阅读说明：本技术 向玻璃基板的涂覆用溶液 (Solution for coating glass substrate ) 是由 杉本洋辅 山田祐己 吉田猛 繁田朗 越后良彰 于 2018-12-04 设计创作，主要内容包括：本发明提供一种涂覆用溶液,其在将聚酰胺酸(PAA)涂膜进行热固化时,即使加快升温速度也能够充分确保向玻璃基板的密合性,且在热固化后能够容易以聚酰亚胺膜的形式从玻璃基板剥离,保存稳定性良好。本发明涉及一种向玻璃基板的涂覆用溶液,由PAA、酰胺系溶剂和烷氧基硅烷化合物构成,其特征如下：1)烷氧基硅烷化合物的含量相对于PAA质量为超过5ppm且小于100ppm,2)烷氧基硅烷化合物的分子量为100～300。(The invention provides a coating solution which can fully ensure the adhesion to a glass substrate even if the temperature rising speed is increased when a polyamide acid (PAA) coating film is subjected to heat curing, can be easily peeled off from the glass substrate in the form of a polyimide film after the heat curing, and has good storage stability. The invention relates to a solution for coating a glass substrate, which comprises PAA, an amide solvent and an alkoxy silane compound, and is characterized in that: 1) the content of the alkoxysilane compound is more than 5ppm and less than 100ppm with respect to the mass of PAA, and 2) the molecular weight of the alkoxysilane compound is 100 to 300.)

1. A solution for coating a glass substrate, comprising a polyamic acid (PAA), an amide solvent, and an alkoxysilane compound, characterized by comprising:

1) the content of the alkoxysilane compound is more than 5ppm and less than 100ppm with respect to the mass of PAA,

2) the molecular weight of the alkoxysilane compound is 100 to 300.

2. A method for producing a solution for coating a glass substrate, which comprises a polyamic acid (PAA) as a Polyimide (PI) precursor, an amide solvent, and an alkoxysilane compound, characterized in that when the alkoxysilane compound having a molecular weight of 100 to 300 is added to the PAA solution, the amount of the alkoxysilane compound added is adjusted to be more than 5ppm and less than 100ppm with respect to the mass of the PAA, and the amount of the alkoxysilane compound added is adjusted in accordance with the thickness of a target PI film.

3. A method for producing a laminate comprising a PI film and a glass substrate, wherein the coating solution according to claim 1 is applied to a glass substrate, dried, and then thermally cured to form a Polyimide (PI) film on the glass substrate, wherein the Polyimide (PI) film is thermally cured by continuously raising the temperature, and the upper limit temperature during thermal curing is set to 350 to 500 ℃.

Technical Field

The present invention relates to a coating solution containing polyamic acid (PAA) as a Polyimide (PI) precursor, which is applied to a glass substrate.

Background

Conventionally, in the field of Flat Panel Displays (FPDs) such as liquid crystal displays (L CD), Plasma Display Panels (PDP), and organic E L displays (O L ED), and electronic devices such as electronic paper, mechanisms in which electronic elements are formed on a glass substrate have been mainly used, but glass substrates are rigid and lack flexibility, and therefore have a problem that flexibility is not easily obtained.

Therefore, a method of using a PI film having flexibility and good heat resistance and dimensional stability as a flexible substrate has been proposed. For example, it is proposed to use a laminate of: a PAA solution that is a precursor of PI is applied and dried to form a PAA coating film, which is thermally cured to form a laminate in which a PI film is laminated and integrated on a glass substrate. That is, after an electronic component is formed on the surface of the PI film laminated on the glass substrate, the PI film is finally peeled off from the glass substrate, thereby producing a flexible substrate. In the heat curing process, when the PAA coating film formed on the glass substrate is converted into a PI film, the coating film may be peeled off from the glass substrate or air bubbles may remain on the surface of the PI film. This problem becomes remarkable particularly when the temperature rising rate at the time of thermosetting is increased in order to improve the production efficiency.

Therefore, it is necessary to sufficiently ensure adhesion of the PAA coating film to the glass substrate during heat curing. As a method for securing this adhesion, a method is known in which a solution prepared by blending an alkoxysilane compound with PAA is applied to a glass substrate, and then the PAA coating film is thermally cured to form a PI film. For example, patent document 1 (example) discloses an example of a PAA solution in which 200 to 500ppm of an alkoxysilane compound and 500 to 800ppm of a silicone surfactant are mixed in mass with respect to PAA. Patent document 2 (claim 1) discloses a method for improving the adhesion between a PI film and a glass substrate by using a PAA solution in which 100 to 20000ppm of an alkoxysilane compound is added to the mass of PAA. Patent document 3 (claim 1) discloses a method for improving the adhesion between a PI film and a glass substrate by using an alkoxysilane-modified PAA solution obtained by heating a PAA solution containing 500 to 1000ppm of an alkoxysilane compound based on the mass of PAA to about 50 ℃.

