CN108026274B

CN108026274B - Polybenzoxazole and use thereof

Info

Publication number: CN108026274B
Application number: CN201680053831.2A
Authority: CN
Inventors: 江原和也; 进藤和也
Original assignee: Nissan Chemical Corp
Current assignee: Nissan Chemical Corp
Priority date: 2015-09-18
Filing date: 2016-09-13
Publication date: 2020-11-17
Anticipated expiration: 2036-09-13
Also published as: TW201723028A; CN108026274A; KR102581615B1; JP6888549B2; JPWO2017047561A1; WO2017047561A1; TWI709594B; KR20180055820A

Abstract

The invention provides a polymer which gives a film having good water vapor barrier properties even without using an inorganic component, and use thereof. A polybenzoxazole characterized by being represented by formula (2). (in the formula, R¹～R¹³Independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, or an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms, which may be substituted with a halogen atom, and n represents an integer of 2 or more. )

Description

Polybenzoxazole and use thereof

Technical Field

The present invention relates to polybenzoxazole and use thereof.

Background

In recent years, with the development of electronic devices, weight reduction and miniaturization thereof have been achieved. In assembling the glass substrate, it is attempted to use a lighter and more flexible resin substrate instead of the glass substrate conventionally used.

However, resin substrates are often inferior to glass substrates in gas barrier properties such as water vapor. Therefore, for practical use of a resin substrate in an electronic device, it is one of the problems to be solved to ensure gas barrier properties against water vapor and the like that enter the inside of an element and adversely affect an electronic circuit, a component of the device, and the like.

As means for solving such problems, for example, a technique of using a composition containing polyimide and an organic layered silicate and a technique of forming a silicon oxide thin film as a barrier layer on a polyimide film surface have been reported (see patent documents 1 and 2).

However, in these techniques, since a polyimide resin which is poor in gas barrier property is used as a main component, in order to improve the gas barrier property, an inorganic component other than the resin component is necessary, and the production process is complicated, and the production cost is also disadvantageous.

Therefore, it is desired to develop a film which contains a resin having a good gas barrier property as a main component and can exhibit a sufficient gas barrier property even without containing other inorganic components.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-245460

Patent document 2: japanese patent laid-open No. 2012 and 107178

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polymer which gives a film having excellent water vapor barrier properties without using an inorganic component alone, and use thereof.

Means for solving the problems

The present inventors have made extensive studies to achieve the above object, and as a result, have found that: polybenzoxazole having a predetermined structure gives a film excellent in water vapor barrier properties even without using an inorganic component, and the present invention has been completed.

Namely, the present invention provides:

1. a polybenzoxazole precursor characterized by being represented by the formula (1),

[ solution 1]

(in the formula, R¹～R¹³Independently represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, or an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or an alkynyl group having 2 to 20 carbon atoms which may be substituted with a halogen atomAn aryl group having 6 to 20 carbon atoms or a heteroaryl group having 2 to 20 carbon atoms, and n represents an integer of 2 or more. )

2.1 Polybenzoxazole precursors, wherein R is¹～R¹³Is a hydrogen atom, and is a hydrogen atom,

3. a polybenzoxazole represented by the formula (2),

[ solution 2]

(in the formula, R¹～R¹³Independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, or an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms, which may be substituted with a halogen atom, and n represents an integer of 2 or more. )

4.3 Polybenzoxazoles wherein R is¹～R¹³Is a hydrogen atom, and is a hydrogen atom,

5. a film-forming composition comprising a polybenzoxazole precursor of 1 or 2 and an organic solvent,

6. a film-forming composition comprising 3 or 4 polybenzoxazole and an organic solvent,

7. a film comprising 3 or 4 polybenzoxazole,

8. a process for producing a thin film, which comprises applying the film-forming composition of claim 5 onto a substrate, heating the composition to evaporate the organic solvent and to close the ring of the polybenzoxazole precursor,

9. a process for producing a thin film, which comprises applying the composition for film formation of claim 6 on a substrate, evaporating the organic solvent,

10. an electronic device having a thin film of 7 as a substrate,

11.10, which is an organic electroluminescent element,

12.1A method for producing a polybenzoxazole precursor, characterized in that the polybenzoxazole precursor represented by the formula (3)

[ solution 3]

