WO2019111870A1 - Solution to be coated onto glass substrate - Google Patents

Abstract

The present invention provides a coating solution having good storage stability, which can be adhered satisfactorily onto a glass substrate even when the temperature rising rate is increased in the thermal curing of a polyamic acid (PAA) coating film, and which can be thermally cured into a polyimide film that can be detached from the glass substrate easily. The present invention relates to a solution to be coated onto a glass substrate, which contains a PAA, an amide-type solvent and an alkoxysilane compound and is characterized as follows: (1) the content of the alkoxysilane compound is 5 to 100 ppm exclusive relative to the mass of the PAA; and (2) the molecular weight of the alkoxysilane compound is 100 to 300 inclusive.

Description

Coating solution for glass substrate

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

Conventionally, in the field of electronic devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), flat panel displays (FPDs) such as organic EL displays (OLEDs), and electronic paper, electronic elements are mainly formed on a glass substrate However, since the glass substrate is rigid and lacks in flexibility, it is difficult to be flexible.

Therefore, a method has been proposed in which a PI film having flexibility and good heat resistance and dimensional stability is used as a flexible substrate. For example, a solution of PAA, which is a precursor of PI, is coated and dried to form a film of PAA, and the film is thermally cured to use a PI film laminated and integrated on a glass substrate. Proposed. That is, after an electronic element is formed on the surface of a PI film laminated on a glass substrate, the PI film is finally peeled from the glass substrate to form a flexible substrate. In the process of the heat curing, when a PAA coating film formed on a glass substrate is converted to a PI film, the coating film peels off from the glass substrate or air bubbles remain on the surface of the PI film to be formed Sometimes. In particular, this problem becomes noticeable when the temperature rising rate during heat curing is increased in order to increase production efficiency.

Therefore, at the time of heat curing, it is necessary to ensure sufficient adhesion of the PAA coating film to the glass substrate. As a method for securing the adhesion, a method is known in which a solution obtained by blending an alkoxysilane compound in PAA is applied on 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 500 ppm of an alkoxysilane compound and 500 to 800 ppm of a silicone surfactant are blended with respect to the mass of PAA. Patent Document 2 (Claim 1) discloses a method of improving the adhesion between a PI film and a glass substrate by using a PAA solution containing 100 to 20000 ppm of an alkoxysilane compound based on the mass of PAA. There is. In Patent Document 3 (claim 1), PI is obtained by using an alkoxysilane-modified PAA solution obtained by heating a PAA solution containing 500 to 1000 ppm of an alkoxysilane compound to the mass of PAA to about 50 ° C. A method of improving the adhesion between a film and a glass substrate is disclosed.

Patent No. 6067740 Patent No. 6172139 gazette International Publication 2016/024457

However, in the method disclosed in the prior art, since a large amount of the alkoxysilane compound is blended in the PAA solution, there is a possibility that the mechanical properties, electrical properties, optical properties and the like of the obtained PI film may be impaired. In addition, the adhesion between the PI film and the glass substrate becomes too strong, and there is a possibility that it becomes difficult to peel off when the PI film is finally peeled from the glass substrate after forming the electronic element on the surface of the PI film. Furthermore, the viscosity of these PAA solutions may change during storage, and there is also a problem that it is difficult to ensure good storage stability.

Therefore, the present invention solves the above-mentioned problems, and after sufficiently securing the adhesion of the PAA coating film, it can be easily peeled off from the glass substrate as a PI film after heat curing, storage stable The purpose is to provide a coating solution with good properties.

As a result of earnestly researching in order to solve the said subject, it discovered that the said subject was solved by using the PAA solution which contains a specific alkoxysilane compound in a specific amount, and came to completion of this invention.

The present invention is as follows.
It is a solution for coating to the glass substrate which consists of <1> PAA, an amide system solvent, and an alkoxysilane compound, Comprising: The solution for coating to the glass substrate characterized by the following.
1) The alkoxysilane compound content is more than 5 ppm and less than 100 ppm based on the mass of PAA.
2) The molecular weight of the alkoxysilane compound is 100 or more and 300 or less.
<2> A method for producing a coating solution for a glass substrate comprising a polyamic acid (PAA), which is a polyimide (PI) precursor, an amide solvent and an alkoxysilane compound, wherein the PAA solution has a molecular weight of When blending an alkoxysilane compound having 100 or more and 300 or less, the blending amount of the alkoxysilane compound is made more than 5 ppm and less than 100 ppm with respect to the mass of PAA, and the blending amount of the alkoxysilane compound is PI A method for producing a coating solution for a glass substrate, which is adjusted according to the thickness of a film.
<3> In the method of forming a polyimide (PI) film on a glass substrate by coating and drying the coating solution described in <1> onto a glass substrate, the thermosetting is continuously performed. A method for producing a laminate comprising a PI film and a glass substrate, characterized by carrying out by raising the temperature and setting the upper limit temperature during heat curing to 350 ° C. or more and 500 ° C. or less.