Disclosure of Invention

However, in the methods disclosed in the related art, since a large amount of an alkoxysilane compound is mixed in a PAA solution, there is a concern that the mechanical properties, electrical properties, optical properties, and the like of the obtained PI film are impaired. Further, the adhesion between the PI film and the glass substrate is too strong, and there is a possibility that the PI film is not easily peeled off when the PI film is finally peeled off from the glass substrate after the electronic element is formed on the surface of the PI film. Further, these PAA solutions may change in viscosity during storage, and it is difficult to ensure good storage stability.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to provide a coating solution which can sufficiently ensure the adhesion of a PAA coating film, can be easily peeled off from a glass substrate as a PI film after heat curing, and has good storage stability.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a PAA solution containing a specific amount of a specific alkoxysilane compound, and have completed the present invention.

The gist of the present invention is as follows.

< 1 > A solution for coating a glass substrate, comprising PAA, an amide solvent and an alkoxysilane compound, characterized by comprising:

1) the content of the alkoxysilane compound is more than 5ppm and less than 100ppm with respect to the mass of PAA,

2) the molecular weight of the alkoxysilane compound is 100 to 300.

< 2 > A method for producing a solution for coating a glass substrate, comprising a polyamic acid (PAA) which is a precursor of a Polyimide (PI), an amide solvent, and an alkoxysilane compound, characterized in that when the alkoxysilane compound having a molecular weight of 100 to 300 is added to the PAA solution, the amount of the alkoxysilane compound added is more than 5ppm and less than 100ppm with respect to the mass of the PAA, and the amount of the alkoxysilane compound added is adjusted according to the thickness of the target PI film.

< 3 > A method for producing a laminate comprising a PI film and a glass substrate, wherein a Polyimide (PI) film is formed on the glass substrate by applying the coating solution < 1 > to the glass substrate, drying the coating solution, and then thermally curing the coating solution, wherein the Polyimide (PI) film is thermally cured by continuously raising the temperature, and the upper limit temperature of the Polyimide (PI) film during thermal curing is set to 350 to 500 ℃.

By using the PAA solution of the present invention, adhesion to a glass substrate can be sufficiently ensured when a PAA coating film is thermally cured. In addition, the PI film after heat curing can be easily peeled off from the glass substrate in the form of a PI film. Therefore, the PAA solution can be suitably used as a solution for manufacturing a flexible substrate including a PI film on which an electronic element is formed.

Detailed Description

The present invention will be described in detail below.

The PAA solution of the present invention is coated on a glass substrate. As the glass substrate, for example, a substrate made of soda lime glass, borosilicate glass, alkali-free glass, or the like can be used, and among these, an alkali-free glass substrate can be preferably used. These glass substrates may be subjected to a known surface treatment such as a silane coupling agent treatment.

The thickness of the glass substrate is preferably 0.3 to 5.0 mm. If the thickness is thinner than 0.3mm, the workability of the substrate may be deteriorated. In addition, if the thickness is thicker than 5.0mm, the productivity may be lowered.

The PAA solution of the present invention is obtained by adding an alkoxysilane compound to a PAA solution obtained by polymerizing tetracarboxylic acids and diamines, which are raw materials, in an amide solvent in approximately equimolar amounts. Here, "substantially equimolar" means that the diamine is 0.9 to 1.0 mol based on 1 mol of the tetracarboxylic acid.

Examples of the tetracarboxylic acids (tetracarboxylic acids, dianhydrides thereof, esters thereof, and the like) include pyromellitic acid, 3,3 ', 4, 4' -biphenyltetracarboxylic acid, 4,4 '-hexafluoroisopropylidene phthalic acid, 2,3, 3', 4 '-biphenyltetracarboxylic acid, 2', 3,3 '-biphenyltetracarboxylic acid, 4, 4' -oxydiphthalic acid, 3,3 ', 4, 4' -benzophenone tetracarboxylic acid, 3,3 ', 4, 4' -diphenylsulfone tetracarboxylic acid, p-terphenyltetracarboxylic acid, and m-terphenyltetracarboxylic acid. These tetracarboxylic acids can be used individually or in the form of mixtures. Among these, from the viewpoint of the heat resistance and dimensional stability of the obtained PI, 3 ', 4,4 ' -biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), 4,4 ' -hexafluoroisopropylidene phthalic dianhydride (6FDA), and a mixture thereof are preferable.

