TWI814695B - Polyimide-based varnish, method for manufacturing polyimide film using the same, and polyimide film - Google Patents

Abstract

An object of the present invention is to provide a polyimide-based varnish which can form a film having a good appearance and a good bending property. The polyimide-based varnish contains a polyimide-based polymer, a solvent and water, wherein when the polyimide-based polymer is used for forming a film having a thickness of 50μm, the total light transmittance of the film is 85% or more, and the yellowness index is 5 or less; the solvent is capable of dissolving the polyimide polymer, and the content of water is 0.60 to 4.5 mass% relative to the total mass of the polyimide varnish.

Description

Polyimide-based fluoride, a method for manufacturing a polyimide-based membrane using the polyimide-based fluoride, and a polyimide-based membrane

The present invention relates to polyimide-based verside, a method for manufacturing a polyimide-based membrane using the polyimide-based verside, and a polyimide-based membrane.

Conventionally, glass has been used as a material for base materials of various display components such as solar cells and displays, and for transparent components such as front panels. However, glass has the disadvantages of being easily broken and heavy. In addition, regarding the thinning, lightweighting, and flexibility of displays in recent years, there are insufficient materials. Therefore, a polyimide film is being studied as a transparent member of a flexible display in place of glass (for example, see Patent Document 1).

[Prior technical literature] [Patent Document]

Patent Document 1: U.S. Patent No. 8207256 Specification

However, conventional polyimide-based films may not be sufficient when used as display members or front panels of flexible devices. In addition, diaphragms used in display components or front panels are also required to be free from defects such as fish eyes, agglomerates, and streaks, and to have a good appearance.

The present invention is in view of such fact, and its object is to provide a polyimide-based fluoride that can form a diaphragm having good appearance and good flexibility, and to provide a method using this polyimide-based fluoride. A method for manufacturing a polyimide-based diaphragm and a polyimide-based diaphragm.

In order to achieve the above object, the present invention provides a polyimide-based fluorine water containing a polyimide-based polymer, a solvent and water, wherein the polyimide-based polymer is composed of the polyimide-based polymer. When the polymer forms a diaphragm with a thickness of 50 μm, the total light transmittance of the diaphragm is more than 85%, and the yellowness is less than 5; the solvent system can dissolve the polyimide polymer, and the water content is based on the polyimide polymer. Based on the total mass of acyl imine-based phenolic water, it is 0.60 to 4.5 mass %.

If the above-mentioned polyimide-based varicose is contained in water at the above-mentioned specific ratio, the appearance and flexibility of the polyimide-based membrane formed by using the polyimide-based varicose are excellent. . The reason why the appearance and flexibility of the polyimide-based membrane can be improved by the presence of water is not yet clear, but it is thought that the presence of moderate water during drying when forming the membrane can inhibit polyimide-based membranes. This is because the agglomeration of imine-based polymers forms a dense and uniform diaphragm. It is believed that through this, the causes of fish eyes, condensation, etc. can be suppressed. Problems such as poor appearance due to defects such as lumps and stripes, and cracking during bending.

Furthermore, in the above-mentioned polyimide-based fluoride, the polyimide-based polymer is used to form a film with a thickness of 50 μm, and the total light transmittance of the film is 85%. A transparent polyimide-based polymer with a yellowness of 5 or less. The total light transmittance of the above-mentioned diaphragm is preferably above 90%. Using such a transparent polyimide-based polymer, a highly transparent polyimide-based film can be obtained.

In the above-mentioned polyimide-based fluoride, the polyimide-based polymer preferably contains a halogen atom in the molecule, and the halogen atom is preferably a fluorine atom. Introducing halogen atoms, especially fluorine atoms, into the polyimide-based polymer helps reduce the yellowness of the resulting polyimide-based film. Here, the reduction of yellowness contributes to the improvement of transparency or appearance. In addition, polyimide-based polymers containing fluorine atoms have low hygroscopicity, so moisture can be sufficiently removed after the film is formed, making it easier to obtain a film with good appearance.

The above-mentioned polyimide-based fluoride may further contain silica particles. In this case, the strength of the polyimide-based film obtained can be improved, and good transparency of the film can be obtained.

The polyimide-based polyhydric acid containing the above-mentioned silica particles may further contain an alkoxysilane having an amine group. At this time, the effect of using silica particles to increase the strength of the polyimide-based membrane and the effect of obtaining good transparency of the membrane tend to be further enhanced.

The present invention also provides a polyimide-based membrane formed from the above-mentioned polyimide-based fluoride of the present invention. Such polyimide diaphragm The system will have excellent appearance and bendability.

The yellowness of the above-mentioned polyimide film is preferably 5 or less. In addition, the total light transmittance of the above-mentioned polyimide film is preferably 85% or more. The total light transmittance of polyimide-based diaphragms is preferably above 90%.

The present invention also provides a method for manufacturing a polyimide-based film, which includes the steps of coating the polyimide-based fluoride of the present invention on a substrate to form a coating film, and drying the coating film. The manufacturing method may further include a step of peeling the dried coating film from the base material. According to such a manufacturing method, a polyimide-based film containing a specific amount of moisture is used, and a polyimide-based film is formed through various steps such as coating, drying, and peeling off as needed, as described above. Especially when the coating film dries, the moisture will have a good influence on the structure formation process of the polyimide-based polymer, and a polyimide-based film with excellent appearance and flexibility can be obtained.