(in the formula, R¹～R⁷Represents the same meaning as above, X represents a halogen atom, a hydroxyl group, a phenoxy group, a2, 4, 5-trichlorophenoxy group, a 1H- [1,2, 3]]Triazolyloxy [4,5-b ]]Pyridyl, 1H-benzo [ d ]][1,2,3]A triazolyloxy group, a2, 3-dihydro-2-thioxo-3-benzoxazolyl group or a 4, 6-dimethoxy-1, 3, 5-triazinyloxy group. )

A dicarboxylic acid compound represented by the formula (4)

[ solution 4]

(in the formula, R⁸～R¹³The same meanings as described above are indicated. )

The diamine compound shown is reacted with a diamine compound,

13.3A process for producing a polybenzoxazole, which comprises heating a polybenzoxazole precursor represented by the formula (1) to close the ring,

[ solution 5]

(in the formula, R¹～R¹³The same meanings as described above are indicated. ).

ADVANTAGEOUS EFFECTS OF INVENTION

By using the polybenzoxazole of the present invention, a film having excellent water vapor barrier properties can be produced without using an inorganic component or the like.

In addition, the polybenzoxazole of the present invention has heat resistance that can withstand a TFT manufacturing process.

The film containing the polybenzoxazole of the present invention having such characteristics can be suitably used as a member requiring water vapor barrier properties and heat resistance, such as an (electrode) substrate of an electronic device.

Drawings

FIG. 1 shows IR spectra of a precursor [3] and polybenzoxazole [4 ].

Detailed Description

The present invention will be described in more detail below.

The polybenzoxazole according to the present invention is represented by formula (2), and can be obtained by ring-closing a polybenzoxazole precursor (poly-o-hydroxyamide) represented by formula (1).

[ solution 6]

[ solution 7]

In the formulae (1) and (2), R¹～R¹³Independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, or an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms, which may be substituted with a halogen atom, and n represents an integer of 2 or more.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like.

Examples of the alkyl group having 1 to 20 carbon atoms include straight-chain, branched-chain and cyclic alkyl groups, and examples thereof include straight-chain or branched-chain alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl and n-decyl groups; and C3-20 cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, bicyclobutyl, bicyclopentyl, bicyclohexyl, bicycloheptyl, bicyclooctyl, bicyclononyl, and bicyclodecyl.

Specific examples of the alkenyl group having 2 to 20 carbon atoms include vinyl, n-1-propenyl, n-2-propenyl, 1-methylvinyl, n-1-butenyl, n-2-butenyl, n-3-butenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 1-ethylvinyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, n-1-pentenyl, n-1-decenyl, n-1-eicosenyl and the like.

Specific examples of the alkynyl group having 2 to 20 carbon atoms include an ethynyl group, an n-1-propynyl group, an n-2-propynyl group, an n-1-butynyl group, an n-2-butynyl group, an n-3-butynyl group, a 1-methyl-2-propynyl group, an n-1-pentynyl group, an n-2-pentynyl group, an n-3-pentynyl group, an n-4-pentynyl group, a 1-methyl-n-butynyl group, a 2-methyl-n-butynyl group, a 3-methyl-n-butynyl group, a 1, 1-dimethyl-n-propynyl group, an n-1-hexynyl group, an n-1-decynyl group, an n-1-pentadecynyl group, an, N-1-eicosynyl, and the like.

Specific examples of the aryl group having 6 to 20 carbon atoms include phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, and 9-phenanthryl.

