KR102111606B1 - Polyimide precursor composition, prepataion method of polyimide film and polyimide film using the same - Google Patents

Abstract

The present invention relates to a polyimide precursor composition, a method for producing a polyimide film using the same, and a polyimide film.

Description

POLYIMIDE PRECURSOR COMPOSITION, PREPATAION METHOD OF POLYIMIDE FILM AND POLYIMIDE FILM USING THE SAME

The present invention relates to a polyimide precursor composition, a method for producing a polyimide film using the same, and a polyimide film.

Polyimide resin is a polymer having an amorphous structure, and exhibits excellent heat resistance, chemical resistance, electrical properties, and dimensional stability due to its rigid chain structure. These polyimide resins are widely used as electrical / electronic materials.

However, the polyimide resin has a limitation of having a dark brown color due to formation of a charge transfer complex (CTC) of π electrons present in the imide chain, and thus has many limitations in use.

As a method for resolving the above limitation and obtaining a colorless transparent polyimide resin, a method of limiting the movement of π electrons by introducing a strong electron withdrawing group such as a trifluoromethyl (-CF ₃ ) group; A method of reducing formation of the CTC by introducing a sulfone (-SO _2- ) group, an ether (-O-) group, etc. into the main chain to form a curved structure; Alternatively, a method of inhibiting the formation of a resonance structure of π electrons by introducing an aliphatic ring compound has been proposed.

However, the polyimide resin according to the above proposals is difficult to exhibit sufficient heat resistance by a curved structure or an aliphatic cyclic compound, and the film produced using this still has limitations showing poor mechanical properties.

Conventionally, as a method for improving the mechanical properties of polyimide, there is a method of additionally introducing a monomer having a rigid structure, but in this case, the packing of the polymer chain is improved, resulting in a yellowness (YI) increase due to CTC. have.

In addition, recently, a method of improving the mechanical properties of the polyimide resin in the same structure through an additional crosslinking process has been proposed. In this case, due to the high reactivity of the crosslinking agent present in the coating solution composition, a crosslinking reaction occurs at room temperature immediately after the addition of the crosslinking agent, thereby increasing the viscosity of the coating solution, thereby causing a problem of deteriorating the coating property of the composition.

The present invention is to provide a polyimide precursor composition capable of manufacturing a polyimide film capable of exhibiting excellent mechanical properties, and having excellent process workability.

The present invention is to provide a method for producing a polyimide film using the polyimide precursor composition.

In addition, the present invention is to provide a polyimide film made of the composition for coating the polyimide.

In the present specification, a polyamic acid including a unit structure derived from an aromatic diamine-based monomer and a unit structure derived from an aromatic diamine-based monomer; And an azide-based crosslinking agent comprising at least one of the compounds represented by the following Chemical Formulas 1 to 4, to provide a polyimide precursor composition:

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

.

.

The azide-based crosslinking agent may be included in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the polyamic acid.

The aromatic diamine-based monomer is 2,2'-bis (trifluoromethyl) -4,4'-biphenyldiamine (2,2'-bis (trifluoromethyl) -4,4'-biphenyldiamine), 4, 4'-diaminodiphenyl sulfone, 4,4 '-(9-fluorenylidene) dianiline, 4,4'-(9-fluorenylidene) dianiline, bis (4 -(4-aminophenoxy) phenyl) bis (4- (4-aminophenoxy) phenyl) sulfone), 2,2 ', 5,5'-tetrachlorobenzidine (2,2', 5,5'- tetrachlorobenzidine), 2,7-diaminofluorene, 4,4-diaminooctafluorobiphenyl, m-phenylenediamine, p -Phenylenediamine, 4,4'-oxydianiline, 2,2'-dimethyl-4,4'-diaminobiphenyl (2,2'- dimethyl-4,4'-diaminobiphenyl), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (2,2-bis [4- (4-aminophenoxy) phenyl] propane), 1,3 -Bis (4-aminophenoxy) benzene (1,3-bis (4-aminophenoxy) benzene) and 4,4'-dia No-benzamide may be at least one selected from the group consisting of fluoride (4,4'-diaminobenzanilide) not.

