TWI723360B - Polyimide precursor composition comprising crosslinkable dianhydride compound and antioxidant, polyimide film prepared therefrom and preparation method thereof, and electronic device comprising the same - Google Patents

Abstract

The invention provides a polyimide precursor composition, a polyimide film prepared using the same, a preparation method thereof, and an electronic device including the polyimide film. The polyimide precursor composition includes a polyimide solution prepared by polymerizing more than one dianhydride monomer and more than one diamine monomer in an organic solvent, and a decomposition temperature of 5 wt% is For antioxidants above 380°C, the above-mentioned dianhydride monomer includes a cross-linkable dianhydride compound, and the above-mentioned cross-linkable dianhydride compound includes at least one triple bond in the molecular structure.

Description

Polyimide precursor composition comprising crosslinkable dianhydride compounds and antioxidants, polyimide film prepared from the above polyimide precursor composition, preparation method thereof, and polyimide film Electronic device

The present invention relates to a polyimide precursor composition comprising a crosslinkable dianhydride compound and an antioxidant, and a polyimide film prepared from the polyimide precursor composition.

Polyimide (PI) is a thermally stable polymer material based on a strong aromatic main chain. Based on the chemical stability of the imide ring, it has excellent strength, chemical resistance, and weather resistance. , Mechanical properties such as heat resistance.

Moreover, polyimide is favored as a highly functional polymer material that can be widely used in electronics, communications, optics and other industrial fields due to its excellent electrical properties such as insulation properties and low dielectric constant.

Recently, various electronic devices have become thinner, lighter, and smaller. Therefore, many researches are directed toward the use of lightweight and flexible thin polyimide films as insulating materials that can replace circuit boards or glass substrates for displays. The direction of the display substrate is carried out.

In particular, polyimide films used for circuit substrates or display substrates prepared at high process temperatures need to ensure a higher level of dimensional stability, heat resistance, and mechanical properties.

As one of the methods for ensuring such physical properties, a method of increasing the molecular weight of polyimide can be cited.

The reason is that the more iminium groups in the molecule, the more heat resistance and mechanical properties of the polyimide film can be improved. The longer the polymer chain, the more the ratio of iminium groups increases. Therefore, the preparation of high molecular weight Polyimide helps ensure physical properties.

In order to prepare high-molecular-weight polyimide, it is necessary to prepare polyamic acid as its precursor to high molecular weight. However, the higher the molecular weight of the polyamide, the more the viscosity of the polyamide solution will increase.

However, when the viscosity of the polyamic acid solution is too high, the fluidity decreases and the process handling properties become very low.

On the other hand, polyimide resins generally cause chemical changes, that is, oxidation reactions, due to light, heat, pressure, shear force, etc. in the presence of oxygen. Such an oxidation reaction changes the physical properties of the polyimide resin due to molecular chain scission, cross-linking, etc., thereby causing problems that the heat resistance and mechanical properties of the prepared polyimide film are reduced.

In order to solve this problem, a method of adding a small amount of additives such as antioxidants is being used. The antioxidants, for example, have the function of removing oxygen atoms from the oxidized polyimide resin and stabilizing the polyimide resin, and are typically used Phosphate compounds and sulfur compounds.

However, commonly used antioxidants have the property of decomposing at high temperatures, especially when preparing polyimide resins, high-temperature heat treatment is usually performed to achieve imidization. Therefore, the antioxidants decompose at this time and have anti-oxidation effects. Reduce or, depending on the situation, the problem of completely unable to exert this effect.

As mentioned above, it is very difficult to improve the properties required by the polyimide precursor composition and the polyimide resin prepared therefrom. In particular, when one property is improved, the other property is lowered. Therefore, in the related art In the field, researches to satisfy multiple characteristics are constantly being carried out.

Therefore, the fact is that there is an urgent need for a polyimide precursor composition that is excellent in process handling properties and satisfies the heat resistance and mechanical properties of the polyimide film to be prepared.

[The problem to be solved by the invention] The object of the present invention is to provide a polyimide film that maintains a low viscosity of the polyamide acid solution and has high process handling properties, and at the same time satisfies the heat resistance and mechanical properties of the polyimide film prepared from the polyamide acid solution. An imine precursor composition and a polyimide film prepared from the polyimine precursor composition.