By using the PAA solution of the present invention, adhesion to a glass substrate can be sufficiently ensured when the PAA coating film is thermally cured. Moreover, PI film after thermosetting can be easily peeled as a PI film from a glass substrate. Accordingly, this PAA solution can be suitably used as a solution for producing a flexible substrate consisting of a PI film on which an electronic device is formed.

Hereinafter, the present invention will be described in detail.

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, alkali-free glass substrates can be preferably used. These glass substrates may be subjected to known surface treatment such as silane coupling agent treatment.

The thickness of the glass substrate is preferably 0.3 to 5.0 mm. If the thickness is less than 0.3 mm, the handleability of the substrate may be reduced. In addition, if the thickness is greater than 5.0 mm, productivity may be reduced.

The PAA solution of the present invention can be obtained by blending an alkoxysilane compound into a PAA solution obtained by polymerizing an equimolar amount of tetracarboxylic acids and diamines as raw materials in an amide solvent. Here, “approximately equimolar” means that the diamine is 0.9 mol or more and 1.0 mol or less with respect to 1 mol of the tetracarboxylic acid.

Examples of tetracarboxylic acids (tetracarboxylic acids, dianhydrides or esters thereof) include, for example, pyromellitic acids, 3,3 ′, 4,4′-biphenyltetracarboxylic acids, 4,4′-hexafluoroisopropylidene Phthalic acids, 2,3,3 ', 4'-biphenyltetracarboxylic acids, 2,2', 3,3'-biphenyltetracarboxylic acids, 4,4'-oxydiphthalic acids, 3,3 ', 4,4' -Benzophenone tetracarboxylic acids, 3,3 ', 4,4'-diphenyl sulfone tetracarboxylic acids, p-terphenyl tetracarboxylic acids, m-terphenyl tetracarboxylic acids and the like can be mentioned. These tetracarboxylic acids can be used alone or as a mixture. Among these, 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), pyromellitic acid dianhydride (PMDA), 4,4'-hexafluoroisopropylidene phthalic acid dianhydride (6FDA) and mixtures thereof are preferred from the viewpoint of the heat resistance and dimensional stability of the obtained PI.

Examples of the diamine include p-phenylenediamine (PDA), m-phenylenediamine, 4,4'-oxydianiline (ODA), 3,3'-bistrifluoromethyl-4,4'-diaminobiphenyl (TFMB) 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,2-bis (anilino) ethane, diaminodiphenyl sulfone, diaminobenzanilide, diaminobenzoate, diaminodiphenyl sulfide, 2,2-bis (p-aminophenyl) propane, 2,2-bis (p-aminophenyl) hexa Fluoropropane, 1,5-diaminonaphthalene, diamino Ruene, diaminobenzotrifluoride, 1,4-bis (p-aminophenoxy) benzene, 4,4'-bis (p-aminophenoxy) biphenyl, diaminoanthraquinone, 4,4'-bis (3-aminophenoxyphenyl) Diphenyl sulfone etc. can be mentioned. These aromatic diamines can be used alone or as a mixture. Among these, PDA, ODA, TFMB and mixtures thereof are preferred in view of the heat resistance and dimensional stability of the obtained PI.

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

The reaction temperature for producing the PAA solution is preferably −30 to 70 ° C., and more preferably −15 to 60 ° C. 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 3 Pa · s or more and 100 Pa · s or less as the solution viscosity at 30 ° C. from the viewpoint of coatability. In addition, commercial products can also be used for these PAA solutions. As a commercial product, it is preferable to use "U imide varnish AH, AR" (manufactured by Unitika), "UPIA-ST" (manufactured by Ube Industries, Ltd.), "PI-2611" (manufactured by Hitachi Chemical DuPont MicroSystems), etc. . These are all NMP solutions of PAA obtained using BPDA as an acid component and PDA as a diamine component.