The aromatic dianhydride-based monomer, 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, BPDA), 2,2 -Bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (2,2-bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 6FDA), benzophenone tetracarboxylic dianhydride (benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, oxydiphthalic anhydride, cyclobutane tetracarboxylic dihydride (cyclobutane tetracarboxylic dianhydride), cyclopentane tetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) sulfone diane Deurayideu may be at least one selected from the group consisting of (bis (3,4-dicarboxyphenyl) sulfone dianhydride).

The viscosity of the composition may be 1,000 to 200,000 cps.

In the present specification, a step of forming a coating layer by applying the above-described polyimide precursor composition to a substrate, and heating the coating layer to 200 to 300 ° C; includes a method for manufacturing a polyimide film.

The heating step may be performed for 1 to 60 minutes.

In addition, the present specification also provides a polyimide film formed of the aforementioned polyimide precursor composition.

The polyimide film may have a thickness of 10 to 150 μm.

The polyimide film may have a pencil hardness of F or higher according to ASTM E313 based on a film thickness of 100 ± 10 μm.

The polyimide film may have a transmittance at 550 nm of 85% or more when measuring transmittance with a UV spectrometer based on a film thickness of 100 ± 10 μm.

According to the polyimide precursor composition of the present invention, it is possible to provide a polyimide film that is colorless and transparent and has excellent mechanical properties.

According to the production method of the polyimide film of the present invention, it is possible to improve the mechanical strength of the film without deteriorating workability upon application of the composition.

1 is a FR-IR graph before and after curing of a composition according to an embodiment of the present invention for confirming a crosslinking reaction of an azide crosslinking agent.
2 is a graph measuring the mechanical properties of the film according to Examples and Comparative Examples of the present invention.

The present invention is a polyamic acid comprising a unit structure derived from an aromatic diamine-based monomer and a unit structure derived from an aromatic dianhydride-based monomer; And an azide-based cross-linking agent having a specific structure.

Hereinafter, a polyimide precursor composition according to a specific embodiment of the present invention, a method for manufacturing the polyimide film using the same, and a polyimide film will be described in more detail.

The terminology used herein is only used to describe exemplary embodiments, and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, the terms "comprises", "haves" or "have" are intended to indicate the presence of implemented features, numbers, steps, elements or combinations thereof, one or more other features or It should be understood that the existence or addition possibilities of numbers, steps, elements, or combinations thereof are not excluded in advance.

The present invention can be applied to various changes and may have various forms, and specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosure form, and it should be understood that it includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

<Polyimide precursor composition>

Conventionally, in the case of a crosslinking agent used to improve the mechanical properties of a polyimide film, due to high reactivity, a crosslinking reaction occurs at room temperature immediately after the introduction of the crosslinking agent to increase the viscosity of the coating solution, thereby lowering the coating properties of the composition There was.

Accordingly, the present inventor has developed a composition for improving the mechanical properties of the film by causing a crosslinking reaction between polyimide copolymers under the curing process conditions of the film, without a separate crosslinking process under the conditions of room temperature at which the composition is stored.

The azide crosslinking agents represented by the following Chemical Formulas 1 to 4 are components that improve the mechanical properties of the film by crosslinking reaction between the imidized polyimide copolymer in the curing step of the coating after coating the composition on the substrate.

[Formula 1]

.

.

[Formula 2]

[Formula 3]

[Formula 4]

.

.

The azide-based crosslinking agent represented by Chemical Formulas 1 to 4 may have a temperature range of 200 to 300 ° C, and preferably 220 to 280 ° C. The temperature range may include a temperature range of the curing process of the film, and accordingly, a crosslinking reaction is not performed at room temperature, and a crosslinking reaction is performed in the curing process of the film to improve mechanical properties of the film.

