TWI659064B - Resin composition for display substrate, resin film for display substrate, and method for manufacturing resin film for display substrate - Google Patents

Abstract

According to the present invention, there is provided a resin composition for a display substrate that can form a resin film for a display device substrate having high heat resistance, a moderate coefficient of linear expansion, and high tensile strength. The present invention can solve the above-mentioned problems by including a resin composition for a display substrate containing a polyamic acid having a structural unit represented by Formula (1) and having a weight average molecular weight of 10,000 or more, and an organic solvent. Here, in formula (1), X ¹ represents a tetravalent aromatic group of formula (3), Y ¹ represents a group represented by formula (P), and n represents the number of repeating units.

Description

Resin composition for display substrate, resin film for display substrate, and method for manufacturing resin film for display substrate

This invention relates to the manufacturing method of the resin composition for display substrates, the resin film for display substrates, and the resin film for display substrates.

In recent years, in the field of display devices such as organic electroluminescence displays and liquid crystal displays, in addition to high precision, requirements for weight reduction and flexibility have been increasing. In this case, it has been known that polyimide resins which are easy to produce and have high heat resistance have been attracting attention as a substrate material for displays in place of glass.

However, when using polyimide as a material for a display substrate, it is necessary to have a value close to the linear expansion coefficient of the glass (about 3 to 10 ppm / K). The coefficient of linear expansion is not suitable for the substrate material of the display.

When an active matrix driven panel is used in a high-precision display to form an active matrix layer containing thin-film active elements in addition to the matrix-shaped pixel electrodes, in addition to the high temperature processing of about 300 to 500 ° C, It also needs to be correctly aligned. However, polyimide is inferior to glass in terms of the coefficient of linear expansion, so it has greater shrinkage or expansion than glass substrates at high temperatures. Therefore, when using polyimide as a substrate material, it is often difficult to maintain high dimensional stability during the manufacturing process of the display.

Therefore, in order to make use of the heat resistance of polyimide, and to achieve an appropriate linear expansion coefficient characteristic, an appropriate molecular design is necessary.

Polyimide made of acid dianhydride and diamine with high rigidity has been proposed as a polyimide exhibiting low linear expansion characteristics, but the polymer is in a high temperature region (300 to 500 ° C) near the glass transition temperature. When it has a high linear expansion property or the rigidity of the polymer skeleton is too high, it often impairs the strength and flexibility of the film, etc. (Patent Document 1, Non-Patent Document 1), and it is not known to satisfy the requirements to a high degree. .

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-202729

[Non-patent literature]

[Non-Patent Document 1] Journal of Applied Polymer Science, Vol. 62, 2303-2310 (1996)

Accordingly, it is still required to be able to manufacture replaceable glass as a display Resin film for polyimide-based display substrates with high heat resistance, moderate coefficient of linear expansion, and high tensile strength for substrate materials for appliances.

The present invention has been made in view of the above circumstances, and its object is Provided is a resin composition for a display substrate that can form a resin film for a display device substrate having high heat resistance, a moderate coefficient of linear expansion, and high tensile strength.

In particular, it is an object of the present invention to provide a Applicable acid dianhydride and diamine as main components can form heat resistance, moderate flexibility, and moderate coefficient of linear expansion that can withstand the manufacturing process of displays, especially moderate linear expansion coefficients around 400-500 ° C The resin composition for a display substrate of a resin film.

Here, the term "moderate flexibility" refers to a high degree of flexibility that the resin film has self-supporting properties and is not cracked even when bent at an angle of 90 ° or in the vicinity thereof.

The present inventors have repeatedly repeated the results of the positive review, and unexpectedly found that by using 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), p-phenylenediamine (p-PDA), and 4,4 "-diamino-p-terphenyl (DATP) -derived resin composition containing specific polyamic acid to obtain heat resistance, moderate flexibility, and moderate coefficient of linear expansion required for display substrates Resin film. The obtained resin film has high tensile strength (excellent self-supporting property). From these characteristics, it can be known that it is an excellent substrate material for display with characteristics that replace glass. Furthermore, the inventors and others also hair In addition to the above-mentioned components, these effects are further enhanced by using a polyamidic acid that further utilizes 2- (3-aminophenyl) -5-aminobenzimidazole (APAB). The present invention has been completed based on these findings.

Therefore, the present invention relates to the following inventions.