The present invention further provides a polyimide-based film produced by the above-described method for producing a polyimide-based film. Such a polyimide-based diaphragm has excellent appearance and flexibility.

According to the present invention, it is possible to provide a polyimide-based fluoride capable of forming a diaphragm having good appearance and good flexibility, and a polyimide-based diaphragm using the polyimide varnish. A manufacturing method and a polyimide-based diaphragm with good appearance and good flexibility.

Hereinafter, the present invention will be described in detail based on suitable embodiments.

[Polyimide based fenli water]

The polyimide-based fluorine water in this embodiment contains a polyimide-based polymer, a solvent that can dissolve the polyimide-based polymer, and water. The content of water is based on the polyimide-based polymer. Based on the total mass of the water, it is 0.60 mass% to 4.5 mass%.

The content of the polyimide-based polymer in the polyimide-based fluorine water can be 20 mass % or more, preferably 40 mass % or more, based on the total solid content in the phenylene glycol water.

In this specification, polyimide-based polymer means a polymer containing at least one of the repeating structural units represented by formula (PI), formula (a), formula (a') or formula (b). Among them, if the repeating structural unit represented by formula (PI) is the main structural unit of the polyimide-based polymer, it is preferable from the viewpoint of the strength and transparency of the film. The repeating structural unit represented by the formula (PI) is based on the total repeating structural units of the polyimide-based polymer, preferably 40 mol% or more, more preferably 50 mol% or more, and still more preferably The system has more than 70 mol%, the best series has more than 90 mol%, and the best series has more than 98 mol%.

G in the formula (PI) represents a tetravalent organic group, and A represents a divalent organic group. G ² in the formula (a) represents a trivalent organic group, and A ² represents a divalent organic group. G ³ in formula (a') represents a tetravalent organic group, and A ³ represents a divalent organic group. G ⁴ and A ⁴ in formula (b) each represent a divalent organic group.

In the formula (PI), the organic group of the tetravalent organic group represented by G (hereinafter, sometimes referred to as the organic group of G) includes: a non-cyclic aliphatic group, a cyclic aliphatic group, and an aromatic group. The base of a group composed of family bases. From the viewpoint of the transparency and flexibility of the polyimide film, G is preferably a tetravalent cyclic aliphatic group and a tetravalent aromatic group. Examples of the aromatic group include: monocyclic aromatic groups, condensed polycyclic aromatic groups, As well as non-condensed polycyclic aromatic groups in which aromatic groups are connected to each other directly or through bonding groups. From the viewpoint of suppressing the transparency and coloration of the polyimide-based film, the organic group of G may also be a cycloaliphatic group, a cycloaliphatic group having a fluorine-based substituent, or a fluorine-based substituent. A monocyclic aromatic group, a condensed polycyclic aromatic group having a fluorine-based substituent, or a non-condensed polycyclic aromatic group having a fluorine-based substituent. In this specification, the fluorine-based substituent means a group containing a fluorine atom. The fluorine-based substituent is preferably a fluorine group (fluorine atom, -F) and a perfluoroalkyl group, more preferably a fluorine group and a trifluoromethyl group.

More specifically, the organic group of G is, for example, selected from the group consisting of saturated or unsaturated cycloalkyl, saturated or unsaturated heterocycloalkyl, aryl, heteroaryl, aralkyl, alkaryl, heteroalkylaryl, and Any two of these groups (may also be the same) and these groups are connected to each other directly or through a bonding group. Examples of the bonding group include: -O-, an alkylene group having 1 to 10 carbon atoms, -SO ₂ -, -CO- or -CO-NR- (R represents a methyl group, an ethyl group, a propyl group, etc. with a carbon number of 1 to 3 alkyl groups or hydrogen atoms).

The carbon number of the tetravalent organic group represented by G is usually 2 to 32, preferably 4 to 15, more preferably 5 to 10, still more preferably 6 to 8. When the organic group of G is a cyclic aliphatic group or an aromatic group, at least one of the carbon atoms constituting these groups may be substituted with a heteroatom. Examples of heteroatoms include O, N, and S.

Specific examples of G include groups represented by the following formula (20), formula (21), formula (22), formula (23), formula (24), formula (25) or formula (26). The * in the formula represents the bonding bond. Z system in formula (26) represents a single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -Ar-O-Ar-, -Ar-CH ₂ - Ar-, -Ar- C(CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-. Ar represents an aryl group having 6 to 20 carbon atoms, and an example thereof is a phenylene group. At least one of the hydrogen atoms of these groups may be substituted with a fluorine-based substituent.

In the formula (PI), the organic group of the divalent organic group represented by A (hereinafter, sometimes referred to as the organic group of A) is selected from a non-cyclic aliphatic group, a cyclic aliphatic group and an aromatic group. A group of divalent organic radicals. The divalent organic group represented by A is preferably a divalent cyclic aliphatic group and a divalent aromatic group. Examples of the aromatic group include a monocyclic aromatic group, a condensed polycyclic aromatic group, and a non-condensed polycyclic aromatic group having two or more aromatic rings connected to each other directly or via a bonding group. base. From the viewpoint of improving the transparency of the polyimide film and suppressing coloration, it is preferable to introduce a fluorine-based substituent into the organic group of A.