The azide-based compound may be included in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of polyamic acid, and preferably 0.05 to 1 part by weight. When included in the content range, a lower yellow index (Y.I.), high visible light transmittance, and improved mechanical strength can be simultaneously secured. When the azide compound is contained in an amount of less than 0.01 part by weight, it is difficult to realize the effect in a trace amount, and when it is included in an amount exceeding 5 parts by weight, the yellow index (YI) of the film rises, and the flexibility of the film slightly decreases Can be.

In the polyimide precursor composition according to an embodiment of the present invention, the polyamic acid includes a unit structure derived from an aromatic diamine-based monomer and a unit structure derived from an aromatic dianhydride-based monomer, and the aromatic diamine-based monomer And aromatic dianhydride-based monomers. Thereafter, the polyamic acid (PAA) is made of a polyimide copolymer through an imidization reaction, and the imidization reaction may be performed by thermal imidization or chemical imidization. Compounds such as acetic anhydride and pyridine may be used in the chemical imidization reaction.

In the present invention, the polyamic acid may be an azide-based crosslinking agent introduced at the end of the polyamic acid through mixing with an azide-based crosslinking agent, and thereafter, an imidization reaction simultaneously with heating for the crosslinking reaction of the azide-based crosslinking agent It may be through. That is, the thermal imidization of the polyamic acid and the crosslinking reaction between the polyimide copolymers occur through the azide-based crosslinking agent through the heating, thereby improving the mechanical properties of the film. Here, chemical imidization may be performed simultaneously with thermal imidation of the polyamic acid.

As the aromatic diamine-based monomer, 2,2'-bis (trifluoromethyl) -4,4'-biphenyldiamine (2,2'-bis (trifluoromethyl) -4,4'-biphenyldiamine), 4 , 4'-diaminodiphenyl sulfone, 4,4 '-(9-fluorenylidene) dianiline, 4,4'-(9-fluorenylidene) dianiline, bis ( 4- (4-aminophenoxy) phenyl) bis (4- (4-aminophenoxy) phenyl) sulfone, 2,2 ', 5,5'-tetrachlorobenzidine (2,2', 5,5 ' -tetrachlorobenzidine), 2,7-diaminofluorene, 4,4-diaminooctafluorobiphenyl, m-phenylenediamine, p-phenylenediamine, 4,4'-oxydianiline, 2,2'-dimethyl-4,4'-diaminobiphenyl (2,2 ' -dimethyl-4,4'-diaminobiphenyl), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (2,2-bis [4- (4-aminophenoxy) phenyl] propane), 1, 3-bis (4-aminophenoxy) benzene (1,3-bis (4-aminophenoxy) benzene) and 4,4'-di Diamino benzamide not fluoride (4,4'-diaminobenzanilide), and the like, but not particularly limited to this. Further, these may be used alone or in combination of two or more.

As the aromatic dianhydride-based monomer, 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, BPDA), 2, 2-bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (2,2-bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 6FDA), benzophenone tetracarboxylic dihydride ( benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, oxydiphthalic anhydride, cyclobutane tetracarboxylic dihydride Cyclobutane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) sulfone diane Id fluoride and the like, but (bis (3,4-dicarboxyphenyl) sulfone dianhydride), is not particularly limited. Further, these may be used alone or in combination of two or more.

The polyamic acid is preferably a unit of 3,3 ', 4,4'-diphenyltetracarboxylic acid dianhydride (BPDA) and 2,2'-bis (trifluoromethyl) benzidine (TFDB) It may be a polyamic acid comprising a structure, or 3,3 ', 4,4'-diphenyltetracarboxylic acid dianhydride (BPDA), 2,2'-bis (trifluoromethyl) benzidine (TFDB ) May include a unit structure of terephthaloyl chloride. In this case, mechanical properties may be further improved when used in combination with the azide-based crosslinking agent of the present invention.