According to an aspect of the present invention, a polyamide acid solution prepared by polymerizing more than one dianhydride monomer and more than one diamine monomer in an organic solvent and an antioxidant are included, and the dianhydride monomer includes crosslinking The polyimide precursor composition of a sexual dianhydride compound reveals the necessary factors for realizing a polyimide film that satisfies the above-mentioned characteristics.

Therefore, the essential objective of the present invention is to provide specific examples of the aforementioned polyimide precursor composition.

[Means to solve the problem] The present invention provides a polyimide precursor composition, which comprises: a polyimide acid solution prepared by polymerizing more than one dianhydride monomer and more than one diamine monomer in an organic solvent; and Antioxidant, the decomposition temperature of 5 wt% is above 380℃; and The above-mentioned dianhydride monomer includes a cross-linkable dianhydride compound, and the above-mentioned cross-linkable dianhydride compound includes at least one triple bond in the molecular structure.

The present invention also found the following situation: in the case of using the polyimide precursor composition, the solid content is higher, and the process handleability can be improved due to the relatively low viscosity, and the polyimide precursor composition The polyimide film prepared by the composite composition exhibits excellent heat resistance and mechanical properties.

Therefore, in this specification, specific content for realizing the above-mentioned polyimide film will be described.

Prior to this, the terms or words used in this specification and the scope of patent applications for inventions should not be limitedly interpreted as ordinary meanings or dictionary meanings. In order for the inventor to explain his own invention in the best way, he should only be based on The principles of the concepts of terms can be appropriately defined and interpreted as meanings and concepts that conform to the technical idea of the present invention.

Therefore, the configuration of the embodiment described in this specification is only the best embodiment of the present invention, and does not represent all the technical ideas of the present invention. Therefore, it should be understood that there may be alternatives from the perspective of this application. Various equivalents and modifications of the above-mentioned embodiment.

In this specification, the expression in the singular includes the expression in the plural as long as other meanings are not clearly expressed in the text. In this specification, it should be understood that terms such as "include", "have" or "have" indicate the existence of implemented features, numbers, steps, constituent elements or combinations thereof, and do not preclude one or more other features, numbers, The existence or additional possibilities of steps, constituent elements, or combinations thereof.

In this specification, "dianhydride" refers to those including its precursors or derivatives, which may not be dianhydrides technically, but even so, it also reacts with diamine to form polyamide acid. The above-mentioned polyamide can be converted into polyimide again.

In this specification, "diamine" refers to those including its precursors or derivatives. They may not be diamines technically, but even so, they also react with dianhydrides to form polyamide acid. Amino acids can be converted into polyimides again.

In this specification, when an amount, concentration, other value or parameter is listed as a range, a preferred range, or a preferred upper limit and a preferred lower limit, it should be understood that it has nothing to do with whether the range is otherwise disclosed. Specifically, all ranges formed by any pair of any upper range limit value or preferred value and any lower range limit value or preferred value are disclosed.

When referring to the range of a numerical value in this specification, unless otherwise stated, the range includes the end point and all integers and fractions within the range.

The scope of the present invention is not limited to the specific values mentioned when defining the scope.

First 1 Embodiment: Polyimide precursor composition

The polyimide precursor composition of the present invention is characterized by comprising: a polyimide acid solution prepared by polymerizing more than one dianhydride monomer and more than one diamine monomer in an organic solvent; and Antioxidant, the decomposition temperature of 5 wt% is above 380℃; and The above-mentioned dianhydride monomer includes a cross-linkable dianhydride compound, and the above-mentioned cross-linkable dianhydride compound includes at least one triple bond in the molecular structure.

The solid content may be 10% to 20% by weight based on the total weight of the polyimide precursor composition.

When the solid content of the polyimide precursor composition is greater than the above range, the viscosity of the polyimide precursor composition will inevitably increase, so it is not good. On the contrary, in the polyimide precursor composition When the solid content of the material is less than the above range, a large amount of solvent needs to be removed during the hardening process, which will cause the problem of increased production cost and process time.

In addition, the viscosity of the polyimide precursor composition at 23° C. is in the range of 1,000 cP to 20,000 cP, in detail, it may be in the range of 2,000 cP to 10,000 cP, and more specifically, 3,000 cP to 6,000 cP. range.