More specifically, the organic group of A is, for example, selected from the group consisting of saturated or unsaturated cycloalkyl, saturated or unsaturated heterocycloalkyl, aryl, heteroaryl, aralkyl, alkaryl, heteroalkylaryl, And among them, there are any two groups (which may be the same) and these groups are connected to each other directly or through a bonding group. Examples of the hetero atom include O, N or S, and examples of the bonding group include -O-, an alkylene group having 1 to 10 carbon atoms, -SO ₂ -, -CO- or -CO-NR- (R represents Alkyl groups with 1 to 3 carbon atoms or hydrogen atoms such as methyl, ethyl, propyl, etc.).

The carbon number of the divalent organic group represented by A is usually 2 to 40, preferably 5 to 32, preferably 12 to 28, more preferably 24 to 27.

Specific examples of A include groups represented by the following formula (30), formula (31), formula (32), formula (33) or formula (34). The * in the formula represents the bonding bond. Z ¹ to Z ³ each independently represent a single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -SO ₂ -, -CO- or -CO-NR- (R represents A alkyl groups with 1 to 3 carbon atoms or hydrogen atoms such as ethyl group, propyl group, etc.). Among the following groups, it is preferred that Z ¹ and Z ² and Z ² and Z ³ are in the meta or para position with respect to each ring. In addition, it is preferable that Z ¹ and the terminal single bond, Z ² and the terminal single bond, and Z ³ and the terminal single bond are respectively in the meta or para position. An example of A, Z ¹ and Z ³ are -O-, and Z ² is -CH ₂ -, -C(CH ₃ ) ₂ - or -SO ₂ -. One or more hydrogen atoms of these groups may be substituted by fluorine-based substituents.

At least one of A and G, and the hydrogen atom constituting at least one of these hydrogen atoms, may be selected from the group consisting of a fluorine-based substituent, a hydroxyl group, a styrene group, an alkyl group having 1 to 10 carbon atoms, etc. At least one of the functional groups is substituted. Moreover, when the organic group of A and the organic group of G are respectively a cyclic aliphatic group or an aromatic group, at least one of A and G preferably has a fluorine substituent, and both A and G preferably have a fluorine substituent. The basis is better.

G ² in formula (a) is a trivalent organic group. This organic group can be selected from the same group as the G organic group in formula (PI) except for the trivalent point. Examples of G ² include any one of the four bonds of the group represented by formula (20) to formula (26), which are specific examples of G, being a substituent on a hydrogen atom. A ² in formula (a) can be selected from the same groups as A in formula (PI).

G ³ in formula (a') can be selected from the same groups as G in formula (PI). A ³ in formula (a') can be selected from the same groups as A in formula (PI).

G ⁴ in formula (b) is a divalent organic group. This organic group may be selected from the same group as the G organic group in formula (PI), except that it is a divalent group. Examples of G ⁴ include groups in which any two of the four bonds of the groups represented by the formulas (20) to (26) listed as specific examples of G are substituted for hydrogen atoms. A ⁴ in formula (b) can be selected from the same group as A in formula (PI).

The polyimide-based polymer contained in the polyimide-based film may also be a quasi-tetracarboxylic acid compound containing diamines and tetracarboxylic acid compounds (containing acid chloride compounds, tetracarboxylic dianhydride, etc.) Compound analogs) or at least one type of tricarboxylic acid compound (tricarboxylic acid compound analogs including acid chloride compounds, tricarboxylic anhydrides, etc.) are polymerized and condensed to obtain a condensation-type polymer. It is also possible to polycondensate a dicarboxylic acid compound (a compound containing an acid chloride compound or the like). The repeating structural unit represented by formula (PI) or formula (a') is usually derived from diamines and tetracarboxylic acid compounds. The repeating structural unit represented by formula (a) is usually derived from diamines and tricarboxylic acid compounds. The repeating structural unit represented by formula (b) is usually derived from diamines and dicarboxylic acid compounds.

Examples of the tetracarboxylic acid compound include aromatic tetracarboxylic acid compounds, alicyclic tetracarboxylic acid compounds, and non-cyclic aliphatic tetracarboxylic acid compounds. Two or more kinds of tetracarboxylic acid compounds may be used in combination. The tetracarboxylic acid compound is preferably tetracarboxylic dianhydride. Examples of tetracarboxylic dianhydride include aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride and non-cyclic aliphatic tetracarboxylic dianhydride.

From the viewpoint of the solubility of the polyimide-based polymer in solvents, the transparency and flexibility when forming the polyimide-based film, the tetracarboxylic acid compound is an alicyclic tetracarboxylic acid compound and an aromatic Tetracarboxylic acid compounds are preferred. From the viewpoint of transparency and coloration suppression of polyimide-based films Specifically, the tetracarboxylic acid compound is preferably an alicyclic tetracarboxylic acid compound having a fluorine-based substituent and an aromatic tetracarboxylic acid compound having a fluorine-based substituent, and an alicyclic tetracarboxylic acid compound is more preferred.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acid, alicyclic tricarboxylic acid, non-cyclic aliphatic tricarboxylic acid, and acid chloride compounds and acid anhydrides similar to these. The tricarboxylic acid compound is preferably aromatic tricarboxylic acid, alicyclic tricarboxylic acid, non-cyclic aliphatic tricarboxylic acid and acid chloride compounds similar to these. Two or more types of tricarboxylic acid compounds may be used in combination.