The polyamic acid is a composition comprising the aromatic diamine-based monomer and the aromatic dianhydride-based monomer in a molar ratio of 1: 0.5 to 1: 1.5, preferably 1: 0.5 to 1: 1, or 1: 1. It may be polymerized from. When polymerized in the molar ratio, it may be advantageous to secure a lower yellow index (Y.I.), high visible light transmittance, and improved mechanical strength.

In the polyimide precursor composition according to one embodiment of the present invention, the polyamic acid may be in the form of a precursor for preparing a polyamideimide copolymer in which an amide unit structure is introduced into polyimide.

In this case, the aromatic diamine-based monomer and the aromatic dianhydride-based monomer may be obtained through polymerization by applying a dicarbonyl compound for introduction of an amide bond and polymerization.

As the dicarbonyl compound, terephthaloyl chloride, isophthaloyl chloride, biphenyldicarbonyl chloride, terephthalic acid, pyridine-2,5- Dicarbonyl-2,5-dicarbonyl chloride, pyridine-2,5-dicarboxylic acid, pyrimidine-2,5-dicarbonyl chloride (pyrimidine-2,5 -dicarbonyl chloride), pyrimidine-2,5-dicarboxylic acid, 4,4'-biphenyldicarbonyl chloride, and 4,4 '-Biphenyldicarboxylic acid (4,4'-biphenyldicarboxylic acid) and the like.

On the other hand, the polyimide precursor composition according to an embodiment of the present invention, a heat crosslinking agent, curing accelerator, phosphorus flame retardant, antifoaming agent, leveling agent, anti-gel agent or a mixture thereof further within a range that does not affect the desired effect It may further include. As such an additive, if it is known that it can be used in the polyimide resin precursor composition, it can be used without any other limitation, and can be used in an appropriate amount in consideration of the properties of the polyimide resin precursor composition or a film obtained therefrom.

The viscosity of the polyimide precursor composition according to one embodiment of the present invention may be 1,000 to 200,000 cps at 25 ° C, and preferably 5,000 to 100,000 cps. The composition of the present invention, by satisfying the viscosity range at room temperature, it is possible to produce a film having excellent workability, lower yellow index (Y.I.), high visible light transmittance, and improved mechanical properties.

<Method for producing polyimide film>

The present invention relates to a method for producing a polyimide film using the polyimide precursor composition, forming a coating layer by applying the above-described polyimide precursor composition of the present invention to a substrate, and the coating layer is 200 to 300 ° C. And heating.

The method of manufacturing a polyimide film according to an embodiment of the present invention, by heating the coating layer to 200 to 300 ° C., crosslinking between polyimide copolymers by azide compounds represented by the following Chemical Formulas 1 to 4 contained in the coating layer Through the reaction, the mechanical strength of the film can be improved while maintaining a lower yellow index (YI) and high visible light transmittance.

When the temperature of the heating step is less than 200 ° C, imidization of polyamic acid and crosslinking of an azide and a crosslinking agent are not sufficiently achieved, and if it is more than 300 ° C, a problem that the yellow index (YI) of the imide increases may occur. have. The temperature of the heating step may preferably be 230 to 280 ° C, and it is advantageous to realize the above-described effect within the temperature range.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

.

.

In the method for producing a polyimide film according to an embodiment of the present invention, before the heating step, the step of imidizing the polyamic acid in the precursor composition may be further included, wherein the imidization step is chemical imidization or thermal imide. It can be carried out in a furnace.

In addition, in the method of manufacturing a polyimide film according to an embodiment of the present invention, thermal imidization of polyamic acid may be performed together in the heating step, and in this case, thermal imidization of polyamic acid is performed through the heating. And, the prepared polyimide copolymer is crosslinked through an azide-based crosslinking agent. Here, chemical imidization may be performed simultaneously with thermal imidation of the polyamic acid.