The polyimide precursor composition with this viscosity has the advantage of being easy to handle in the manufacturing process in terms of fluidity, and will also be beneficial to film formation. In detail, when the viscosity of the polyimide precursor composition is greater than the above range, when the polyimide precursor composition is moved by the tube during the preparation process of the polyimide film, The friction with the tube requires higher pressure, so the process cost increases and the handling ability decreases. In addition, the higher the viscosity, the more time and expense will be spent in the mixing process.

On the contrary, when the viscosity of the polyimide precursor composition is less than the above range, a large amount of solvent needs to be removed during the hardening process, which causes problems of increased production cost and process time.

On the other hand, based on 100 mol% of the above-mentioned diamine monomer, the content of the above-mentioned dianhydride monomer may be 88 mol% to 99.5 mol%, and the content of the above-mentioned crosslinkable dianhydride compound is 0.5 mol%. Ear% to 12 mol%.

In more detail, based on 100 mol% of the diamine monomer, the content of the dianhydride monomer may be 90 mol% to 99 mol%, and the content of the crosslinkable dianhydride compound is 1 Mole% to 10 Mole%.

When a crosslinkable dianhydride compound is added in a manner larger than the above range to prepare a polyimide precursor composition, the flexibility of the polyimide film decreases, and it is difficult to form a film. In this case, the heat resistance and mechanical properties of the polyimide film prepared therefrom will decrease, so it is not good.

（1）In a specific example, the crosslinkable dianhydride compound may be a compound represented by the following chemical formula 1.

(1)

Here, L may be a C2-C6 alkynyl group, and R ₁ and R ₂ are each independently selected from the group consisting of C1-C3 alkyl, aryl, carboxylic acid, hydroxyl, fluoroalkyl, and sulfonic acid groups. When R ₁ and R ₂ are plural, they may be the same or different from each other, and n and m are each independently an integer from 0 to 3.

In the above chemical formula 1, when the substituent of the benzene ring is not specifically specified, the above substituent refers to hydrogen.

（1-1）In a more specific example, the cross-linkable dianhydride compound may be Ethynylbisphthalicanhydride (EBPA) represented by the following chemical formula 1-1.

(1-1)

Here, the triple bond included in the molecular structure of the above-mentioned cross-linkable dianhydride compound serves as three electron pairs participating in the bonding, including one σ (sigma) bond and two π (pi) bonds. The above-mentioned π bond exhibits unsaturation, and therefore has the property of easily causing an addition reaction or a polymerization reaction and also being easily broken.

The polyimide precursor composition of the present invention includes a cross-linkable dianhydride compound containing the above-mentioned triple bond, and the polyimide precursor composition produced by the polymerization reaction of a dianhydride monomer and a diamine monomer can be Two or more polyamide acid chains having triple bonds derived from crosslinkable dianhydride compounds are included.

The polyimide precursor composition including the polyimide chain of the above-mentioned structure does not form a crosslinked bond between triple bonds in a solution state, so it can exhibit a difference from a crosslinkable dianhydride compound that is not derived from it. The viscosity of the usual polyimide precursor composition is similar.

However, during the heat treatment to achieve imidization, more than one cross-linking bond can be formed by the free radical reaction between the triple bonds included in different polyamide acid chains, so that it can be converted into polyamide. After the imide, the bonding force between the polymers is increased due to the cross-linking bond, which can significantly improve the mechanical properties and heat resistance compared with the usual polyimide film.

In a specific example, the above-mentioned polyimide precursor composition may have the following structure: it may include a first polyimide chain having triple bonds derived from a crosslinkable dianhydride compound, and having a structure derived from a crosslinkable dianhydride compound. In addition to the second polyamide chain of the triple bond of the compound, a plurality of polyamide chains having triple bonds are included.

The above-mentioned polyimide precursor composition is in the following form: when the heat treatment for realizing imidization is performed, the first triple bond included in the first polyimide chain and the second polyimide chain are respectively The included second triple bond forms free radicals from the broken π bond, and free gene radicals with higher reactivity react to cross-link and bond with each other; the first polyamide chain and the second polyamide chain can be cross-linked and bonded. Chain cross-linking.

As a result, the first polyimide chain and the second polyimide chain can form crosslink bonds between the polyimide chains through the reaction as described above during the imidization process, except for the first In addition to the polyamide chain and the second polyamide chain, each of the polyamide acid chains includes a plurality of triple bonds, so the above-mentioned crosslinking bonds can be formed between the polyamide acid chains. .

This kind of cross-linking bond can significantly improve the mechanical properties and heat resistance compared with a polyimide film that does not include a cross-linking bond.