From the viewpoint of the solubility of the polyimide-based polymer in solvents, the transparency and flexibility when forming the polyimide-based film, the tricarboxylic acid compound is an alicyclic tricarboxylic acid compound or an aromatic Tricarboxylic acid compounds are preferred. From the viewpoint of the transparency of the polyimide-based film and the suppression of coloration, the tricarboxylic acid compound is an alicyclic tricarboxylic acid compound having a fluorine-based substituent and an aromatic tricarboxylic acid having a fluorine-based substituent. Compounds are better.

Examples of the dicarboxylic acid compound include aromatic dicarboxylic acids, alicyclic dicarboxylic acids, non-cyclic aliphatic dicarboxylic acids, and acid chloride compounds and acid anhydrides similar to these. The dicarboxylic acid compound is preferably aromatic dicarboxylic acid, alicyclic dicarboxylic acid, non-cyclic aliphatic dicarboxylic acid and acid chloride compounds similar to these. Two or more dicarboxylic acid compounds may be used in combination.

From the viewpoint of the solubility of the polyimide-based polymer in solvents, the transparency and flexibility when forming the polyimide-based film, the dicarboxylic acid compound is an alicyclic dicarboxylic acid compound and an aromatic Dicarboxylic acid compounds are preferred. From the viewpoint of the transparency of the polyimide-based film and the suppression of coloration, the dicarboxylic acid compound is an alicyclic dicarboxylic acid having a fluorine-based substituent. Acid compounds and aromatic dicarboxylic acid compounds having a fluorine-based substituent are preferred.

Examples of diamines include aromatic diamines, alicyclic diamines, and aliphatic diamines. Two or more types of diamines may be used in combination. From the viewpoint of the solubility of the polyimide-based polymer in solvents, the transparency and flexibility when forming the polyimide-based film, the diamines are alicyclic diamines and have fluorine-based substituents. Aromatic diamines are preferred.

If such a polyimide-based polymer is used, it is easy to obtain a film that has particularly excellent flexibility, high light transmittance (for example, 85% or more, preferably 88% or more for light of 550 nm), and low yellow color. A polyimide-based film with high density (YI value, for example, 5 or less, preferably 3 or less) and low haze (for example, 1.5% or less, preferably 1.0% or less).

The polyimide-based polymer may also be a copolymer containing a plurality of different types of the above-mentioned repeating units. The weight average molecular weight of the polyimide-based polymer is usually 10,000 to 500,000. The weight average molecular weight of the polyimide-based polymer is preferably 50,000 to 500,000, more preferably 70,000 to 400,000. The weight average molecular weight is a standard polystyrene converted molecular weight measured by GPC. Polyimide-based polymers with a large weight-average molecular weight tend to have high flexibility. However, when the weight-average molecular weight of polyimide-based polymers is too large, the viscosity of the polyimide-based polymer will increase, and the processability will deteriorate. tendency to decrease.

The polyimide-based polymer may also contain halogen atoms such as fluorine atoms introduced through the above-mentioned fluorine-based substituent or the like. Because the polyimide-based polymer contains halogen atoms, the elastic modulus of the polyimide-based diaphragm can be improved and the yellowness can be reduced. This can prevent scratches on the polyimide-based diaphragm. and crepe, etc., and can improve the transparency of the polyimide film. As the halogen atom, a fluorine atom is preferred. The content of halogen atoms in the polyimide-based polymer is preferably 1 to 40 mass%, and more preferably 1 to 30 mass% based on the total mass of the polyimide-based polymer.

When a polyimide-based polymer film (layer) with a thickness of 50 μm is composed of the polyimide-based polymer, the total light transmittance of the polyimide-based polymer film is 85% or more, and , the polyamide-based polymer film is preferably a transparent polyimide-based polymer with a yellowness (YI value) of 10 or less. The above-mentioned total light transmittance is preferably above 90%. The above-mentioned yellowness is preferably 5 or less. Using such a transparent polyimide-based polymer, a highly transparent polyimide-based film can be obtained. In addition, the total light transmittance of the above-mentioned polyimide-based polymer film is preferably 91% or more, and more preferably 92% or more. A yellowness of 3 or less is better, and a yellowness of 2.5 or less is particularly good. Here, the polyimide-based polymer film can be formed by coating and drying the polyimide-based polymer dissolved in a solvent. The total light transmittance of the polyimide-based polymer film can be determined in accordance with JIS K 7105:1981. The yellowness YI of the polyimide-based polymer film can be determined according to JIS K 7373:2006.

烷、丙酮、環戊酮、二甲基亞碸、二甲苯以及此等的組合。 In the polyimide-based phenol water, the solvent system is not particularly limited as long as it can dissolve the amide-based polymer. Examples thereof include N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), γ-butyrolactone (GBL), N-methylpyrrolidone (NMP), ethyl acetate, methyl ethyl ketone (MEK), tetrahydrofuran, 1,4-bis

alkanes, acetone, cyclopentanone, dimethylstyrene, xylene and combinations thereof.