<1> A resin composition for a display substrate, comprising a polyamic acid containing a structural unit represented by the following formula (1) and having a weight average molecular weight of 10,000 or more, and an organic solvent,

[In the formula, X ¹ represents a tetravalent aromatic group of the following formula (3), Y ¹ represents a group of the following formula (P), and n represents the number of repeating units;

[In the formula, R represents F, Cl, an alkyl group having 1 to 3 carbon atoms, or phenyl group, m represents an integer of 0 to 4, and r represents an integer of 1 to 3]].

<2> In the aforementioned <1>, the structural unit represented by the formula (1) should preferably have a random or block copolymer structure of two or more repeating units of the formula (1).

<3> The aforementioned <1> should preferably include a polyamic acid containing a structural unit represented by the following formula (1-1) and formula (1-2) and having a weight average molecular weight of 10,000 or more, and an organic solvent,

[Wherein X ¹ represents a tetravalent aromatic group of the aforementioned formula (3), Y ² represents a group represented by the following formula (P1) or (P2), and Y ³ represents a group represented by the following formula (P3), and n ¹ and n ² represent the number of each repeating unit;

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ^5, and R ⁶ may be the same or different. They represent F, Cl, an alkyl group having 1 to 3 carbon atoms, or a phenyl group, m1, m2, and m3. , M4, m5, and m6 can be the same or different and represent integers from 0 to 4)].

<4> In any one of the aforementioned <1> to <3>, the polyamic acid preferably further contains a structural unit represented by the following formula (2),

[In the formula, X ¹ represents a tetravalent aromatic group of the aforementioned formula (3), Y ⁴ represents a group represented by the following formula (P4), and n ³ represents the number of repeating units;

(In the formula, R ⁷ and R ⁸ may be the same or different. They represent F, Cl, an alkyl group having 1 to 3 carbon atoms, or a phenyl group. R ′ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or benzene Base, and l and m may be the same or different, and represent an integer of 0 to 4)]. <5> In the aforementioned <3> or <4>, n ¹ and n ² should satisfy the condition of n ¹ / n ² = 1.7 ~ 20.

<6> In the aforementioned <4>, the aforementioned n ¹ , n ² and n ³ should satisfy n ³ / (n ¹ + n ² + n ³ ) ≦ 0.2.

<7> The aforementioned polyamic acid preferably contains at least 60 mol% of a structural unit represented by formula (1), or a structural unit represented by formula (1-1) and formula (1-2).

<8> A resin film for a display substrate, which is produced using the resin composition for a display substrate according to any one of <1> to <7>.

<9> An image display device including the resin film for a display substrate of <8>.

<10> A method for producing a resin film for a display substrate, characterized in that the resin composition for a display substrate according to any one of <1> to <7> is used. In a preferred aspect, the method for manufacturing a resin film for a display substrate includes the steps of applying the resin composition for a display substrate to a substrate and heating the substrate.

<11> A method for manufacturing an image display device, characterized in that the resin film for a display substrate according to <8> is used.

The resin composition for a display substrate of the present invention can be widely used. The usable acid dianhydride and the widely usable diamine are manufactured as main components. By using the usable acid dianhydride, the wet process can be used to obtain a large area with good reproducibility, high heat resistance, moderate flexibility, and a moderate linear expansion coefficient. Especially the resin film with moderate linear expansion coefficient near 400 ~ 500 ℃.

Therefore, by using the resin composition for a display substrate of the present invention, not only can the weight and size of the display be reduced, but also the price of the display can be reduced by reducing the raw material cost or improving the manufacturing efficiency.

Hereinafter, the present invention will be described in detail.

[Resin composition for display substrate]

As described above, the resin composition for a display substrate of the present invention includes a polyamic acid containing a structural unit represented by the formula (1) and having a weight average molecular weight of 10,000 or more, and an organic solvent.

As described above, in the formula (1), X ¹ represents a tetravalent aromatic group of the formula (3), and Y ¹ represents a group represented by the formula (P).

In the formula (P), R represents F, Cl or an alkyl group having 1 to 3 carbon atoms or a phenyl group, and preferably represents F or Cl. Similarly, in the aforementioned formula (P), m represents an integer of 0 to 4, preferably 0 to 2, more preferably 0 to 1, and most preferably 0. In the aforementioned formula (P), r represents an integer of 1 to 3.

The alkyl group having 1 to 3 carbon atoms includes methyl, ethyl, n-propyl, and Isopropyl, preferably an alkyl group having 1 to 3 carbon atoms is methyl, and more preferably methyl.

In formula (1), n represents the number of repeating units and is positive The integer is determined based on the weight average molecular weight of the polyamic acid used in the present invention.

