity is in the range of 1,000 centipoise to 10,000 centipoise, and the viscosity is measured at a temperature of 23° C. and a shear rate of 1 s ⁻¹ . The polyamic acid composition according to claim 1, wherein the coefficient of thermal expansion (coefficient of thermal expansion, CTE) after curing is in the range of 3 ppm/°C to 20 ppm/°C. The polyamic acid composition according to claim 1, wherein a glass transition temperature (glass transition temperature, Tg) after curing is 370° C. or higher. The polyamic acid composition as claimed in claim 1, wherein the thermal decomposition temperature (thermal decomposition temperature, Td) of 5 wt% loss after curing is 470°C or higher. The polyamic acid composition as claimed in claim 1, wherein the elongation after curing is 6% or more. The polyamic acid composition according to claim 1, wherein the yellowing index (yellow index, YI) after curing is 10 or less. A polyimide film, comprising a cured product of the polyamide acid composition according to any one of claim 1 to claim 18. A flexible display device comprising the polyimide film as claimed in claim 19 as a substrate.