The PAA solution of the present invention can be obtained by blending an alkoxysilane compound with the PAA solution obtained as described above. Here, it is necessary to make the compounding quantity of an alkoxysilane compound more than 5 ppm and less than 100 ppm with respect to PAA mass. Furthermore, the molecular weight of the alkosilane compound needs to be 100 or more and 300 or less.

As such alkoxysilane compounds, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane (APMS), 3-aminopropyltriethoxysilane (APES), 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, vinyltrimethoxy Silane, vinyltriethoxysilane, p-styryltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3 -Glycydoxypi Methyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane Silane, 3-acryloxypropyltrimethoxysilane, 3-ureidopropyltriethoxysilane (UPES), 3-ureidopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyl Triethoxysilane etc. are mentioned. Among these, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-ureidopropyltriethoxysilane, and mixtures thereof are preferred.

By defining the compounding amount and the molecular weight of the alkoxysilane compound as described above, adhesion to the glass substrate can be sufficiently ensured even when the temperature rising rate is increased when the PAA coating film is thermally cured. And, after thermosetting, it can be easily peeled off from the glass substrate as a PI film. In addition, by using such a composition, it is possible to obtain a PAA solution with good storage stability. The compounding amount of the alkoxysilane compound can be confirmed by liquid chromatography-mass spectrometry (LC-MS).

The PAA solution of the present invention can also be partially denatured with an alkoxysilane compound by heating the solution to about 50 ° C.

In the PAA solution of the present invention, by defining the compounding amount of the alkoxysilane compound in the above range, the adhesion to the glass substrate and the releasability can be secured even if the temperature raising rate is increased, so the PI film Additives such as silicone surfactants as disclosed in Patent Document 1 and surfactants such as fluorosurfactants are substantially incorporated. Preferably not. Here, "not substantially blended" means that the blending amount is less than 1 ppm. By doing so, it is possible to secure good mechanical properties, electrical properties, optical properties and the like inherent to PI.

In the PAA solution of the present invention, fine particles of silica, alumina or the like may be blended as long as the optical properties such as the transparency of the PI film are not impaired. The volume average particle diameter (by dynamic light scattering) of these fine particles is preferably 10 nm or more and 100 nm or less. Moreover, it is preferable that the compounding quantity sets it as 5 mass% or more and 20 mass% or less with respect to PAA mass.

Other polymers may be added to the PAA solution of the present invention as long as the effects of the present invention are not impaired.

The PAA solution of the present invention is applied to a glass substrate, dried, and thermally cured to convert the PAA coating film into a PI film to form a laminate, after which an electronic element is formed on this surface, and finally the PI film By peeling from the glass substrate, a flexible substrate can be obtained.

When the PAA solution of the present invention is applied to a glass substrate, it is preferable to adjust the compounding amount of the alkoxysilane compound according to the thickness of the target PI film. That is, as the thickness of the PI film is thinner, it is preferable to lower the blending amount. Moreover, it is preferable to make compounding quantity high, so that the thickness of PI film is thick. In this manner, the adhesion to the glass substrate and the removability from the glass substrate can be sufficiently secured, and the blending amount of the alkoxysilane compound can be minimized according to the thickness.

The PAA solution can be applied to a glass substrate continuously or batchwise using a known method such as a table coater, dip coater, bar coater, spin coater, die coater, spray coater or the like.

In the drying and heat curing, a conventional hot air dryer, an infrared lamp, etc. can be used. The drying temperature is preferably 40 ° C. to 150 ° C., and the drying time is preferably about 5 to 30 minutes.