Polyimide is based on phenolic water and contains water in addition to the above solvents. The water content (moisture content) of the polyimide-based fentanyl water is 0.60 to 4.5 mass%, preferably 0.7 to 4.0 mass%, based on the total mass of the polyimide-based fentanyl water. 1.0 to 4.0% by mass is more preferred. The lower limit of the water content is preferably 1.5% by mass, more preferably 2.0% by mass, and particularly preferably 2.5% by mass. Furthermore, the upper limit of the water content is more preferably 3.5% by mass.

When the polyimide-based fentanyl water contains silica particles, the moisture content in the polyimide-based fentanyl water shall be 1.5 to 3.5% by mass based on the total mass of the polyimide-based fentanyl water. Preferably, 2.5 to 3.5 mass % is more preferred, and 2.5 to 3.0 mass % is particularly preferred. When a diaphragm is produced using such a polyimide-based fluoride, a polyimide-based diaphragm with excellent flexibility tends to be easily obtained.

When the moisture content in the polyimide-based polymer is within the above range, the presence of water can have a good influence on the structure formation process of the polyimide-based polymer, and the appearance and flexibility of the formed membrane are good. . The moisture content of polyimide-based fluoride water can be measured by the Karl Fischer titration method. The measurement by the Karl Fischer method was performed in accordance with JIS K 0068:2001. Reagents for titration are those that do not cause side effects with the solvent. Examples of suitable combinations of anolyte and catholyte in ketone solvents such as N,N-dimethylacetamide include Coulomat AK manufactured by Sigma Aldrich and Coulomat CG-K manufactured by Sigma Aldrich. . As a measuring device, a 831KF coulometer manufactured by Metrohm Co., Ltd. or the like can be used.

From the viewpoint of improving the strength of the obtained polyimide-based film, the polyimide-based fluoride may further contain inorganic particles. Examples of the inorganic particles include particles containing silicon atoms, and examples of the particles containing silicon atoms include silicon dioxide particles. Other examples of inorganic particles include titanium dioxide particles, alumina particles, and zirconium oxide particles.

The average primary particle diameter of the inorganic particles is usually 100 nm or less. When the average primary particle size of the inorganic particles is 100 nm or less, the transparency of the film tends to be improved. The primary particle size of inorganic particles can be determined by determining the directional diameter using a transmission electron microscope (TEM). The average primary particle diameter can be determined by measuring the primary particle diameters at 10 points through TEM observation and obtaining the average value thereof.

In the polyimide-based phenol water, the blending ratio of the polyimide-based polymer and the inorganic particles, in terms of mass ratio, is usually 1:9 to 10:0, preferably 3:7 to 10:0, and 3:7 to 8:2 is preferred, and 3:7 to 7:3 is even more preferred. When the blending ratio of the polyimide-based polymer and the inorganic particles is within the above range, the transparency and mechanical strength of the polyimide-based film tend to be improved.

When the polyimide-based fluoride contains inorganic particles, in the resulting polyimide-based film, the inorganic particles may be bonded to each other through molecules having siloxane bonds (-SiOSi-).

When the polyimide-based fluoride contains inorganic particles, the fluoride may also contain metal alkoxides such as alkoxysilane in order to improve the stability of the solution. Preferable is an alkoxysilane having an amine group. Especially when the polyimide-based fluoride contains silica particles as inorganic particles, it may further contain Alkoxysilane having an amine group tends to improve the dispersibility of silica particles, improve the strength of the polyimide film, and further improve the transparency of the film.

The amount of metal alkoxide added may be 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the inorganic particles.

The polyimide-based fluoride may further contain other components as long as the transparency and flexibility of the obtained polyimide-based film are not impaired. Examples of other components include antioxidants, release agents, stabilizers, coloring agents such as bluing agents, flame retardants, lubricants, thickeners, smoothing agents, and the like. In the obtained polyimide-based film sheet, the content of the above-mentioned other components, based on the total mass of the polyimide-based film sheet, is preferably more than 0 mass % and not more than 20 mass %, and is preferably more than 0 mass %. Those with 10% by mass or less are more preferred.

The polyimide-based fluorescein may contain organic silicon compounds such as tetraethyl orthosilicate (TEOS) and other 4-stage alkoxysilanes, and sesquisiloxane derivatives.

From the viewpoint of storage stability and coating properties, the solid content concentration of the polyimide-based phenol water is preferably 5 to 30 mass %, and more preferably 10 to 25 mass %.

(polyimide diaphragm)

The polyimide-based diaphragm of this embodiment is a diaphragm formed using the above-mentioned polyimide-based vanillin.

The thickness of the polyimide diaphragm can be appropriately adjusted according to the use, but it is usually 10 to 500 μm, preferably 15 to 200 μm. 20 to 100 μm is better.

According to JIS K 7105:1981, the total light transmittance of this polyimide-based diaphragm is preferably 85% or more, and more preferably 90% or more. In addition, according to JIS K 7105:1981, the haze of this polyimide-based film is preferably 1 or less, and more preferably 0.9 or less. In addition, according to JIS K 7373:2006, the yellowness YI of this polyimide film is preferably 5 or less, and more preferably 3 or less. Polyimide films with such optical properties are suitable for use as optical films for smartphones and tablets that require high visibility.