Specific examples of the heteroaryl group having 2 to 20 carbon atoms include oxygen-containing heteroaryl groups such as 2-thienyl, 3-thienyl, 2-furyl, 3-furyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl and 5-isoxazolyl, sulfur-containing heteroaryl groups such as 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isothiazolyl, 4-isothiazolyl and 5-isothiazolyl, 2-imidazolyl, 4-imidazolyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrazinyl, 3-pyrazinyl, 5-pyrazinyl, 6-pyrazinyl, 2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl, etc, 6-pyrimidinyl, 3-pyridazinyl, 4-pyridazinyl, 5-pyridazinyl, 6-pyridazinyl, 1,2, 3-triazin-4-yl, 1,2, 3-triazin-5-yl, 1,2, 4-triazin-3-yl, 1,2, 4-triazin-5-yl, 1,2, 4-triazin-6-yl, 1,3, 5-triazin-2-yl, 1,2,4, 5-tetrazin-3-yl, 1,2,3, 4-tetrazin-5-yl, 2-quinolinyl, 3-quinolinyl, 4-quinolinyl, 5-quinolinyl, 6-quinolinyl, 7-quinolinyl, 8-quinolinyl, 1-isoquinolinyl, And nitrogen-containing heteroaryl groups such as 3-isoquinolyl, 4-isoquinolyl, 5-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 8-isoquinolyl, 2-quinoxalinyl, 5-quinoxalinyl, 6-quinoxalinyl, 2-quinazolinyl, 4-quinazolinyl, 5-quinazolinyl, 6-quinazolinyl, 7-quinazolinyl, 8-quinazolinyl, 3-cinnolinyl, 4-cinnolinyl, 5-cinnolinyl, 6-cinnolinyl, 7-cinnolinyl, and 8-cinnolinyl.

Of these, R is preferred¹～R¹³A polybenzoxazole precursor represented by the following formula (5) and a polybenzoxazole represented by the following formula (6) all of which are hydrogen atoms.

[ solution 8]

The molecular weight of the polybenzoxazole of the present invention is not particularly limited, and if a film having excellent water vapor barrier properties and heat resistance is to be obtained, the weight average molecular weight is preferably 1000 to 200000, more preferably 1500 to 150000, and further preferably 2000 to 100000.

Accordingly, n in the above formulae (1), (2), (5) and (6) is an integer of 2 or more, and preferably an integer satisfying the above average molecular weight.

The polybenzoxazole precursor represented by formula (1) can be obtained by reacting a dicarboxylic acid compound represented by formula (3) with a diamine compound represented by formula (4).

[ solution 9]

In the formulae (3) and (4), R¹～R¹³Represents the same meaning as above, X represents a halogen atom, a hydroxyl group, a phenoxy group, a2, 4, 5-trichlorophenoxy group, a 1H- [1,2, 3]]Triazolyloxy [4,5-b ]]Pyridyl, 1H-benzo [ d ]][1,2,3]A triazolyloxy group, a2, 3-dihydro-2-thioxo-3-benzoxazolyl group or a 4, 6-dimethoxy-1, 3, 5-triazinyloxy group.

Examples of the alkoxy group having 1 to 5 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, and an n-pentoxy group, and examples of the halogen atom include the same halogen atoms as described above, in which case, a chlorine atom and a bromine atom are preferable, and a chlorine atom is more preferable.

The reaction is an amide formation reaction, and conventionally known amidation conditions can be used as the reaction conditions.

Specifically, each of the compounds represented by the formulae (3) and (4) may be reacted in an organic solvent at a predetermined temperature for a predetermined time.

The organic solvent is not particularly limited as long as it does not adversely affect the reaction, and examples thereof include amides such as N, N-dimethylformamide, N-dimethylacetamide, and N-methyl-2-pyrrolidone; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; esters such as gamma-butyrolactone, gamma-valerolactone, gamma-caprolactone, alpha-methyl-gamma-butyrolactone, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, etc.; aliphatic alcohols having 1 to 10 carbon atoms such as methanol, ethanol and propanol; phenols such as phenol and cresol; alcohols containing an aromatic group such as benzyl alcohol; glycols such as ethylene glycol and propylene glycol, glycol ethers such as ethylene glycol monomethyl ether and propylene glycol monomethyl ether; cyclic ethers such as dioxane and tetrahydrofuran; cyclic carbonates such as ethylene carbonate and propylene carbonate; aliphatic hydrocarbons such as pentane and hexane; aromatic hydrocarbons such as toluene and xylene; dimethyl sulfoxide and the like, and 1 kind thereof may be used alone, or 2 or more kinds thereof may be used in combination.

The reaction temperature is suitably determined in consideration of the melting point and boiling point of the solvent, the solubility of the raw material to be used, the reactivity, etc., and is usually in the range of-20 to 200. degreeCand, in the case where the compound represented by the formula (3) is a dicarboxylic acid (X: hydroxyl group), it is preferably about-20 to 50 ℃. In this case, a condensing agent such as diphenyl (2, 3-dihydro-2-thio-3-benzoyl) phosphonate (DBOP), N' -Dicyclohexylcarbodiimide (DCC) or 4- (4, 6-dimethoxy-1, 3, 5-triazin-2-yl) -4-methylmorpholinium (DMT-MM) and a base are preferably used in combination.