Although the execution time of the heating step is not particularly limited, for example, it may be performed for 1 minute to 60 minutes, preferably 5 minutes to 50 minutes, and when performed for the time, sufficient azide crosslinking agent A crosslinking reaction can be carried out, and a problem such as a rise in yellow index (YI) does not occur due to a curing reaction more than necessary, which is preferable.

In the method for producing a polyimide film according to one embodiment of the present invention, the polyamic acid contained in the polyimide precursor composition may be formed by polymerizing an aromatic diamine-based monomer and an aromatic dianhydride-based monomer, and specific components of the monomer And the content may be the same component and content used in the polyimide precursor composition of the present invention described above.

The polymerization conditions for forming the polyamic acid are not particularly limited, but may be prepared using, for example, a low temperature solution polymerization method, an interfacial polymerization method, a melt polymerization method, or a solid phase polymerization method, but are not limited thereto.

The solvent used in the polymerization of the polyamic acid is N, N-dimethylformamide, dimethylacetamide, dimethylsulfoxide, acetone, N-methyl-2-pyrrolidone, tetrahydrofuran, chloroform, gamma-butyrolactone The like may be used, but is not particularly limited.

After polymerization of the aromatic diamine-based monomer and the aromatic dianhydride-based monomer, a step of inducing an imidization reaction may be performed. As described above, the imidization reaction of the polyamic acid and the crosslinking reaction between the polyimide copolymers can be performed simultaneously.

The imidization reaction may be thermally or chemically induced, and compounds such as acetic anhydride and pyridine may be used for the chemical imidation reaction.

In the polyimide precursor composition, the polyamic acid may have a weight average molecular weight (Mw) of 1,000 to 1,000,000 g / mol, and preferably a weight average molecular weight (Mw) of 10,000 to 500,000 g / mol. When the weight average molecular weight (Mw) of the polyamic acid is within the above range, it is preferable because it can be applied to spray coating, spin coating, and slot die coating capable of thin film processing.

In the method for manufacturing a polyamide resin according to an embodiment of the present invention, as a function of a support for forming a coating layer of the substrate, the specific type is not particularly limited, and is appropriately selected for physical properties required for applied products It may be, it is preferable that the coating layer can be easily peeled off, and light transmittance and surface smoothness are good.

Specific examples of the base material, polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene, cellulose triacetate, cellulose diacetate, poly (meth) acrylic acid alkyl ester, poly (meth) acrylic acid ester copolymer, polyvinyl chloride, poly Various plastic films such as vinyl alcohol, polycarbonate, polystyrene, cellophane, polyvinylidene chloride copolymer, polyamide, polyimide, vinyl chloride / vinyl acetate copolymer, polytetrafluoroethylene, and polytrifluoroethylene, or Glass substrates, but are not limited thereto.

<Polyimide film>

In the present invention, by providing the polyimide film made of the above-described polyimide coating composition, by using a specific azide-based compound as a crosslinking agent, while maintaining a lower yellow index (YI), high visible light transmittance mechanical strength of the film To improve.

The polyimide film according to an embodiment of the present invention may have a thickness of 10 to 150 μm, preferably 10 to 100 μm, but is not limited thereto, and is changed to an appropriate range suitable for the use of the applied product Can be. In the present specification, the thickness of the film may mean the thickness of the coating layer from which the release film is removed after drying.

The polyimide film according to one embodiment of the present invention may have a pencil hardness according to ASTM E313 of 4B or more based on a film thickness of 100 ± 10 μm, preferably 2B or more, more preferably F or more.

The polyimide film according to an embodiment of the present invention may have a transmittance at 550 nm of 85% or more when measuring transmittance with a UV spectrometer based on a film thickness of 100 ± 10 μm, preferably 88% to 99%. have.

The polyimide film according to an embodiment of the present invention has a lower yellow index (YI) and a high mechanical strength of the film while maintaining high visible light transmittance, It can be easily applied to flexible, foldable device cover films, and the like.