In the case of heat curing of the PAA coating film after drying obtained as described above, it is preferable to raise the temperature continuously to obtain a heat cured PI film. Here, "continuously raising the temperature" refers to raising the temperature of the atmosphere at the time of thermal curing at a controlled rate of temperature increase. The heating rate is preferably 1 ° C./min to 15 ° C./min, and preferably 3 ° C./min to 10 ° C./min, from the viewpoint of securing the adhesion of the PAA coating film to the glass substrate. More preferable. It is preferable that the upper limit temperature at the time of temperature rising shall be 350 degreeC or more and 500 degrees C or less. The temperature raising process may include a step of holding the ambient temperature for a certain period during the temperature raising.
The atmosphere at the time of heat curing is preferably an inert gas atmosphere such as nitrogen or argon. In the above-mentioned Patent Documents 1 to 3, there is no description or suggestion about a method of thermally raising the PAA coating film by continuously raising the temperature. That is, in the example of Patent Document 1, as a thermosetting condition, after application so that the film thickness after curing becomes 20 μm, “A: 140 ° C. × 1 hr + 250 ° C. × 1 hr + 350 ° C. × 1 hr, B: 140 ° C. × 1 hr + 450 A method of heat curing under conditions such as ° C × 1 hr, C: 140 ° C. × 1 hr + 500 ° C. × 1 hr is described, which is a method by discontinuous temperature elevation. Further, in the example of Patent Document 2, as heat curing conditions, “baked (dried) for 2 minutes with a hot plate at 130 ° C. to form a film having a thickness of 18 μm. Then, using a curing furnace, 200 ° C. C. for 30 minutes and heat curing at 450.degree. C. for 60 minutes to imidize the polyimide precursor in the resin composition is described, which is a method by discontinuous temperature elevation. When such a discontinuous temperature rising method is used, when the compounding quantity of the alkoxysilane compound in PAA solution is reduced, sufficient adhesiveness of the obtained PI film may not be ensured.

Since the PAA coating film obtained from the PAA solution of the present invention has good adhesion to the glass substrate, the temperature raising rate at the time of temperature rising is as fast as, for example, 3 ° C / min to 10 ° C / min as described above. Even at the temperature rising rate, it is possible to prevent the generation of air bubbles and blisters in the PAA coating film.

The laminate obtained as described above is useful for manufacturing an electronic device because the PI film can be easily peeled off from the glass substrate after forming the electronic device on the surface of the PI film.

The thickness of the PI film after peeling from the glass substrate is preferably 1 μm or more and 50 μm or less, and more preferably 5 μm or more and 40 μm or less. In the case of using the PAA solution of the present invention, by adjusting the blending amount of the alkoxysilane, even if the thickness is relatively thick, for example, about 30 μm, heat curing can be performed without generating air bubbles or blisters. It can be carried out. For example, when the thickness of the target PI film is 10 μm or more (particularly, 15 μm or more and 40 μm or less), the blending amount of the alkoxysilane compound is preferably 25 ppm or more (particularly, 25 ppm or more and less than 100 ppm).

As the electronic device, any electronic device conventionally used in the field of electronic devices can be used. As a method of forming the electronic device, a method known in the field of electronic devices using PI film as a flexible substrate can be adopted.

Examples of the electronic device include a flexible device such as a flat panel display (FPD) such as a liquid crystal display (LCD), a plasma display panel (PDP), an organic EL display (OLED) and the like, and an electronic paper.

<PAA solution A-1>
As the PAA solution A-1, U imide varnish AR (BPDA / PDA solution in NMP) was prepared. The solution viscosity of this PAA solution at 30 ° C. was 4.3 Pa · s, and the PAA solid content concentration was 19.1% by mass with respect to A-1 mass.

<PAA solution B-1>
In a glass reaction vessel, PDA (0.600 mol) and NMP (polymerization solvent) having a water content of 200 ppm or less were charged under nitrogen atmosphere and stirred to dissolve PDA. BPDA (0.612 mol) is gradually added while cooling this solution to 30 ° C. or less with a jacket, and then the polymerization reaction is carried out at 60 ° C. for 100 minutes, and the solution viscosity at 25 ° C. is 75 Pa · s, A PAA solution having a solid content concentration of PAA of 20% by mass relative to the mass of B-1 was obtained.

<PAA solution C-1>
In a glass reaction vessel, under a nitrogen atmosphere, PDA (0.550 mol) and ODA (0.050 mol) are charged with NMP (polymerization solvent) having a water content of 200 ppm or less, and stirred. Dissolved. BPDA (0.605 mol) is gradually added while cooling this solution to 30 ° C. or less with a jacket, and then the polymerization reaction is carried out at 60 ° C. for 100 minutes, and the solution viscosity at 25 ° C. is 98.5 Pa · s. Thus, a PAA solution having a PAA solid concentration of 20% by mass relative to C-1 mass was obtained.

<PAA solution D-1>
In a glass reaction vessel, under nitrogen atmosphere, PDA (0.5 mol) and TFMB (0.1 mol) are charged with NMP (polymerization solvent) having a water content of 200 ppm or less and stirred, and PDA and TFMB Dissolved. This solution was gradually added to BPDA (0.505 mol) and 6FDA (0.1 mol) while cooling this solution to 30 ° C. or less with a jacket, and then allowed to polymerize at 60 ° C. for 100 minutes to obtain a solution at 25 ° C. A PAA solution with a solution viscosity of 86.4 Pa · s and a PAA solid content concentration of 20% by mass based on D-1 mass was obtained.