According to the present invention, in order to improve the heat resistance and mechanical properties of the polyimide film, a crosslinkable dianhydride compound is used to prepare a polyimide precursor composition instead of preparing a polyimide precursor composition with a very high molecular weight. In the case of high-viscosity polyimide precursor composition, even if a relatively low-viscosity polyimide precursor composition is used, it can still perform at a level similar to that of a polyimide film prepared from a polyimide precursor composition with high viscosity. Heat resistance and mechanical properties.

In addition, when a low-viscosity polyimide precursor composition is used, it has the effect of further improving the processability.

On the other hand, the decomposition temperature of 5 wt% of the antioxidant is 380°C or higher, and in detail, the decomposition temperature of 5 wt% may be 400°C or higher.

（2）Specifically, the above-mentioned antioxidant may include a compound represented by Chemical Formula 2 below.

(2)

In the above chemical formula 2, R _1a to R _6a are each independently selected from the group consisting of C1-C3 alkyl, aryl, carboxyl, hydroxyl, fluoroalkyl and sulfonic acid groups, and R _1a to R _6a are more In the case of both, they may be the same or different from each other, n1 is an integer from 1 to 4, and m1 to m6 are independently an integer from 0 to 3, respectively.

In the above chemical formula 2, when the substituent of the benzene ring is not specifically specified, the above substituent refers to hydrogen.

（2-1）In a specific example, in the above chemical formula 2, n1 may be 1, and m1 to m6 are 0. More specifically, the above antioxidant may be a compound of the following chemical formula 2-1.

(2-1)

This antioxidant has low volatility and excellent thermal stability, so it will not decompose or volatilize during the preparation process of the polyimide film, and can play a role in preventing the amide group or polyimide group in the polyimide precursor composition. The effect of oxidation of the imine group of the imine film.

On the contrary, 5 wt% of antioxidants with a decomposition temperature of 380°C or lower are decomposed due to high temperatures during the preparation process of the polyimide film, and thus cannot exert the effects achieved by the addition of the antioxidants as described above.

With respect to 100 parts by weight of the solid content of the polyimide precursor composition, 0.1 to 2.5 parts by weight of the above-mentioned antioxidant may be included. More specifically, with respect to 100 parts by weight of the solid content of the polyimide precursor composition. Parts by weight, the above-mentioned antioxidant is included in the range of 0.1 parts by weight to 2.0 parts by weight.

When the content of this antioxidant is greater than the above range, the heat resistance will decrease instead, and deposition or blooming will occur in the polyimide film, which will reduce the mechanical properties and the appearance of the film will be poor. Suboptimal.

Conversely, when the content of the antioxidant is less than the above range, the antioxidant effect cannot be fully exhibited, and therefore it is not preferable.

On the other hand, as described above, the polyimide precursor composition can be produced by the polymerization reaction of one or more dianhydride monomers and one or more diamine monomers.

The dianhydride monomer that can be used to prepare the polyamide acid of the present invention may be an aromatic tetracarboxylic dianhydride.

The above-mentioned aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (or s-BPDA), 2,3,3 ',4'-Biphenyltetracarboxylic dianhydride (or α-BPDA), oxydiphthalic dianhydride (or ODPA), diphenyl sulfide-3,4,3',4'-tetracarboxylic acid Dianhydride (or DSDA), bis(3,4-dicarboxyphenyl) sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3 -Hexafluoropropane dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (or BTDA) , Bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylene bis(trimellitic acid monoester anhydride), P-biphenyl bis (trimellitic acid monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4 '-Tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1,4-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1, 4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3, 6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride Wait. These etc. can be used individually or in combination of 2 or more types as desired.

These can be used singly or in combination of two or more as desired. However, in the present invention, the dianhydride monomers that can be particularly utilized include those selected from pyromellitic dianhydride (PMDA), 3,3' ,4,4'-Biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'-Biphenyltetracarboxylic dianhydride (α-BPDA) are composed of more than one species.

The diamine monomers that can be used to prepare the polyamide acid of the present invention can be classified and listed as aromatic diamines as follows.