A repeating order represented by formula (1) used in the present invention The weight average molecular weight of the polyamine must be 10,000 or more, preferably 15,000 or more, more preferably 20,000 or more, and still more preferably 30,000 or more. On the other hand, the upper limit of the weight average molecular weight of the polyamic acid used in the present invention is usually 2,000,000 or less. However, it is considered that high viscosity and high reproducibility can be obtained by suppressing the viscosity of the resin composition (paint) or the reproducibility. In the case of a resin film or the like, it is preferably 1,000,000 or less, and more preferably 200,000 or less.

The polyamidic acid used in the present invention contains at least 50 mole%, The repeating unit represented by formula (1) is preferably at least 60 mol%, more preferably at least 70 mol%, still more preferably at least 80 mol%, and even more preferably at least 90 mol%. By using the polyamic acid in this amount, a resin film having characteristics suitable for a display substrate can be obtained with good reproducibility.

According to a preferred aspect of the present invention, the polyamino acid is The copolymer formed by the repeating units represented by the formula (1), that is, the polymer containing the repeating units at 100 mol%. At this time, the structural unit represented by the formula (1) in the polyamic acid is not composed of only one of the repeating units represented by the formula (1), but preferably has two or more of the formula (1) Random or block copolymer construction of repeating units. The type of the repeating unit of the formula (1) that can be used is preferably 2 to 4 types, more preferably 2 to 3 types.

According to a preferred aspect of the present invention, the display base of the present invention As described above, the resin composition for a board includes a polyamic acid containing a polyamic acid having a structural unit represented by the formula (1-1) and the formula (1-2) and having a weight average molecular weight of 10,000 or more, and Organic solvent.

Further, as described above, in the formulae (1-1) and (1-2), X ¹ represents a tetravalent aromatic group of the aforementioned formula (3), and Y ² represents one represented by the aforementioned formula (P1) or (P2) The base is preferably a base represented by the formula (P1), and Y ³ is a base represented by the aforementioned formula (P3).

In formula (P1), formula (P2), and formula (P3), R ¹ , R ² , R ³ , R ⁴ , R ^5, and R ⁶ may be the same or different, indicating F, Cl, and carbon number 1 to 3. The alkyl group or the phenyl group preferably represents F or Cl.

Similarly, in the aforementioned formula (P), m1, m2, m3, m4, m5, and m6 may be the same or different. They represent integers of 0 to 4, preferably 0 to 2, and more preferably 0 to 1, and most Good means 0.

In the formulas (1-1) and (1-2), n ¹ and n ² represent the number of each repeating unit, and the condition of n ¹ / n ² = 1.7 to 20 is satisfied. Here, the lower limit value of the aforementioned numerical range of n ¹ / n ² is preferably 2.1, more preferably 2.2, and even more preferably 2.3. On the other hand, the upper limit of the numerical range of n ¹ / n ² is preferably 19, and more preferably 18.

When a resin film having a moderate linear expansion coefficient, heat resistance, and flexibility (especially tensile strength) is obtained with good reproducibility, n ¹ / n ² preferably satisfies 2.1 to 7.5, more preferably 2.1 to 6.8, and more Best meets 3.2 ~ 6.0, and even better meets 3.2 ~ 5.1.

The polyamidic acid used in the present invention contains at least 50 mole%, Preferably at least 60 mol%, more preferably at least 70 mol%, still more preferably at least 80 mol%, and even more preferably at least 90 mol% is expressed by the formula (1-1) and (1-2) Repeating units. By using the polyamic acid in this amount, a resin film having characteristics suitable for a display substrate can be obtained with good reproducibility.

According to the best aspect of the present invention, polyamine The copolymer formed by the repeating units represented by the formula (1-1) and the formula (1-2), that is, a polymer containing these repeating units at 100 mol%.

The weight average molecular weight of the polyamidic acid used in the present invention must be It is 10,000 or more, preferably 15,000 or more, more preferably 20,000 or more, and still more preferably 30,000 or more. On the other hand, the upper limit of the weight average molecular weight of the polyamic acid used in the present invention is usually 2,000,000 or less. However, it is considered that a resin composition (paint) can be suppressed to have an excessively high viscosity or a good reproducibility to obtain a high flexibility In the case of a resin film or the like, it is preferably 1,000,000 or less, and more preferably 200,000 or less.

According to a better aspect of the present invention, the polymer used in the present invention The amino acid may further contain a structural unit represented by the formula (2).

As described above, in the formula (2), X ¹ represents the tetravalent aromatic group of the aforementioned formula (3), Y ⁴ represents the group represented by the aforementioned formula (P4), and n ³ represents the number of each repeating unit.