Hereinafter, the operation and effects of the invention will be described in more detail through specific examples of the invention. However, this is provided as an example of the invention, and the scope of the invention is not limited in any way.

Example  And Comparative example

Manufacturing example  1-Preparation of polyimide precursor composition

(BASED VANISH: 6FDA - TFDB  Occation)

At a molar ratio of 2,2-bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) 0.995 mol, 2,2'-bis (trifluoromethyl) benzidine (TFDB) 1.0 mol, A polyamic acid solution was prepared by dissolving in a dimethylacetamide solvent at a solid content of 15.0% by weight and reacting for 15 to 30 to 12 hours under a nitrogen stream. The viscosity of the polyamic acid measured at 25 ° C prepared above was 86,432 cps.

The polyimide precursor composition was prepared by adding 0.05 parts by weight of an azide-based crosslinking agent represented by the following Chemical Formula 1 with respect to 100 parts by weight of the prepared polyamic acid. The viscosity of the composition measured at 25 ° C was 88,748 cps.

[Formula 1]

.

.

Manufacturing example  2-Preparation of polyimide precursor composition

(BASED VANISH: BPDA - TFDB  Occation)

3,3 ', 4,4'-diphenyltetracarboxylic acid dianhydride (BPDA) 0.995 mol, 2,2'-bis (trifluoromethyl) benzidine (TFDB) at a molar ratio of 1.0 mol, dimethylacet A polyamic acid solution was prepared by dissolving in an amide solvent at a solid content of 15.0% by weight and reacting for 15 to 30 to 12 hours under a nitrogen stream. The viscosity measured at 25 of the polyamic acid prepared above is 65,000 cps.

With respect to 100 parts by weight of the polyamic acid prepared above, 0.05 parts by weight of the azide-based crosslinking agent used in Example 1 was added to prepare a polyimide precursor composition. The viscosity of the composition measured at 25 ° C was 65,500 cps.

Manufacturing example  3-Preparation of polyimide precursor composition

(BASED VANISH: TPCI73  Occation)

3,3 ', 4,4'-diphenyltetracarboxylic acid dianhydride (BPDA) 0.297mol, 2,2'-bis (trifluoromethyl) benzidine (TFDB) 1.0mol terephthaloyl chloride (terephthaloyl chloride) dissolved in a dimethylacetamide solvent at a molar ratio of 0.693 mol to 15.0% by weight, and reacted for 15 to 30 to 12 hours under a nitrogen stream to prepare a polyamic acid solution.

Dimethylacetamide was added to the prepared polyamic acid-containing varnish to dilute the solids content to 5% by weight or less, and then precipitated the solids with 10 L of methanol.

The precipitated solid was filtered and then dried in a vacuum oven at 100 ° C. for 6 hours or more to obtain a polyamide amic acid copolymer in the form of a solid (weight average molecular weight 110,000 g / mol). The polyamide amic acid copolymer was dissolved in dimethylacetamide to obtain a polyamideimide-containing varnish having a solid content of 15.0% by weight.

With respect to 100 parts by weight of the polyamide imide prepared above, 0.05 parts by weight of the azide-based crosslinking agent used in Example 1 was added to prepare a polyamide imide precursor composition. The viscosity of the composition measured at 25 ° C was 112,000 cps.

Manufacturing example  4-Preparation of polyimide precursor composition

(BASED VANISH: 6FDA - TFDB  Occation)

A polyimide precursor composition was prepared in the same manner as in Example 1, except that the crosslinking agent of Chemical Formula 5 was used instead of the crosslinking agent used in Preparation Example 1. The viscosity of the composition measured at 25 ° C was 490,000 cps.