Examples of the diamine include p-Phenylenediamine (PDA), m-phenylenediamine, 4 ' -Oxyaniline (ODA), 3 ' -bis (trifluoromethyl) -4,4 ' -diaminobiphenyl (TFMB), 3,4 ' -diaminodiphenyl ether, 4 ' -diaminodiphenylmethane, 3 ' -dimethyl-4, 4 ' -diaminodiphenylmethane, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 1, 2-bis (anilino) ethane, diaminodiphenylsulfone, diaminobenzanilide, diaminobenzoate, diaminodiphenylsulfide, 2-bis (p-aminophenyl) propane, 2-bis (p-aminophenyl) hexafluoropropane, 1, 5-diaminonaphthalene, diaminotoluene, and the like, Diaminobenzotrifluoride, 1, 4-bis (p-aminophenoxy) benzene, 4 '-bis (p-aminophenoxy) biphenyl, diaminoanthraquinone, 4' -bis (3-aminophenoxyphenyl) diphenylsulfone, and the like. These aromatic diamines may be used alone or in a mixture. Among these, PDA, ODA, TFMB and mixtures thereof are preferable from the viewpoint of the heat resistance and dimensional stability of the obtained PI.

Examples of the amide solvent include N-methyl-2-pyrrolidone (NMP), N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), and the like. These solvents may be used alone or in the form of a mixture. Among these, NMP, DMAc, and a mixture thereof are preferable from the viewpoint of solubility in PAA. These solvents are preferably dehydrated, and the water content thereof is preferably 500ppm or less, more preferably 200ppm or less. By setting as described above, the water content in the PAA solution can be reduced, and hydrolysis of the alkoxysilane compound and the like during storage can be prevented.

The reaction temperature for producing the PAA solution is preferably-30 to 70 ℃, and more preferably-15 to 60 ℃. In this reaction, the order of addition of the monomer and the solvent is not particularly limited, and may be any order. The solid content concentration of PAA is preferably 1 to 50% by mass, and more preferably 5 to 30% by mass. The PAA may be partially imidized. The viscosity of the PAA solution thus obtained is preferably 3Pa · s to 100Pa · s as the solution viscosity at 30 ℃. Commercially available products may be used as the PAA solution. As commercially available products, it is preferable to use "U ImideVarnish AH, AR" (manufactured by Youngco), "UPIA-ST" (manufactured by Yokoku corporation), and "PI-2611" (manufactured by Hitachi chemical Dupont MicroSystems). These are all solutions of PAA in NMP obtained using BPDA as the acid component and PDA as the diamine component.

The PAA solution of the present invention can be obtained by compounding an alkoxysilane compound in the PAA solution obtained in the above-described manner. Here, the amount of the alkoxysilane compound to be added needs to be more than 5ppm and less than 100ppm with respect to the mass of PAA. Further, the molecular weight of the alkoxysilane compound is required to be 100 to 300.

Examples of such alkoxysilane compounds include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-Aminopropyltrimethoxysilane (APMS), 3-Aminopropyltriethoxysilane (APES), 3-triethoxysilyl-N- (1, 3-dimethyl-butylene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, p-vinyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, N-tert-butyl-3-aminopropyltrimethoxysilane, N-tert-butyl-3-aminobutylidenedimethoxysilane, N-tert-butylidenedimethoxysilane, N-propyltrimethoxysilane, N-ethyltrimethoxysilane, p, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-Ureidopropyltriethoxysilane (UPES), 3-ureidopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, etc. Among these, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-ureidopropyltriethoxysilane and mixtures thereof are preferred.

By defining the amount and molecular weight of the alkoxysilane compound as described above, when the PAA coating film is thermally cured, adhesion to the glass substrate can be sufficiently ensured even if the temperature rise rate is increased, and the PAA coating film can be easily peeled off from the glass substrate as a PI film after thermal curing.

The PAA solution of the present invention may also be modified with an alkoxysilane compound in part by heating it to about 50 ℃.

In the PAA solution of the present invention, by setting the amount of the alkoxysilane compound to the above range, adhesion to a glass substrate and peelability can be ensured even if the temperature rise rate is increased, and therefore, it is preferable to substantially not mix other additives which may impair the mechanical properties of the PI film, for example, a surfactant such as a silicone surfactant and a fluorine-based surfactant as disclosed in patent document 1. Here, "not substantially blended" means that the blending amount is less than 1 ppm. By setting in this manner, the original good mechanical properties, electrical properties, optical properties, and the like of the PI can be ensured.