In formula (P4), R ⁷ and R ⁸ may be the same or different, and represent F, Cl, an alkyl group having 1 to 3 carbon atoms, or a phenyl group. R ⁷ preferably represents F or Cl. R ⁸ preferably represents F or Cl.

R 'represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom.

In addition, l and m may be the same or different, and represent integers of 0 to 4, preferably 0 to 2, more preferably 0 to 1, and most preferably 0.

In addition to the structural unit represented by formula (1), when the structural unit represented by formula (2) is included, n and n ³ preferably satisfy n ³ / (n + n ³ ) ≦ 0.2, and more preferably satisfy n ³ / ( n + n ³ ) ≦ 0.1, and more preferably n ³ / (n + n ³ ) ≦ 0.05. Within this range, it is advantageous in terms of reproducibility to obtain a resin film having a moderate coefficient of linear expansion, heat resistance, and flexibility (especially tensile strength).

In addition to the structural units represented by formulas (1-1) and (1-2), when the structural units represented by formula (2) are included, n ¹ , n ² , and n ³ represent the number of each repeating unit, preferably Satisfies n ³ / (n ¹ + n ² + n ³ ) ≦ 0.2, more preferably satisfies n ³ / (n ¹ + n ² + n ³ ) ≦ 0.1, and more satisfies n ³ / (n ¹ + n ² + n ³ ) ≦ 0.05. Within this range, it is advantageous in terms of reproducibility to obtain a resin film having a moderate coefficient of linear expansion, heat resistance, and flexibility (especially tensile strength).

The polyamic acid used in the present invention may contain other structural units (repeated units) in addition to the structural units represented by formula (1) or the structural units represented by formulas (1-1) and (1-2). ). The content of the other structural units must be less than 50 mole%, preferably less than 40 mole%, more preferably less than 30 mole%, more preferably less than 20 mole%, and even more preferably less than 10 mole%. ear%.

The other structural units are listed as o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2-methyl-1,4-phenylenediamine, 5-methyl-1,3-benzenediamine Amine, 4-methyl-1,3-phenylenediamine, 2- (trifluoromethyl) -1,4-phenylenediamine, 2- (trifluoromethyl) -1,3-phenylenediamine and 4- (trifluoromethyl) -1,3-phenylenediamine, benzidine, 2,2'-dimethylbenzidine, 3, 3'-dimethylbenzidine, 2,3'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) benzidine, 3,3'-bis (trifluoromethyl) benzidine, 2,3'-bis (trifluoromethyl) benzidine, 4,4'-diphenyl ether, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-diamine Benzidine, aniline, 5-amino-2- (3-aminophenyl) -1H-benzimidazole, 9,9-bis (4-aminophenyl) fluorene diamine, and pyromellitic Carboxylic anhydride (PMDA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3 ', 4,4'-benzophenone tetra Structures derived from acid dianhydride of carboxylic anhydride.

According to a preferred aspect of the present invention, the polymer used in the present invention Amidine can be obtained by using 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) (formula (4)) as an acid dianhydride and p-phenylenediamine as a diamine ( pPDA) (formula (5)) and 4,4 "-diamino-p-bitriphenyl (DATP) (formula (6)).

In the above reaction, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (pPDA) and 4,4 "-diamine-p-bitriphenyl ( The feed ratio (mole ratio) of the diamine formed by DATP) can be appropriately set in consideration of the molecular weight or structural unit ratio of the desired polyamic acid, but it can be generally set as the BPDA of the acid anhydride component relative to the amine component 1. About 0.7 to 1.3, preferably about 0.8 to 1.2.

On the other hand, the diamine feed pPDA DATP was the time when the ratio of the mass of DATP (m ²⁾ is set to 1, was pPDA of mass (m ¹⁾ typically may be about 1.7 to 20, preferably 2.1 to 20, more preferably 2.2 to 20, more preferably 2.3 to 19, and even more preferably 2.3 to 18. That is, m ¹ and m ² are usually m ¹ / m ² = 1.7 to 20, preferably 2.1 to 20, more preferably 2.2 to 20, still more preferably 2.3 to 19, and even more preferably 2.3 to 18.

According to a better aspect of the present invention, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) as an acid dianhydride, and pPDA) and 4,4 "-diamino-p-bitriphenyl (DATP) and other 2- (3-aminophenyl) -5-aminobenzimidazole (APAB) (formula (7)) The reaction was obtained.