[Formula 6]

Example  And Comparative example  -Preparation of polyimide film

The polyimide precursor compositions of Preparation Examples 1 to 5 having different azide-based crosslinking agent contents were dried on a polyimide film (UPILEX-75, UBE, JAPAN) having a thickness of 75 µm, and the thickness of the coating layer was 49 ± 1 after drying of the coating layer. It was applied to be µm and dried at 80 ° C. for 10 minutes to form a coating layer.

Then, the coating layer was fixed to the flame of the vacuum oven, cured at 250 for 30 minutes while flowing nitrogen, and then the cured film was peeled to obtain a polyimide film.

Experiment method

1. Confirmation of the curing reaction of the polyimide precursor composition

In Preparation Example 1, to confirm the crosslinking reaction of the azide crosslinking agent, FR-IR graphs before and after curing of the precursor composition according to an embodiment of the present invention were measured, and the results are shown in FIG. 1.

Referring to FIG. 1, it was confirmed that the intrinsic peak of the azide in the 2150 nm region before curing disappeared after curing.

2. Experiment of physical properties of polyimide film

The physical properties of the prepared polyimide film were measured by the following method.

(1) Yellowness Index (YI) Measurement Method: UV-2600 UV-Vis Spectrometer (SHIMADZU) was used to measure the initial yellowness index (YI ₀ ) of the film according to the measurement method of ASTM D1925, and the values are shown in Table 1 below. It is shown in.

(2) Transmittance measurement method: UV-2600 UV-Vis Spectrometer (SHIMADZU) was used to measure the total light transmittance (%) of the film, and the transmittance values for visible light at a wavelength of 550 nm are shown in Table 1 below.

(3) Method of measuring mechanical properties: Modulus (GPa) and Tensile (MPa) were measured through ASTM D 882 method using equipment of Universal Testing Machine (Zwick / RoellZ0.5), and the results are shown in Table 1 below. It is shown in.

(3) Elongation measuring method: Tensile elongation according to ASTM D 882 was measured using a Universal Testing Machine (Zwick / Roell Z0.5). After preparing a sample of thickness (㎛) * length (60mm) * width (6mm), elongation (%) was measured at an elongation compared to the initial length at the fracture point of the sample by applying a force in the tensile direction. It is shown in Table 1 below.

(4) Pencil Hardness Measurement Method: The pencil hardness of the film was measured according to the measurement method of ASTM D3363 using a Pencil Hardness Tester. Specifically, after fixing the pencils of various hardness to the tester and scratching the film, the degree of scratches on the film was observed with the naked eye or a microscope, and when more than 70% of the total number of scratches was not scratched, the hardness of the pencil The corresponding value was evaluated for the pencil path of the film, and the results are shown in Table 1 below.

(5) Method for measuring break strength: The break strength of the film was evaluated using a MIT type folding endurance tester. Specifically, a specimen (1 cm * 7 cm) of the film was loaded into a fracture resistance tester and bent at a speed of 175 rpm from the left and right sides of the specimen at an angle of 135 °, a radius of curvature of 0.8 mm, and a load of 250 g until fracture. The reciprocating bending cycle was measured, and the results are shown in Table 1 below.

division Precursor composition Y.I. Modulus
(GPa) Tensile
(MPa) Elogation
(%) Pencil hardness Transmittance
(%) MIT Suzy Crosslinker
(Parts by weight) * Comparative Example 1 6FDA-TFDB of Preparation Example 1 0 2.32 3.42 137.5 8.4 Less than 6B 91.19 95301 Example 1 1.0 2.47 3.48 134.7 8.4 2B 91.24 105882 Example 2 BPDA-TFDB of Preparation Example 2 0.5 5.90 4.93 217 22 F 87.79 29873 Example 3 1.0 6.54 5.04 220 23 H 87.56 29910 Example 4 TPCI73 of Preparation Example 3 0.5 4.04 5.22 198 17 4H 88.67 10690 Comparative Example 2 6FDA-TFDB of Preparation Example 4 0.5 7.56 3.45 100.2 4.5 5B 90.16 68500 * The content of crosslinking agent is based on 100 parts by weight of polyamic acid

When the polyimide film was prepared using an azide-based crosslinking agent as in the embodiment of the present invention, it was confirmed that colorless transparent and excellent mechanical properties were realized.