1) Such as 1,4-diaminobenzene (or p-phenylenediamine, p-PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (or DABA) and other diamines with relatively strong structure as a diamine with a benzene nucleus in the structure; 2) Such as 4,4'-diaminodiphenyl ether (or oxydiphenylamine, ODA), 3,4'-diaminodiphenyl ether and other diaminodiphenyl ethers, 4,4'-diamine Diphenylmethane (methylene diamine), 3,3'-dimethyl-4,4'-diamino biphenyl, 2,2'-dimethyl-4,4'-diamino biphenyl Benzene, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3 '-Dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminobenzene Base) thioether, 4,4'-diaminobenzidine, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine), 2,2' -Dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide Chrysene, 3,4'-diaminodiphenyl chrysene, 4,4'-diaminodiphenyl chrysene, 3,3'-diamino benzophenone, 4,4'-diamino benzophenone Benzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3, 3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl) Propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1, 1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfene, 3,4'-diaminodiphenyl sulfene, 4,4'-diaminodiphenyl Diamines with two benzene nuclei in structure, such as sulfonium; 3) Such as 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1, 4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (or TPE-Q) , 1,4-bis(4-aminophenoxy)benzene (or TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3' -Diamino-4-(4-phenyl)phenoxybenzophenone, 3,3'-diamino-4,4'-bis(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4-aminophenylsulfide)benzene , 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1 ,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-bis[2 -(4-Aminophenyl)isopropyl]benzene and other diamines with 3 benzene nuclei in the structure; 4) Such as 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-amino) Phenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4- Aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3 -(3-Aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]ketone , Bis[4-(4-aminophenoxy)phenyl]ketone, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy) )Phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-( 3-aminophenoxy) phenyl] ash, bis[3-(4-aminophenoxy)phenyl] ash, bis[4-(3-aminophenoxy)phenyl] ash, double [4-(4-aminophenoxy)phenyl] chrysene, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl ]Methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3- Aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy) Phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3- Hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-( 4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane and other diamines having 4 benzene nuclei in the structure.

These can be used singly or in combination of two or more as desired. However, in the present invention, the diamine monomer that can be particularly used can be selected from p-phenylenediamine (p-PDA), 1,3- Diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, and 3,5-diaminobenzoic acid (DABA) are composed of more than one species.

When the input amount of the above dianhydride monomer is greater or less than the above range, the polymerization is terminated before reaching the desired molecular weight, or low molecular weight oligomers are mostly formed, so it is difficult to achieve a polyimide film formation. Polyimide precursor composition.

The polyimide precursor composition can essentially be charged with equal moles of the diamine monomer and dianhydride monomer. Specifically, based on 100 mole% of the diamine monomer, the dianhydride monomer The input amount of the body can be 99 mol% to 101 mol%. More specifically, based on 100 mol% of the above diamine monomer, the input amount of the above dianhydride monomer can be 99 mol% to 101 mol%. 99.9 mol%.

When the input amount of the above dianhydride monomer is greater or less than the above range, the polymerization is terminated before reaching the desired molecular weight, or low molecular weight oligomers are mostly formed, so it is difficult to achieve a polyimide film formation. Polyimide precursor composition.

First 2 Implementation mode: preparation method of polyimide film and polyimide film

The preparation method of the polyimide film of the present invention may include: (A) A process of putting more than one dianhydride monomer and more than one diamine monomer into an organic solvent for polymerization to prepare a polyamide acid solution; (B) The process of preparing a polyimide precursor composition by mixing antioxidants in the above polyamide acid solution; and (C) A process of forming a film of the above polyimide precursor composition onto a support and drying to prepare a gel film, and preparing the polyimide film by imidizing the above gel film; and The above-mentioned dianhydride monomer includes a cross-linkable dianhydride compound, and the above-mentioned cross-linkable dianhydride compound includes at least one triple bond in the molecular structure.

As described above, the polyimide chain included in the polyimide precursor composition includes at least one polyimide chain having triple bonds derived from the crosslinkable dianhydride compound. In the above process (c In ), during the heat treatment for realizing the imidization, more than one cross-linking bond can be formed by free radical reaction between the triple bonds included in different polyamide acid chains.

That is, by the cross-linking between the triple bonds as described above, it is not necessary to excessively increase the molecular weight in the state of the polyimide precursor composition in order to improve the heat resistance and mechanical properties of the prepared polyimide film. To ensure a similar level of heat resistance and mechanical properties to the polyimide film prepared from the polyimide precursor composition with high molecular weight.