In the above reaction, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), p-phenylenediamine (pPDA) and 4,4 "-diamine-p-bitriphenyl (DATP) and 2- (3-aminophenyl) -5-aminobenzimidazole (APAB) feed ratio of diamine (mole ratio) can consider the molecular weight of the desired polyamic acid or The ratio of the structural unit is appropriately set, but the BPDA of the acid anhydride component can be generally set to about 0.7 to 1.3, and preferably about 0.8 to 1.2, with respect to the amine component 1.

On the other hand, the feed ratio of pPDA, DATP, and APAB of the diamine is when the total of pPDA (m ¹ ) and DATP (m ² ) and APAB (m ³ ) is set to 1. The physical mass (m ³ ) of APAB is preferably 0.2 or less, more preferably 0.1 or less, and still more preferably 0.05 or less. That is, m ¹ and m ² and m ³ preferably satisfy m ³ / (m ¹ + m ² + m ³ ) ≦ 0.2, and more preferably satisfy m ³ / (m ¹ + m ² + m ³ ) ≦ 0.1, and More preferably, m ³ / (m ¹ + m ² + m ³ ) ≦ 0.05 is satisfied.

The above reaction is preferably carried out in a solvent. When a solvent is used, as long as the type does not adversely affect the reaction, various solvents can be used.

Specific examples include m-cresol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethyl Propamide, 3-propoxy-N, N-dimethylpropanamide, 3-isopropoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-di Methylpropionamine, 3-second butoxy-N, N-dimethylpropionamine, 3-third butoxy-N, N-dimethylpropionamine, γ-butyrolactone, etc. Protic solvents Wait. These can be used individually or in combination of 2 or more types.

The reaction temperature ranges from the melting point to the boiling point of the solvent used. It can be set appropriately within the range, usually about 0 to 100 ° C, but in order to prevent the polyimide of the obtained polyamic acid and maintain a high content of the polyamic acid unit, it is preferably about 0 to 70 ° C, more It is preferably about 0 to 60 ° C, and more preferably about 0 to 50 ° C.

The reaction time cannot be generalized because it is related to the reaction temperature or the reactivity of the raw materials, but it is usually about 1 to 100 hours.

By the method described above, a reaction solution containing the target polyamic acid can be obtained.

In the present invention, after filtering the reaction solution, the filtering solution is usually used as it is, or it is diluted or concentrated to be used as a resin composition (paint) for a display substrate. This not only reduces the inclusion of impurities that cause deterioration of the heat resistance, flexibility, or coefficient of linear expansion coefficient of the obtained resin film, but also effectively obtains a composition.

The solvent used for dilution or concentration is not particularly limited, and examples include the same as the specific examples of the reaction solvent for the reaction described above, and these may be used alone or in combination of two or more.

Among these, when a resin film having high flatness is obtained with good reproducibility, the solvent used is preferably N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl- 2-pyrrolidone, 1,3-dimethyl-2-imidazolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone.

In addition, in the present invention, the reaction solution may be subjected to a post-treatment according to a conventional method to isolate the polyamic acid, and then polymerize the isolated solution. A paint obtained by dissolving or dispersing arsenic acid in a solvent is used as a resin composition for a display substrate. In this case, when a thin film having a high flatness is obtained with good reproducibility, it is preferable that the polyamic acid is dissolved in a solvent. The solvent used in the dissolution or dispersion is not particularly limited. For example, the solvent is the same as the specific example of the reaction solvent of the above reaction, and they can be used alone or in combination of two or more kinds.

The concentration of polyamic acid relative to the total mass of the paint is considered The thickness of the produced film or the viscosity of the paint is appropriately set, but it is usually about 0.5 to 30% by mass, preferably about 5 to 25% by mass.

In addition, the viscosity of the paint is also based on the thickness of the film produced. If the degree is appropriately set, especially when a resin film having a thickness of about 5 to 50 μm is obtained for good reproducibility, it is usually 500 to 50,000 mPa at 25 ° C. s, preferably 1,000 ~ 20,000mPa. s around.

Here, the viscosity of the paint can be measured using a commercially available viscometer for measuring liquid viscosity, referring to, for example, the procedure described in JIS K7117-2 under the conditions of a paint temperature of 25 ° C. Preferably, the viscometer is a cone plate type rotary viscometer, and the same type of viscometer uses 1 ° 34 '× R24 as a standard cone rotor, and is measured at a paint temperature of 25 ° C. Examples of the rotational viscosity meter include TVE-25H manufactured by Toki Sangyo Co., Ltd.