(manufacturing method)

Next, an example of the method for producing the polyimide-based fluoride of the present embodiment and the method for producing the polyimide-based membrane sheet of the present embodiment will be described.

The polyimide-based Vanli Water System uses a well-known synthesis method of polyimide-based polymers to dissolve the polymerized polyimide-based polymers that are soluble in the solvent into the solvent, and further mixes water and If necessary, the above-mentioned inorganic particles, metal alkoxide, and other components are added and mixed to prepare. When adding inorganic particles to the polyimide-based fentanyl water, the inorganic particles can be uniformly dispersed in the polyimide-based fentanyl water by stirring and mixing using a known stirring method. Examples of solvents are as described above. As the polyimide-based polymer, as long as it is a polyimide-based polymer that is soluble in a solvent, as mentioned above, aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, acyclic tetracarboxylic dianhydride, and acyclic dianhydride can be used. One or more types of tetracarboxylic dianhydrides such as aliphatic tetracarboxylic dianhydrides, and one type of diamines such as aromatic diamines, alicyclic diamines, and non-cyclic aliphatic diamines Or obtained by the condensation of 2 or more kinds of polymers. Tetracarboxylic dianhydride and Diamines preferably have fluorine-based substituents introduced therein.

It is not necessary to add water to the preparation of polyimide-based fenli water. That is, when the prepared polyimide-based polymers, solvents, inorganic particles, metal alkoxides, or other components absorb moisture and contain moisture, the moisture content of the polyimide-based solvent is determined by the water. As long as it is within the range stipulated in this embodiment, water may not be added when preparing the polyimide-based phenol water. For example, when the preparation of polyimide-based vinyl water is carried out in an environment with a certain degree of humidity, even if no water is added, water may be appropriately absorbed into the polyimide-based vinyl water.

When the polyimide-based vanadium water contains inorganic particles, since the vanadium water contains water, it also has the advantage of inhibiting the gelation of the vanadium water. Therefore, the effect of having a moderate amount of water in the polyamide water is particularly noticeable when the polyimide-based vinyl water contains inorganic particles, and the polyimide-based film is less likely to gel due to the vinyl water. This results in poor appearance and a highly flexible diaphragm.

The prepared polyimide is based on fluoride, and is then coated on the PET substrate, SUS conveyor belt, or glass substrate through a well-known roller-to-roller or batch method to form a coating film. This coating film is dried to become a polyimide film.

The coating film is dried by evaporating the solvent and water at a temperature of 50 to 350°C, in a suitable inert gas environment or under reduced pressure. The drying of the coating film can be carried out in a multi-stage manner by changing the temperature conditions. At this time, some temperatures can also be increased in the later stages. By drying the coating film in multiple stages in this way, the speed of solvent and water evaporation can be controlled, and the structure of the polyimide-based polymer can be improved. At the same time, the aggregation of polyimide-based polymers can be further suppressed, and the appearance and flexibility of the obtained diaphragm can be further improved.

In addition, the coating film may be dried after being peeled off from the base material. That is, in the first drying, the coating film can be dried on the base material and then peeled off from the base material, and in the second drying, it can be further dried. The second drying system can be performed by attaching a metal frame to the coating film peeled off from the base material, or by using a known expander equipment. The second drying system can be performed at a higher temperature than the first drying. For example, the first drying can be performed at 50 to 190°C, and the second drying can be performed at 190 to 350°C. Furthermore, the first drying and the second drying may be performed in multiple stages by changing the temperature conditions respectively.

(use)

Such a polyimide-based film can be used as a component of a flexible display because it has excellent appearance and flexibility. For example, it can be used as a front panel (window film) for surface protection of a flexible display.

Furthermore, it may be a laminate in which various functional layers such as an ultraviolet absorbing layer, a hard coat layer, an adhesive layer, a hue adjustment layer, and a refractive index adjustment layer are added to the polyimide film.

[Example]

Hereinafter, although the present invention will be further explained in detail through Examples and Comparative Examples, the present invention is not limited to the following Examples.

[Example 1]

(Synthesis of polyimide)

In a nitrogen-substituted polymerization tank, put the compound represented by formula (1), The compound represented by formula (2), the compound represented by formula (3), a solvent (γbutyrolactone and dimethylacetamide), and a catalyst. The feeding amounts are 75.0 g of the compound represented by the formula (1), 36.5 g of the compound represented by the formula (2), 76.4 g of the compound represented by the formula (3), 438.4 g of γ-butyrolactone, and dimethyl ethyl 313.1g of amide and 1.5g of catalyst. The molar ratio between the compound represented by formula (2) and the compound represented by formula (3) is 3:7, and the total of the compound represented by formula (2) and the compound represented by formula (3) is equal to the molar ratio of the compound represented by formula (1) ) The molar ratio of the compound shown is 1.00:1.02.

After stirring the mixture in the polymerization tank and dissolving the raw materials in the solvent, the temperature was raised to 100°C while stirring the mixture. Thereafter, the temperature was raised to 200°C without stirring, and the temperature was maintained at 200°C for 4 hours to polymerize the polyimide. Moreover, during this heating, water in the liquid is removed. Thereafter, polyimide is obtained by purification and drying.