Example 1
30 ppm of 3-aminopropyltrimethoxysilane (APMS molecular weight: 179.3) was added to A-1 at room temperature (25 ° C.) with respect to the mass of PAA and stirred to obtain a uniform PAA solution (A I got -2).
A-2 is coated by a table coater on the surface of an alkali-free glass substrate (20 cm square) having a thickness of 0.7 mm, dried at 45 ° C. for 10 minutes, at 70 ° C. for 5 minutes, and at 150 ° C. for 5 minutes. A film was formed.
Next, the PAA coating film was thermally cured by raising the temperature to 450 ° C. at a heating rate of 0.5 ° C./min or 5 ° C./min under nitrogen gas flow and holding at 450 ° C. for 10 minutes. As a result, a laminate in which a PI film having a thickness of 18 μm was formed on a glass substrate was obtained. The adhesion between the glass substrate and the PI film in this laminate was evaluated according to the following criteria, and the evaluation results are shown in Table 1.

<Evaluation of adhesion>
If a uniform PI film can be formed on the glass substrate after thermosetting, “◎”, the PI film partially floats on the glass substrate after thermosetting, or there is at least one peeling point In the case, it was considered as "△" (there is a problem in practical use).
Further, the releasability between the glass substrate and the PI film in this laminate was evaluated based on the following criteria, and the evaluation results are shown in Table 1.

<Evaluation of peelability>
Make a cut with a cutter knife at 2.5 cm from the end of 4 sides of PI film, and stick the PI tape with adhesive to the end of the sample of PI film with a square cut of 15 cm on 1 side, PI tape When pulling up, if the PI film in close contact with the glass substrate can be easily peeled off, "◎", if there is a catch during peeling (ie, PI film on the glass substrate at part of the interface between PI film and glass substrate) When it adheres more firmly and inhibits peeling), it was set as "(triangle | delta)" (there is a problem in practical use).

Example 2
A PAA solution (A-3) was obtained in the same manner as Example 1, except that the blending amount of APMS was 75 ppm with respect to the mass of PAA. A-3 was evaluated in the same manner as in Example 1 for producing a laminate. The evaluation results are shown in Table 1.

Examples 3 and 4
Except that 3-aminopropyltriethoxysilane (APES molecular weight: 221.4) was used as the alkoxysilane, and the blending amount was a blending amount described in Table 1 as PAA solution (A-4 to A-5). A laminate was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 5
A laminate was prepared and evaluated in the same manner as in Example 1 except that PAA solution (A-6) was used in which the blending amount of APMS was 10 ppm with respect to the mass of PAA and the thickness of the PI film was 9 μm. . The evaluation results are shown in Table 1.

Example 6
A laminate was prepared and evaluated in the same manner as in Example 1 except that PAA solution (A-7) was used in which the blending amount of APMS was 95 ppm with respect to the mass of PAA, and the thickness of the PI film was 21 μm. . The evaluation results are shown in Table 1.

Examples 7 and 8
30 ppm and 75 ppm of APES with respect to the mass of PAA were added to B-1 and stirred to obtain uniform PAA solution (B-2) and PAA solution (B-3), respectively. A laminate was prepared and evaluated in the same manner as in Example 1 using these solutions. The evaluation results are shown in Table 1.

Examples 9 and 10
20 ppm and 40 ppm of APMS with respect to the mass of PAA were added to C-1 and stirred to obtain uniform PAA solution (C-2) and PAA solution (C-3), respectively. A laminate was prepared and evaluated in the same manner as in Example 1 using these solutions. The evaluation results are shown in Table 1.

Examples 11 to 13
A laminate was prepared and evaluated in the same manner as Example 1, except that A-6, A-7, and C-2 were used and the thickness of the PI film was 27 μm. The evaluation results are shown in Table 1.

Example 14
A homogeneous PAA solution (A-8) was obtained by adding 20 ppm of 3-ureidopropyltriethoxysilane (UPES molecular weight: 264) to A-1 and stirring. A laminate was prepared and evaluated in the same manner as in Example 1 using A-8. The evaluation results are shown in Table 1.

Example 15
80 ppm of AMPS was added to D-1 and stirred to obtain a uniform PAA solution (D-2). A laminate was prepared and evaluated in the same manner as in Example 1 using D-2. The evaluation results are shown in Table 1.