When the compound represented by the formula (3) is a dihalide of a dicarboxylic acid (X: a halogen atom), it is preferably about-20 to 100 ℃ and more preferably about-10 to 80 ℃, and the reaction is preferably carried out in the presence of a base in order to neutralize the hydrogen halide by-produced.

Examples of the base include amines such as triethylamine, pyridine and N, N-dimethyl-4-aminopyridine, and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.

The reaction time is about 0.1 to 72 hours.

The reaction ratio of each compound represented by the formula (3) and the formula (4) is preferably about 0.5 to 1.5 equivalents of the compound represented by the formula (3) relative to the amount of the substance (1 mole) of the diamine compound represented by the formula (4).

The solution containing the polybenzoxazole precursor represented by formula (1) obtained by the above method is heated to close the precursor ring, thereby obtaining a solution containing the polybenzoxazole represented by formula (2).

The heating is usually carried out by finally raising the temperature to about 200 to 500 ℃, and the following method is preferable: preheating for 10 seconds to 120 minutes at the temperature of 80 to 190 ℃ as required, and then raising the temperature to 200 to 500 ℃, preferably 250 to 400 ℃, so that the reaction is carried out for 10 to 300 minutes.

In the present invention, the solution containing the polybenzoxazole represented by the formula (2) obtained as described above may be used as a film-forming composition as it is, or the polybenzoxazole may be isolated once and then dissolved in the organic solvent again to be used as a film-forming composition.

By applying these film-forming compositions to a substrate and evaporating the solvent, a polybenzoxazole thin film can be formed. In this case, the temperature at which the solvent is evaporated can be about room temperature to 300 ℃, but is usually about 80 to 200 ℃.

In addition, a solution containing the polybenzoxazole precursor represented by the formula (1) can also be used as the film-forming composition.

After the film-forming composition is coated on a substrate, the film-forming composition is finally heated to 200 to 500 ℃ to evaporate the solvent and simultaneously close the precursor ring, thereby forming a thin film containing the polybenzoxazole represented by formula (2). In this case, as described above, it is preferable to use a method of preheating at 80 to 190 ℃ for 10 seconds to 120 minutes, then raising the temperature to 200 to 500 ℃, and reacting for about 10 minutes to about 300 minutes.

In each of the above-mentioned film-forming compositions, the solid content concentration of the polymer is not particularly limited, and is appropriately set according to the desired film thickness, application, and the like, and is preferably 0.1 to 80% by mass, more preferably 1 to 70% by mass, and further preferably 5 to 50% by mass.

The coating method of the composition is arbitrary, and for example, spin coating, dipping, flow coating, ink jet method, jet dispenser method, spray coating, bar coating, gravure coating, slit coating, roll coating, transfer printing, brush coating, blade coating, air knife coating, and the like can be used.

The substrate is not particularly limited, and examples thereof include substrates made of silicon, glass, polyimide, quartz, ceramics, and the like.

The heating method is not particularly limited, and for example, heating can be performed in an appropriate atmosphere such as air, an inert gas such as nitrogen, or vacuum using a hot plate or an oven.

The thickness of the thin film comprising polybenzoxazole is not particularly limited, and can be set appropriately according to the use of the thin film, and can be set to about 0.1 to 500 μm, and is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more, in view of sufficient water vapor barrier property.

The film-forming composition of the present invention may contain other additives such as a surfactant and a silane coupling agent in an amount of about 0.0001 to 5 parts by mass per 100 parts by mass of the polymer, as long as the effects of the present invention are not impaired.

The film comprising the polybenzoxazole of the present invention obtained as described above exhibits a thickness of less than 1g/m at 15 μm without using an inorganic component²Good water vapor barrier properties of day, while having heat resistance that can withstand TFT processing.

The film of the present invention having such characteristics can be suitably used as a substrate or an electrode substrate in the production of electronic devices such as liquid crystal displays, organic Electroluminescence (EL) displays, touch panels, organic EL elements, optical semiconductor (LED) elements, solid-state imaging elements, organic thin-film solar cells, dye-sensitized solar cells, and organic thin-film transistors (TFTs), and particularly can be suitably used as an electrode substrate of an organic EL element.