(Preparation of polyimide-based fenli water)

Next, a γ-butyrolactone solution of polyimide with a concentration adjusted to 20% by mass, and silica with a solid concentration of 30% by mass were dispersed in γ-butyrolactone. A dispersion of particles and a dimethylacetamide solution of an alkoxysilane having an amine group were mixed, and the mixture was stirred for 30 minutes to prepare polyimide-based fluoride.

Here, the mass ratio of silica and polyimide is 60:40, and the amount of alkoxysilane having an amino group per 100 parts by mass of the total of silica and polyimide is 1.67 mass. share. The amounts of these silica, polyimide, and alkoxysilane having an amino group are the amounts of the solid content excluding the solvent (hereinafter, the same applies). The moisture content of the obtained polyimide-based valerian water was measured by the Karl Fischer titration method. The result was 0.80 mass%. The moisture content of the polyimide-based phenol water was measured using a 831KF coulometer manufactured by Metrohm Corporation. The measurement was performed in accordance with JIS K0068:2001, using Coulomat AK manufactured by Sigma Aldrich Co., Ltd. as the anolyte, and Coulomat CG-K manufactured by Sigma Aldrich Co., Ltd. as the catholyte.

(Production of polyimide-based diaphragm)

Polyimide-based fluoride is coated on a polyethylene terephthalate substrate (PET substrate), heated at 50°C for 30 minutes, and then heated at 140°C for 10 minutes, then peeled off from the PET substrate and mounted on a metal On the frame, it was further heated at 210°C for 1 hour to obtain a polyimide film with a thickness of 50 μm.

[Example 2]

Except when preparing the polyimide-based varicose water, 10 parts by mass of water is added to the total of 100 parts by mass of silica and polyimide-based varnishing water so that the moisture content of the polyimide-based varnishing water becomes 2.69 Except for mass %, the rest are related to The same operation as in Example 1 was carried out, and the polyimide-based varicose was prepared and the polyimide-based varicose was used to prepare a polyimide-based membrane.

[Example 3]

When preparing polyimide-based valeric acid, in addition to dimethylacetamide and γbutyrolactone of the silica particle dispersion, a dehydration solvent (dehydrated dimethylacetamide and dehydrated γbutyrolactone) is used. Except for the ester), the same operations were carried out as in Example 2 to prepare the polyimide-based varicose water and use the polyimide-based varicose water to prepare the polyimide-based membrane. When the moisture content of the prepared polyimide-based phenol water was measured by the Karl Fischer method, it was 2.45% by mass.

[Example 4]

Polyimide "KPI-MX300F (100)" manufactured by Kawamura Sangyo Co., Ltd. was dissolved in dimethylacetamide to prepare a solution with a concentration of 16% by mass (polyimide based on fluoride). After further adding a small amount of water, the moisture content was evaluated, and the moisture content of the polyimide-based phenolic water was 1.22% by mass. Except using this polyimide-based fluoride, the other procedures are the same as in Example 1 to prepare a polyimide-based membrane.

[Example 5]

A 20 mass% gamma butyrolactone solution of the polyimide fluoride "Neoprim C6A20" manufactured by Mitsubishi Gas Chemical Co., Ltd. was mixed with silica particles having a solid concentration of 30 mass% dispersed in gamma butyrolactone. The dispersion, the dimethylacetamide solution of the alkoxysilane having an amine group, and water were stirred for 30 minutes to prepare polyimide-based fluoride. The added amount of water is 10 parts by mass relative to 100 parts by mass of the total of silica and polyimide.

Here, the mass ratio of silica to polyimide is 55:45, and the amount of alkoxysilane having an amino group is 1.67 with respect to 100 parts by mass of the total of silica and polyimide. parts by mass. The moisture content of the polyimide-based fluorine water is 2.56% by mass. Except using this polyimide-based fluorine water, the other procedures are the same as in Example 1 to prepare a polyimide-based membrane.

[Comparative example 1]

When preparing polyimide-based fluoride, in addition to dimethylacetamide and γbutyrolactone of the silica particle dispersion, a dehydration solvent (dehydrated dimethylacetamide and dehydrated γbutyrolactone) is used. Except for the ester), the same operations as in Example 1 were carried out to prepare the polyimide-based varicose and to prepare the polyimide-based membrane using the polyimide-based varicose. The moisture content of the prepared polyimide-based fluorine water was 0.55% by mass when measured by the Karl Fischer method. In addition, the obtained polyimide-based membrane sheet had many agglomerates, and compared with the membrane sheet of Example 1, its appearance was poor.

[Comparative example 2]

When preparing the polyimide-based versified water, except that the mixing ratio of water is adjusted so that the moisture content of the polyimide-based versified water becomes 4.59% by mass, the remaining operations are carried out in the same manner as in Example 2, and the polyimide-based versified water is prepared. Preparation of polyimide-based fluoride and production of polyimide-based diaphragm using the polyimide-based fluoride. The obtained polyimide-based film had low transparency and was hazy. Furthermore, when the polyimide-based fluorohydrin was observed after being left for one day, the liquid was separated into two phases.