In the present invention, the preparation of the polyamide acid solution can be exemplified by the following methods: (1) A method in which the entire amount of the diamine monomer is put into the solvent, and thereafter the dianhydride monomer is added so as to be substantially equal to the diamine monomer to polymerize; (2) A method in which the entire amount of the dianhydride monomer is put into the solvent, and then the diamine monomer is added and polymerized in such a way that it becomes substantially equal to the dianhydride monomer; (3) After putting some of the components in the diamine monomer into the solvent, mix some of the components in the dianhydride monomer at a ratio of about 95 mol% to 105 mol% with respect to the reaction components, and then add The remaining diamine monomer components, and the remaining dianhydride monomer components are continuously added here, so that the diamine monomer and the dianhydride monomer are substantially equal-molar for polymerization; (4) After putting the dianhydride monomer in the solvent, mix a part of the diamine monomer at a ratio of 95 mol% to 105 mol% relative to the reaction components, and then add other dianhydride monomers Components, and continue to add the remaining diamine monomer components to make the diamine monomer and the dianhydride monomer essentially become equal moles for polymerization; (5) A part of the diamine monomer component and a part of the dianhydride monomer component are reacted in a solvent to form the first composition, and a part of the diamine monomer component and a part of the dianhydride monomer Any one of the components is excessively reacted in another solvent to form the second composition, and then the first composition and the second composition are mixed to complete the polymerization. At this time, when the first composition is formed, the second composition is formed. When the amine monomer component is too much, the dianhydride monomer component is excessive in the second composition, and when the dianhydride monomer component is too much in the first composition, the diamine monomer component is excessive in the second composition. The method of mixing the first composition and the second composition, and the overall diamine monomer component and the dianhydride monomer component used for the reaction thereof are substantially equal-molar and polymerized.

However, the above-mentioned polymerization method is not limited to the above-mentioned examples, and of course any known method can be used.

The above-mentioned dianhydride monomers can be appropriately selected from the examples described above. In detail, in addition to crosslinkable dianhydride compounds, they may be selected from pyromellitic dianhydride (PMDA), 3,3', At least one of the groups consisting of 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic dianhydride (α-BPDA).

The above-mentioned diamine monomer can be appropriately selected from the examples described above. In detail, it can be preferably selected from the group consisting of p-phenylenediamine (p-PDA), 1,3-diaminobenzene (MPD), and 2 One or more of the group consisting of ,4-diaminotoluene, 2,6-diaminotoluene and 3,5-diaminobenzoic acid (DABA).

In the preparation method of the present invention, the polyimide film can be prepared by the thermal imidization method, and the chemical imidization method may also be used in parallel.

The above-mentioned thermal imidization method refers to a method of inducing an imidization reaction using a heat source such as hot air or an infrared dryer while excluding a chemical catalyst.

The above-mentioned thermal imidization method may include the above-mentioned process (c). In the above-mentioned process (c), the gel film may be heat-treated at a variable temperature in the range of 100°C to 600°C so as to be present in the gel. The amidation of the amide of the film, in detail, can be heat-treated at 200°C to 500°C, more specifically, 300 to 500°C to remove the amide present in the gel film.化.

However, in the process (c) of forming the above-mentioned gel film, a part of the amide acid (about 0.1 mol% to 10 mol%) can also be imidized. For this reason, in the above process (c) The polyamide composition can be dried at a variable temperature ranging from 50°C to 200°C, and this situation can also be included in the category of the above-mentioned thermal imidization method.

The thermal decomposition temperature of 1% by weight of the polyimide film of the present invention prepared according to the above-mentioned preparation method can be 550°C to 620°C, the coefficient of thermal expansion (CTE) is 2.0 ppm/°C to 8.0 ppm/°C, and glass The transition temperature is above 400℃, the elongation is above 13%, the tensile strength is above 270 MPa, and the thickness is 10 μm to 20 μm.

In more detail, the glass transition temperature of the polyimide film of the present invention may be 417°C or higher.

In the case of a parallel chemical imidization method, a dehydrating agent and an imidizing agent can be used to prepare a polyimide film according to a method known in the industry.

The present invention also provides an electronic device including the above-mentioned polyimide film. The above-mentioned electronic device may be an electronic device including a flexible circuit substrate or a display substrate.

[Effects of the invention] The polyimide precursor composition of the present invention includes a crosslinkable dianhydride compound including at least one triple bond in the molecular structure, so that the heat treatment for achieving imidization can be performed by different The free radicals between the triple bonds included in the polyimide chain react to form more than one cross-linked bond, so the heat resistance and mechanical properties of the polyimide film can be improved.