Examples

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples. The apparatus used is as follows.

(1)FT-IR

The device comprises the following steps: made by Thermo Fisher scientific Inc., NEXUS 670FTIR

(2) And (3) measuring the molecular weight: showa Denko K.K., Normal temperature Gel Permeation Chromatography (GPC) apparatus (GPC-101), and Shodex column (KD-803L)

(measurement conditions)

Column temperature: 40 deg.C

And (3) dissolving and separating liquid: dimethylformamide (DMF), 10mL/L

Flow rate: 1.0 mL/min

Calibration curve preparation standard samples: showa Denko K.K., SL-105, standard polystyrene (molecular weight about 580, 2970, 7200, 19900, 52400)

(3) And (3) measuring the film thickness: surfcorder ET-4000 Fine shape measuring apparatus manufactured by Xiaoban research Ltd

(4) Water vapor permeability: small-sized steam cup method (diameter 3cm)

A sample was prepared by placing 4.50g of calcium chloride in a steam cup and then holding the measurement membrane. The sample was allowed to stand in a constant temperature and humidity cell at 40 ℃ and 90% relative humidity for 48 hours, and the mass was measured. Further, the mass was measured after 48 hours, and the water vapor permeation amount was calculated from the mass increment.

In addition, the abbreviations of the compounds used in the examples are as follows.

PDA: p-phenylenediamine

DATP: 4, 4' -diamino-p-terphenyl

AHPE: 3,3 '-diamino-4, 4' -dihydroxydiphenyl ether

CBOCA: 2- (4-carboxyphenyl) benzoxazole-5-carboxylic acid

CBOCCl: 2- (4- (chlorocarbonyl) phenyl) benzoxazole-5-carbonyl chloride

And (3) PMDA: pyromellitic dianhydride

[1] Production of polyimide film for base substrate

Production example 1

PDA20.261g (0.1875mol) and DATP12.206g (0.0469mol) were dissolved in NMP617.4g, cooled to 15 ℃ and then added with PMDA50.112g (0.2298mol), and the mixture was reacted at 50 ℃ for 48 hours under a nitrogen atmosphere. The weight average molecular weight Mw of the obtained polymer was 82100, and the molecular weight distribution was 2.7. The polyamic acid was applied to a glass substrate with a bar coater. The substrate was baked at 80 ℃ for 30 minutes on a hot plate, and further baked at 450 ℃ for 1 hour after reducing the pressure in an oven, to obtain a polyimide-attached glass substrate having a film thickness of 11 μm.

[2] Production of polybenzoxazole precursor (composition for film formation)

EXAMPLE 1-1 preparation of precursor [3]

[ solution 10]

Reacting AHPE [2]]0.851g (3.66mmol) of the resulting solution was dissolved in NMP18g, and then CBOCCl [1] was added]1.149g (3.59mmol) was stirred at room temperature for 24 hours. Then, the obtained solution was poured into 500mL of pure water. The obtained precipitate was separated by filtration and dried at 80 ℃ under reduced pressure for 24 hours to obtain the objective precursor [3]](yield 95%). The resulting precursor [3]Has a weight average molecular weight Mw of 142000 and a molecular weight distribution of 8.8. Furthermore, 3300cm based on the phenolic hydroxyl group was confirmed by FTIR measurement^-1And 1651cm from the amido group^-1Peak of (2).

EXAMPLE 1-2 preparation of precursor [3]

[ solution 11]

Reacting AHPE [2]]0.911g (3.92mmol) of the residue was dissolved in NMP18g, to which was added CBOCCA [ 1']1.089g (3.84 mmol). Further, 0.793g (7.85 mmo) of triethylamine was addedl) and DBOP3.01g (7.85mmol) were stirred at room temperature for 24 hours. Then, the obtained solution was put into 500mL of a mixed solution of pure water and 2-propanol. The obtained precipitate was separated by filtration and dried at 80 ℃ under reduced pressure for 24 hours to obtain the objective precursor [3]](yield 99%). The resulting precursor [3]Has a weight average molecular weight Mw of 8000 and a molecular weight distribution of 5.6. Furthermore, 3300cm based on the phenolic hydroxyl group was confirmed by FTIR measurement^-1And 1651cm from the amido group^-1Peak of (2).