The PAA solution of the present invention may contain fine particles of silica, alumina, or the like in a range that does not impair optical characteristics such as transparency of the PI film. The volume average particle diameter of these fine particles (based on dynamic light scattering) is preferably 10nm to 100 nm. The amount of the PAA is preferably 5 to 20% by mass based on the mass of PAA.

Other polymers may be added to the PAA solution of the present invention within a range not to impair the effects of the present invention.

The PAA solution of the present invention is applied to a glass substrate, dried, and thermally cured to convert a PAA coating film into a PI film to prepare a laminate, and then an electronic element is formed on the surface, and finally the PI film is peeled off from the glass substrate, thereby preparing a flexible substrate.

When the PAA solution of the present invention is applied to a glass substrate, the amount of alkoxysilane compound to be added is preferably adjusted according to the thickness of the target PI film. That is, the amount of the PI film to be blended is preferably reduced as the thickness of the PI film is reduced. Further, it is preferable that the amount of the PI film is increased as the thickness of the PI film is increased. By setting in this manner, adhesion to the glass substrate and peelability from the glass substrate can be more sufficiently ensured, and the amount of the alkoxysilane compound to be added can be minimized depending on the thickness.

As a method for applying the PAA solution to the glass substrate, coating can be performed continuously or batchwise by using a known method such as mesa coating, dip coating, bar coating, spin coating, die coating, spray coating, and the like.

For drying and thermosetting, a general hot air dryer, an infrared lamp, or the like can be used. The drying temperature is preferably 40 to 150 ℃ and the drying time is preferably about 5 to 30 minutes.

In the thermosetting of the dried PAA coating film obtained in the above manner, it is preferable to continuously raise the temperature to prepare a thermosetting PI film. Here, "continuously raising the temperature" means raising the temperature of the atmosphere at the time of thermal curing at a controlled temperature raising rate. From the viewpoint of ensuring the adhesion of the PAA coating film to the glass substrate, the temperature increase rate is preferably 1 to 15 ℃/min, more preferably 3 to 10 ℃/min. The upper limit temperature at the time of temperature rise is preferably 350 to 500 ℃. The temperature raising process may include a step of maintaining the atmospheric temperature for a certain period of time during the temperature raising.

In the examples of patent document 1, there is described a method in which, as a heat curing condition, after coating so that the film thickness after curing becomes 20 μm, heat curing is performed under the condition of "A: 140 ℃ × 1hr +250 ℃ × 1hr +350 ℃ × 1hr, B: 140 ℃ × 1hr +450 ℃ × 1hr, C: 140 ℃ × 1hr +500 ℃ × 1 hr", and a method in which heat curing is performed by discontinuous temperature rise under the condition of "baking (drying) with a hot plate at 130 ℃ for 2 minutes to have a thickness of 18 μm" as a heat curing condition "in the examples of patent document 2, film formation is performed, next, heat curing is performed at 200 ℃ for 30 minutes using a curing furnace, further heat curing is performed at 450 ℃ for 60 minutes to perform heat curing, polyimide in a resin composition is subjected to imidization for 2 minutes" and a sufficient heat curing is not obtained by a polyimide precursor in a polyimide imide solution, and a polyimide imide precursor is used in a polyimide imide film formation method in which the polyimide imide solution, and a polyimide imide is used in a polyimide imide film formation method in which a discontinuous temperature rise under a discontinuous temperature reduction condition.

Since the PAA coating film obtained from the PAA solution of the present invention has good adhesion to a glass substrate, the PAA coating film can be prevented from generating bubbles or swelling even if the temperature rise rate at the time of temperature rise is set to a fast temperature rise rate of, for example, 3 to 10 ℃/min as described above.

The laminate obtained as described above is useful for manufacturing electronic devices because it is possible to easily peel off the PI film from the glass substrate after forming an electronic element on the surface of the PI film.

The thickness of the PI film after peeling from the glass substrate is preferably 1 to 50 μm, more preferably 5 to 40 μm. When the PAA solution of the present invention is used, the amount of alkoxysilane to be added is adjusted, whereby the PAA solution can be thermally cured without causing bubbles or swelling even when the thickness is as thick as about 30 μm. For example, when the thickness of the target PI film is 10 μm or more (particularly, 15 μm to 40 μm), the amount of the alkoxysilane compound to be incorporated is preferably 25ppm or more (particularly, 25ppm or more and less than 100 ppm).

As the electronic component, all electronic components conventionally used in the field of electronic devices can be used. As a method for forming an electronic element, a method known in the field of electronic devices using a PI film as a flexible substrate can be used.

Examples of the electronic devices include Flat Panel Displays (FPD) such as a liquid crystal display (L CD), a Plasma Display Panel (PDP), and an organic E L display (O L ED), and flexible devices such as electronic paper.