The resin composition for a display substrate of the present invention described above is coated on a substrate and heated to obtain a resin film made of polyimide having high heat resistance, moderate flexibility, and a moderate linear expansion coefficient.

Examples of the substrate (base material) include plastic (polycarbonate) (Ester, polymethacrylate, polystyrene, polyester, polyolefin, epoxy resin, melamine, triethyl cellulose, ABS, AS, norbornene-based resin, etc.), metal (silicon wafer, etc.) , Wood, paper, glass, slate, etc.

The coating method is not particularly limited, and examples thereof include casting. Method, spin coating method, blade coating method, dip coating method, roll coating method, bar coating method, die coating method, inkjet method, printing method (convex plate, gravure, lithography, screen printing, etc.) Wait.

In addition, as a resin composition for a display substrate of the present invention, The method of polyimide-imidization contained in the material includes heating-imidization that directly heats the resin composition coated on the substrate, and adding a catalyst to the resin composition and heating it. Catalyst 醯 imidization.

Polyamine catalysts and imidization catalysts are added to the catalyst In the resin composition of the invention, a catalyst is added to the resin composition while stirring to adjust the resin composition, and then the resin composition is applied to a substrate and heated to obtain a resin film. The amount of catalyst is 0.1 to 30 mol times, preferably 1 to 20 mol times. Furthermore, acetic anhydride or the like can be added to the catalyst-added resin composition as a dehydrating agent in an amount of 1 to 50 mol times of the amino acid group, preferably 3 to 30 mol times.

As the imidization catalyst, tertiary amine is preferably used. As tertiary amine Preferred are pyridine, substituted pyridines, imidazoles, substituted imidazoles, methylpyridine, quinoline, isoquinoline, and the like.

The heating temperature of hot 醯 imidization and catalyst 醯 It is preferably below 450 ° C. When the temperature exceeds 450 ° C, the obtained resin film becomes brittle, and a resin film suitable for a display substrate application may not be obtained.

In addition, when considering the heat resistance and linear expansion coefficient characteristics of the obtained resin film, it is preferable to heat the coated resin composition at 50 ° C to 100 ° C for 5 minutes to 2 hours, and then directly increase the heating temperature stepwise, and finally at Heating for more than 375 ℃ ~ 450 ℃ for 30 minutes ~ 4 hours.

In particular, the coated resin composition is preferably heated at 50 ° C to 100 ° C for 5 minutes to 2 hours, and then heated at over 100 ° C to 200 ° C for 5 minutes to 2 hours, and then heated at over 200 ° C to 375 ° C for 5 minutes. Minutes to 2 hours, and finally heated at over 375 ° C to 450 ° C for 30 minutes to 4 hours.

Examples of the apparatus used for heating include a hot plate and an oven. The heating environment may be under air or under an inert gas, and may be under normal pressure or under reduced pressure.

The thickness of the resin film is particularly useful as a flexible display. The substrate is usually about 1 to 60 μm, preferably about 5 to 50 μm, and the thickness of the coating film before heating is adjusted to form a resin film of a desired thickness.

Since the resin film described above satisfies the requirements of flexibility, Various conditions are necessary for the base film of the display substrate, so it is most suitable to use the base film as a flexible display substrate.

[Example]

The following examples illustrate the present invention more specifically, but the present invention is not limited to the following examples.

[1] Abbreviations used in the examples

The abbreviations used in this embodiment are as follows.

<Solvents>

NMP: N-methyl-2-pyrrolidone

<Amines>

p-PDA: p-phenylenediamine

APAB: 2- (3-aminophenyl) -5-aminobenzimidazole

DATP: 4,4 "-diamine-p-terphenyl

BABP: bis (4-aminophenoxy) benzophenone

DABA: N- (4-aminophenyl) -4-aminobenzidine

<Acid dianhydride>

BPDA: 3,3 ’, 4,4’-biphenyltetracarboxylic acid diamine

TAHQ: p-phenylene bis (trimellitic acid monoester anhydride)

PMDA: pyromellitic dianhydride

NTCDA: naphthalene-1,4,5,8-tetracarboxylic dianhydride

[2] Measurement of number average molecular weight and weight average molecular weight

The weight-average molecular weight of the polymer (hereinafter referred to as Mw) and molecular weight distribution (Mw / Mn) are based on a GPC device (Shodex (trademark) column KF803L and KF805L) manufactured by JASCO Corporation, with a flow rate of 1ml / min. Methylformamide was used as a dissolution solvent, and the column temperature was measured at 50 ° C. In addition, Mw is a polystyrene conversion value. In addition, Mn is an abbreviation for number average molecular weight.