[3] Production of polybenzoxazole [4] (film)

[ example 2-1]

[ solution 12]

The precursor [3] obtained in example 1-1 was reacted]1g of the solution was dissolved in NMP9g and stirred at room temperature for 24 hours. The solution was coated on a glass substrate with a thickness of 250 μm using a bar coater. Then, the substrate was baked at 80 ℃ for 30 minutes on a hot plate, and further baked at 450 ℃ for 1 hour after reducing the pressure in an oven, to obtain a film having a thickness of 15 μm. The film was measured by FTIR, and found 3300cm^-1Peak sum of 1651cm^-1The peak of (A) disappeared and 1616cm from benzoxazole newly appeared^-1Peak of (2) (fig. 1). It was thus confirmed that polybenzoxazole [4] was obtained]。

Further, the solution was applied to the polyimide-equipped glass substrate produced in production example 1 by a bar coater, and then baked in the same manner, to obtain a polyimide film [4-1] having a polybenzoxazole [4] film thickness of 15 μm.

[ examples 2-2]

1g of the obtained precursor [3] was dissolved in NMP9g in the same manner as in example 2-1, and stirred at room temperature for 24 hours. The solution was coated on a polyimide-bearing glass substrate with a thickness of 500 μm using a bar coater. The substrate was then baked on a hot plate at 80 ℃ for 30 minutes. Further, the film was baked at 450 ℃ for 1 hour after reducing the pressure in an oven, whereby a polyimide film [4-2] having a polybenzoxazole [4] film thickness of 30 μm was obtained.

For [4-1] obtained in the above example 2-1]And [4-2] obtained in example 2-2]The film was measured for water vapor permeability, and as a result, it was found to be 0.74g/m in example 2-1²Day, 0.44g/m in example 2-2²Day, 1g/m²Day. Further, the polyimide film used as the substrate was 30g/m²Day. It was found that the polybenzoxazole of the present invention exhibits high water vapor barrier properties.

Claims

1. A polybenzoxazole precursor characterized by being represented by formula (1):

[ solution 1]

In the formula, R¹～R¹³Independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, or an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms, which may be substituted with a halogen atom, and n represents an integer of 2 or more.

2. A polybenzoxazole precursor according to claim 1, wherein R is¹～R¹³Is a hydrogen atom.

3. A polybenzoxazole characterized by being represented by formula (2):

[ solution 2]

In the formula, R¹～R¹³Independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, or an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms, which may be substituted with a halogen atom, and n represents 2 or moreThe above integer.

4. A polybenzoxazole according to claim 3, wherein R is¹～R¹³Is a hydrogen atom.

5. A film-forming composition comprising the polybenzoxazole precursor according to claim 1 or 2 and an organic solvent.

6. A film-forming composition comprising the polybenzoxazole according to claim 3 or 4 and an organic solvent.

7. A film comprising a polybenzoxazole according to claim 3 or 4.

8. A method for producing a thin film, comprising applying the film-forming composition according to claim 5 to a substrate, and heating the composition to evaporate the organic solvent and to close the ring of the polybenzoxazole precursor.

9. A method for producing a thin film, comprising applying the film-forming composition according to claim 6 to a substrate and evaporating the organic solvent.

10. An electronic device having the thin film according to claim 7 as a substrate.

11. The electronic device according to claim 10, which is an organic electroluminescent element.

12. The method for producing a polybenzoxazole precursor according to claim 1, wherein a dicarboxylic acid compound represented by formula (3) is reacted with a diamine compound represented by formula (4),

[ solution 3]

In the formula, R¹～R⁷Represents the same meaning as above, X represents a halogen atom, a hydroxyl group, a phenoxy group, a2, 4, 5-trichlorophenoxy group, a 1H- [1,2, 3]]Triazolyloxy [4,5-b ]]Pyridyl, 1H-benzo [ d ]][1,2,3]A triazolyloxy group, a2, 3-dihydro-2-thioxo-3-benzoxazolyl group or a 4, 6-dimethoxy-1, 3, 5-triazinyloxy group,

[ solution 4]

In the formula, R⁸～R¹³The same meanings as described above are indicated.

13. The method for producing a polybenzoxazole according to claim 3, wherein a polybenzoxazole precursor represented by formula (1) is heated to be closed in a ring:

[ solution 5]

In the formula, R¹～R¹³The same meanings as described above are indicated.