[Comparative example 3]

When preparing the polyimide-based versified water, except that the mixing ratio of water was adjusted so that the moisture content of the polyimide-based versified water became 6.48% by mass, the remaining operations were carried out in the same manner as in Example 1. Preparation of polyimide-based parabens and the production of polyimide-based membranes using this polyimide-based parabens. However, a lot of solid matter will precipitate when preparing the polyimide-based parabens, and a uniform film must be produced. Film is having difficulty.

[Comparative example 4]

Prepare a solution in which polyimide "KPI-MX300F (100)" manufactured by Kawamura Sangyo Co., Ltd. is dissolved in dimethylacetamide with a concentration of 16% by mass, and water is added to prepare a polyimide with a water content of 10% by mass. The amine series is all water. Except for using this polyimide-based fluoride, the rest was the same as in Example 1, and an attempt was made to make a polyimide-based membrane. However, solid matter precipitated when preparing the polyimide-based fluoride. It is difficult to produce a uniform film.

[Comparative example 5]

When preparing the polyimide-based fentanyl water, the same operation as in Example 5 was performed except that water was added to adjust the water content to 10% by mass, and the polyimide-based fentanyl water was prepared. Except for using this polyimide-based fluoride, the rest was the same as in Example 1. Although an attempt was made to make a polyimide-based membrane, solid matter precipitated during the preparation of the polyimide-based fluoride. It is difficult to produce a uniform diaphragm.

[Evaluation of diaphragm appearance]

The appearance of the polyimide-based films obtained in the Examples and Comparative Examples was visually observed. Those with no defects such as fish eyes, agglomerates, and streaks were regarded as "A". Those with fish eyes, agglomerates, and streaks were seen. Those with defects such as stripes are classified as "B", If a uniform film cannot be formed, or even if a film can be formed, it is uneven and foggy, it is evaluated as "C". The results are shown in Table 1. For films whose appearance is evaluated as "C", the yellowness and total light transmittance cannot be measured.

[Measurement of yellowness (YI value)]

The yellowness (Yellow Index: YI value) of the polyimide-based films obtained in Examples and Comparative Examples was measured using a UV-visible-near-infrared spectrophotometer V-670 manufactured by JASCO Corporation. After measuring the background without a sample, place the polyimide film on the sample holder, measure the transmittance of light from 300 to 800 nm, and obtain three stimulation values (X, Y, Z). The YI value is calculated based on the following formula. The results are shown in Table 1.

YI=100×(1.2769X-1.0592Z)/Y

[Measurement of total light transmittance]

According to JIS K 7105:1981, the total light transmittance of the polyimide-based films obtained in the examples and comparative examples was measured using the fully automatic direct-reading haze computer HGM-2DP manufactured by Suga Testing Machine Co., Ltd. Rate. The results are shown in Table 1.

[Evaluation of bendability]

The bending properties of the polyimide-based films obtained in Examples and Comparative Examples were evaluated based on the following criteria. When folding the film by hand, only the crease is formed and there is no abnormality around the crease, it is classified as "A". The periphery of the crease becomes white, etc., and the appearance around the crease changes. "B", if the fold is partially broken, it will be evaluated as "C".

Claims (12)

A kind of polyimide-based fluoride, which is a polyimide-based fluoride containing a polyimide-based polymer, a solvent, and water, wherein the polyimide-based polymer is composed of the polyimide-based polymer When the imine-based polymer forms a diaphragm with a thickness of 50 μm, the total light transmittance of the diaphragm is more than 85%, and the yellowness is less than 5; if the solvent system can dissolve the polyimide-based polymer, the water content Based on the total mass of the polyimide-based fluoride, it is 0.60 to 4.5% by mass, and the solid content concentration of the aforementioned polyimide-based fluoride is 5 to 25% by mass. For example, the polyimide-based polymer described in item 1 of the patent application includes halogen atoms in the molecule. The polyimide described in item 2 of the patent application is a polyimide, in which the halogen atom is a fluorine atom. For example, the polyimide described in any one of items 1 to 3 of the patent application is a polyimide, which further contains silicon dioxide particles. For example, in the polyimide-based polyhydric acid described in item 4 of the patent application, the blending ratio of the polyimide-based polymer and the silicon dioxide particles, in terms of mass ratio, is 3:7 to 8:2. For example, the polyimide described in item 5 of the patent application is a polyimide, which further contains an alkoxysilane with an amine group. A polyimide-based diaphragm, which is formed from the polyimide-based fluoride described in any one of items 1 to 6 of the patent application scope, and has a film thickness of 20 to 100μm. The polyimide film as described in Item 7 of the patent application, wherein the yellowness is 5 or less. For example, the polyimide film described in item 7 or 8 of the patent application has a total light transmittance of more than 85%. A method for manufacturing a polyimide-based film, which includes the following steps: coating the polyimide-based vanillin described in any one of items 1 to 6 of the patent application on a base material to form The steps for applying the film are the same as those for drying the film. The manufacturing method of the polyimide film sheet described in claim 10 further includes the step of peeling off the dried coating film from the base material. A polyimide-based film is produced by the method for manufacturing a polyimide-based film described in Item 10 or 11 of the patent application.