When the PAA solution used in Examples 1 to 15 was stored at 25 ° C. for 10 days, the viscosity change rate was less than 5% in all the solutions, and good storage stability was confirmed.

Comparative Examples 1 and 2
As an alkoxysilane, PAA solutions (A-9 and A-10) were used, in which 3-aminopropyltriethoxysilane (APES molecular weight: 221.4) was used and the blending amount was the blending amount described in Table 1. A laminate was prepared and evaluated in the same manner as in Example 1 except for the above. The evaluation results are shown in Table 1. The viscosity change rate after storage of A-9 and A-10 at 25 ° C. for 10 days was 5% or more for both PAA solutions.

Comparative Examples 3 to 5
A PAA solution (A-11 to A) was prepared using bis (3-trimethoxysilylpropyl) -N-methylamine (BTMM molecular weight: 355.6) as the alkoxysilane and the blending amount described in Table 1 A laminate was prepared and evaluated in the same manner as in Example 1 except that -13) was used. The evaluation results are shown in Table 1. The viscosity change rate after storing each of A-11 to A-13 at 25 ° C. for 10 days was all less than 5%.

Comparative Examples 6 to 8
Laminates were prepared and evaluated in the same manner as in Example 1 except that A-1, B-1 and C-1 containing no alkoxysilane were used as the PAA solution. The evaluation results are shown in Table 1. The viscosity change rate after storing each of A-1, B-1 and C-1 at 25 ° C. for 10 days was all less than 5%.

Comparative Example 9
A laminate was prepared and evaluated in the same manner as in Example 1 except that PAA solution (A-14) was used in which the blending amount of APES was 5 ppm with respect to the mass of PAA. The evaluation results are shown in Table 1. The viscosity change rate after storing A-14 at 25 ° C. for 10 days was less than 5%.

Comparative Example 10
A laminate was prepared and evaluated in the same manner as in Example 1 except that PAA solution (A-15) was used in which the blending amount of APMS was 5 ppm with respect to the mass of PAA and the thickness of the PI film was 10 μm. . The evaluation results are shown in Table 1. The viscosity change after A-15 was stored at 25 ° C. for 10 days was less than 5%.

In the case where the PAA solution of the present invention is used from the examples, the temperature raising rate at the time of heat curing is accelerated to 5 ° C./min by adjusting the compounding amount of the alkoxysilane compound according to the thickness of the PI film. However, it can be seen that good adhesion and peelability can be ensured. This is apparent from the comparison of Example 11 with Example 12, or the comparison of Example 9 with Example 13.
Also, in the comparison between Example 1 and Example 2 or the comparison between Example 3 and Example 4, even if the compounding amount of the alkoxysilane compound is changed to 30 ppm and 75 ppm, the adhesion and releasability are equal. The results of are obtained. In such a case, as described above, the blending amount of the alkoxysilane compound is more preferably 30 ppm, which is the smaller blending amount.
In addition, it is understood that the PAA solution of the present invention has good storage stability.

The PAA solution of the present invention can be suitably used as a solution for producing a flexible substrate comprising a PI film on which an electronic element is formed.

Claims (3)

It is a solution for coating to the glass substrate which consists of a polyamic acid (PAA), an amide system solvent, and an alkoxysilane compound, Comprising: The solution for coating to the glass substrate characterized by the following.
1) The content of the alkoxysilane compound is more than 5 ppm and less than 100 ppm based on the mass of PAA.
2) The molecular weight of the alkoxysilane compound is 100 or more and 300 or less. A method for producing a coating solution for a glass substrate comprising a polyamic acid (PAA), which is a polyimide (PI) precursor, an amide solvent and an alkoxysilane compound, wherein the PAA solution has a molecular weight of 100 or more, When compounding the alkoxysilane compound which is 300 or less, after setting the compounding quantity of the alkoxysilane compound to more than 5 ppm and less than 100 ppm with respect to PAA mass, the thickness of the PI film which aims at the compounding quantity of the alkoxysilane compound A method for producing a solution for coating on a glass substrate, characterized in that it is adjusted according to. In the method for forming a polyimide (PI) film on a glass substrate by coating the coating solution according to claim 1 onto a glass substrate and drying and then thermally curing, the temperature of the thermosetting is continuously raised. C., and the upper limit temperature at the time of thermal curing is 350.degree. C. or more and 500.degree. C. or less, and a method of producing a laminate comprising a PI film and a glass substrate.