[3] Preparation of resin composition for display substrate (synthesis of polyamic acid) <Example 1: Synthesis of polyamidic acid (P1)>

BPDA (98) // p-PDA (90) / DATP (5) / APAB (5)

Dissolve 17.8g (0.165 moles) of p-PDA and 2.38g (0.009 moles) of DATP and 2.05g (0.009 moles) of APABI in 420g of NMP, add 52.8g (0.179 moles) of BPDA, and then add NMP again 5 g was reacted at 23 ° C. for 24 hours under a nitrogen atmosphere.

The weight average molecular weight (Mw) of the obtained polymer was 63,800, and the molecular weight distribution (Mw / Mn) was 11.3. This solution was used as a resin composition for a display substrate.

<Example 2: Synthesis of polyamidic acid (P2)>

BPDA (98) // p-PDA (70) / DATP (25) / APAB (5)

Dissolve 12.9g (0.119 mole) of p-PDA, 11.1g (0.043 mole) of DATP and 1.90g (0.009 mole) of APABI in 420g of NMP, and add 49.1g (0.167 mole) of BPDA, and then add NMP again 5 g was reacted at 23 ° C. for 24 hours under a nitrogen atmosphere.

The Mw of the obtained polymer was 65500, and the molecular weight distribution (Mw / Mn) was 12.8. This solution was used as a resin composition for a display substrate.

<Example 3: Synthesis of polyamidic acid (P3)> BPDA (98) // p-PDA (70) / DATP (30)

Dissolve 12.8g (0.119 moles) of p-PDA and 13.2g (0.051 moles) of DATP in 420g of NMP, and add 48.9g (0.167 moles) of BPDA at the same time, and then add 5g of NMP again under nitrogen atmosphere at 23 The reaction was carried out at 24 ° C for 24 hours.

The obtained polymer had a Mw of 66,300 and a molecular weight distribution (Mw / Mn) of 12.9. This solution was used as a resin composition for a display substrate.

<Comparative Example 1: Synthesis of Polyamic Acid (HP1)> TAHQ // p-PDA

2.33 g (0.022 mol) of p-PDA was dissolved in 700 g of NMP, TAHQ 9.67 g (0.021 mol) was added, 88 g of NMP was added again, and the reaction was performed at 23 ° C. for 24 hours under a nitrogen atmosphere.

The Mw of the obtained polymer was 75200, and the molecular weight distribution (Mw / Mn) was 2.6. This solution was used as a resin composition for a display substrate.

<Comparative Example 2: Synthesis of Polyamic Acid (HP2)> BPDA // DATP

7.11 g (0.027 mole) of DATP and 7.88 g (0.027 mole) of p-PDA were dissolved in 85 g of NMP, and 7.88 g (0.027 mole) of BPDA was added, and then reacted at 23 ° C. for 24 hours under a nitrogen atmosphere.

The Mw of the obtained polymer was 70,700, and the molecular weight distribution (Mw / Mn) was 9.7. This solution was used as a resin composition for a display substrate.

<Comparative Example 3: Synthesis of Polyamic Acid (HP3)> BPDA // p-PDA

4.09 g (0.004 mol) of p-PDA was dissolved in 85 g of NMP, and 10.9 g (0.037 mol) of BPDA was added, and then reacted at 23 ° C. for 24 hours under a nitrogen atmosphere.

The Mw of the obtained polymer was 65,000, and the molecular weight distribution (Mw / Mn) was 2.3. This solution was used as a resin composition for a display substrate.

<Comparative Example 4: Synthesis of Polyamic Acid (HP4)> PMDA // p-PDA

8.23 g (0.031 mol) of p-PDA was dissolved in 85 g of NMP, and 6.76 g (0.031 mol) of PMDA was added, and then reacted at 23 ° C. for 24 hours under a nitrogen atmosphere.

The Mw of the obtained polymer was 45,000, and the molecular weight distribution (Mw / Mn) was 10.6. This solution was used as a resin composition for a display substrate.

<Comparative Example 5: Synthesis of Polyamic Acid (HP5)> BPDA / NTCDA // p-PDA / DBAB / BABP

P-PDA 3.07g (0.029 moles), DABA 0.27g (0.001 moles) and BABP 0.12g (0.0003 moles) were dissolved in NMP 88g, BPDA 7.73g (0.026 moles) was added, and NTCDA 0.80g ( 0.003 mole), and then reacted at 23 ° C for 24 hours under a nitrogen atmosphere.