On the other hand, in Comparative Example 1 without using the azide-based crosslinking agent of the present invention, it was confirmed that the pencil hardness of the film of Example 1 using the same polyimide copolymer was significantly reduced.

In addition, in the case of Comparative Example 2 using a different type of crosslinking agent instead of the azide-based crosslinking agent of the present invention, the viscosity of the composition measured at room temperature after preparation was significantly increased compared to the example, and thus the crosslinking reaction was not uniformly performed, resulting in a film It was confirmed that the mechanical properties of the product were lowered and the yellow index was also very high.

Claims (11)

A polyamic acid comprising a unit structure derived from an aromatic diamine-based monomer and a unit structure derived from an aromatic dianhydride-based monomer; And an azide-based crosslinking agent comprising at least one of compounds represented by the following Chemical Formulas 1 to 4;
The azide-based crosslinking agent is contained in 0.01 to 5 parts by weight based on 100 parts by weight of polyamic acid, polyimide precursor composition:
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

.
delete According to claim 1,
The aromatic diamine-based monomer is 2,2'-bis (trifluoromethyl) -4,4'-biphenyldiamine (2,2'-bis (trifluoromethyl) -4,4'-biphenyldiamine), 4, 4'-diaminodiphenyl sulfone, 4,4 '-(9-fluorenylidene) dianiline, 4,4'-(9-fluorenylidene) dianiline, bis (4 -(4-aminophenoxy) phenyl) bis (4- (4-aminophenoxy) phenyl) sulfone), 2,2 ', 5,5'-tetrachlorobenzidine (2,2', 5,5'- tetrachlorobenzidine), 2,7-diaminofluorene, 4,4-diaminooctafluorobiphenyl, m-phenylenediamine, p -Phenylenediamine, 4,4'-oxydianiline, 2,2'-dimethyl-4,4'-diaminobiphenyl (2,2'- dimethyl-4,4'-diaminobiphenyl), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (2,2-bis [4- (4-aminophenoxy) phenyl] propane), 1,3 -Bis (4-aminophenoxy) benzene (1,3-bis (4-aminophenoxy) benzene) and 4,4'-dia One member selected from the group consisting of fluoride furnace benzamide (4,4'-diaminobenzanilide) is not more than, the polyimide precursor composition.
According to claim 1,
The aromatic dianhydride-based monomer, 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, BPDA), 2,2 -Bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (2,2-bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 6FDA), benzophenone tetracarboxylic dianhydride (benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, oxydiphthalic anhydride, cyclobutane tetracarboxylic dihydride (cyclobutane tetracarboxylic dianhydride), cyclopentane tetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) sulfone diane Deurayideu at least one member, the polyimide precursor composition is selected from the group consisting of (bis (3,4-dicarboxyphenyl) sulfone dianhydride).
According to claim 1,
The viscosity of the composition is 1,000 to 200,000cps, polyimide precursor composition.
Forming a coating layer by applying the polyimide precursor composition according to claim 1 to a substrate,
Heating the coating layer to 200 to 300 ℃; including, polyimide film production method.
The method of claim 6,
The heating step is performed for 1 to 60 minutes, the method for producing a polyimide film.
A polyimide film formed of the polyimide precursor composition according to claim 1.
The polyimide film of claim 8 having a thickness of 10 to 150 μm.
The method of claim 8,
A polyimide film having a pencil hardness of 4B or more according to ASTM E313 based on a film thickness of 100 ± 10 μm.
The method of claim 8,
A polyimide film having a transmittance at 550 nm of 85% or more when measuring transmittance with a UV spectrometer based on a film thickness of 100 ± 10 μm.

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