The obtained polymer had an Mw of 57,000 and a molecular weight distribution (Mw / Mn) of 9.3. This solution was used as a resin composition for a display substrate.

[3] Production and evaluation of resin film for display substrate (production and evaluation of polyimide film) <Film thickness before hardening>

Use a bar coater to apply the separately prepared polyamic acid on a 100 mm × 100 mm glass substrate, and heat at a temperature of 10 degrees / minute at 120 degrees for 10 minutes, 300 degrees for 60 minutes, and 450 degrees for 60 minutes. The film was obtained by baking in an oven.

The film thickness of the obtained coating film was measured using a contact-type film thickness measuring device (Dektak 3ST manufactured by ULVAC Corporation).

The obtained results are described in Table 1.

Subsequently, the glass substrates were placed one by one in 70-degree pure water in a 1 L beaker to peel off the film.

<Linear expansion coefficient>

A short strip of 20 mm × 5 mm was prepared from the film obtained above, and the linear expansion coefficient from 50 to 500 degrees was measured using TMA-4000SA (manufactured by Bruker AXS Co., Ltd.).

The obtained results are described in Table 1.

<Weight reduction>

A strip of 20 mm × 3 mm was produced from the film obtained above, and a weight reduction from 50 to 600 degrees was measured using TGA-DTA-2000SR (manufactured by Bruker AXS Co., Ltd.), and a weight reduction of 5% was confirmed.

The obtained results are described in Table 1.

In addition, when the weight is not reduced by 5% at 600 degrees, it is described as "600 degrees>" in the table.

The results show that the resin film of the present invention has excellent heat resistance.

<Self-supporting>

The obtained film was bent at 90 degrees or more, and the self-supporting property was evaluated according to the following evaluation criteria.

The obtained results are described in Table 1.

From the results, it can be seen that the resin film of the present invention has good flexibility, and has a high degree of flexibility that does not crack even when bent to an angle of 90 degrees or close to 90 degrees.

[Evaluation criteria]

○: Self-supporting, does not break even when bent to 90 degrees

△: Self-supporting, but bent and broken

×: No self-supporting

××: Decomposed on the substrate

Claims (10)

A resin composition for a display substrate, comprising a polyamic acid containing a structural unit represented by the following formula (1-1) and formula (1-2) and having a weight average molecular weight of 10,000 or more, and an organic solvent, [Wherein X ¹ represents a tetravalent aromatic group of the following formula (3), Y ² represents a group represented by the following formula (P1) or (P2), and Y ³ represents a group represented by the following formula (P3), And n ¹ and n ² represent the number of each repeating unit; (In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ may be the same or different. They represent F, Cl, an alkyl or phenyl group having 1 to 3 carbon atoms, m1, m2, m3, m4, m5, and m6 can be the same or different, and represent integers from 0 to 4)]. The resin composition for a display substrate according to claim 1, wherein the polyamino acid has a random or block copolymer structure having a structural unit represented by the formula (1-1) and the formula (1-2). If the resin composition for a display substrate of claim 1 or 2, wherein the polyamic acid further contains a structural unit represented by the following formula (2), [In the formula, X ¹ represents a tetravalent aromatic group of the aforementioned formula (3), Y ⁴ represents a group represented by the following formula (P4), and n ³ represents the number of repeating units; (In the formula, R ⁷ and R ⁸ may be the same or different, and represent F, Cl, an alkyl or phenyl group having 1 to 3 carbon atoms, and R ′ represents a hydrogen atom, an alkyl or phenyl group having 1 to 3 carbon atoms, And l and m may be the same or different, and represent an integer of 0 to 4)]. For example, the resin composition for a display substrate of claim 1, wherein n ¹ and n ² satisfy a condition of n ¹ / n ² = 1.7 to 20. The resin composition for a display substrate according to claim 3, wherein n ¹ , n ² and n ³ satisfy n ³ / (n ¹ + n ² + n ³ ) ≦ 0.2. For example, the resin composition for a display substrate according to claim 1 or 2, wherein the aforementioned polyamic acid contains at least 60 mol% of a structural unit represented by the formula (1-1) and the formula (1-2). A resin film for a display substrate, which is produced using the resin composition for a display substrate according to any one of claims 1 to 6. An image display device includes the resin film for a display substrate according to claim 7. A method for manufacturing a resin film for a display substrate, which is characterized by using the resin composition for a display substrate according to any one of claims 1 to 6. A method for manufacturing an image display device is characterized by using a resin film for a display substrate as claimed in claim 7.