In addition, the polyimide precursor composition of the present invention has improved heat resistance and mechanical properties during the heat treatment for realizing imidization, so the viscosity of the polyimide precursor composition can be kept low. This can significantly improve the processability.

In addition, the 5% by weight of the antioxidant contained in the polyimide precursor composition with a decomposition temperature of 380°C or higher has low volatility and excellent thermal stability, and therefore does not decompose during the preparation process of the polyimide film Or volatilization can prevent oxidation of the amide group in the polyimide precursor composition or the amide group of the polyimide film, thereby minimizing the change in the physical properties of the polyimide film.

Such a polyimide film has the advantages of meeting the heat resistance and mechanical properties required by the display substrate.

Hereinafter, the function and effect of the invention will be described in more detail through specific embodiments of the invention. However, these embodiments are only examples of the invention, and do not define the scope of rights of the invention.

Hereinafter, the compound names of the abbreviations used in the examples and comparative examples are as follows. -Biphenyltetracarboxylic dianhydride: BPDA -Pyromellitic dianhydride: PMDA -Ethynyl diphthalic anhydride: EBPA -P-phenylenediamine: p-PDA -N-Methylpyrrolidone: NMP

<Example 1>

Inject nitrogen gas into a 500 ml reactor equipped with a stirrer and nitrogen gas injection and discharge pipes, and put in NMP, set the temperature of the reactor to 30°C, and then put in p-PDA as the diamine monomer and the dianhydride monomer It was confirmed that 1 mol of EBPA was added to 100 mol of p-PDA to completely dissolve the BPDA.

The temperature was raised to 40°C in a nitrogen environment for heating, and after stirring was continued for 120 minutes, a polyamic acid solution with a viscosity of 6100 cP at 23°C was prepared.

（2-1）After the temperature of the reactor was set to 50°C, 5 wt% of the compound of the chemical formula 2-1 with a decomposition temperature of about 402°C was added as an antioxidant to the polyamide acid solution, and the reaction was sufficiently stirred until the reaction was completed. Add NMP so that the total solid content becomes approximately 15% by weight and the viscosity becomes approximately 3,700 cP, and the molar ratio of the diamine monomer, dianhydride monomer, and crosslinkable dianhydride compound is 100:99:1. And the polyimide precursor composition which contains 0.5 weight part of antioxidants with respect to 100 weight part of solid components.

(2-1)

The air bubbles in the polyimide precursor composition are removed by high-speed rotation at 1,500 rpm or more. After that, the defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. After that, the gel film was prepared by drying under a nitrogen atmosphere and a temperature of 120°C for 30 minutes. The gel film was heated to 450°C at a rate of 2°C/min, and a heat treatment was performed at 450°C for 60 minutes. The temperature was cooled to 30°C at a rate of °C/min to obtain a polyimide film.

After that, it was dipped in distilled water, and the polyimide film was peeled off from the glass substrate. The thickness of the prepared polyimide film was 15 μm. The thickness of the prepared polyimide film was measured using a film thickness tester (Film thickness tester) of Anritsu Company.

<Example 2 to Example 14 and Comparative Example 1 to Comparative Example 6>

The viscosity of the monomer, additive, and polyimide precursor composition in Example 1 was changed as shown in Table 1 below, respectively, except that the polyimide film was prepared by the same method as in Example 1.

<Comparative Example 7>

（A）The compound of the following chemical formula A with a decomposition temperature of about 377°C of 5 wt% was added instead of the compound of the chemical formula 2-1 in Example 1 as the antioxidant, and it was prepared by the same method as in Example 1, except that Polyimide film.

(A)

<Comparative Example 8>

（B）The compound of the following chemical formula B with a decomposition temperature of about 338°C was added at 5 wt% instead of the compound of the chemical formula 2-1 in Example 1 as the antioxidant, and it was prepared by the same method as in Example 1, except that Polyimide film.

(B)

[Table 1]

<Experimental example 1: Evaluation of physical properties>

The physical properties of the polyimide films prepared in Example 1 to Example 14 and Comparative Example 1 to Comparative Example 8 were measured in the following manner, and the results are shown in Table 2 below.

(1) Coefficient of Thermal Expansion (CTE)

Using TA’s thermomechanical analyzer (thermomechanical analyzer) model Q400, after cutting the polyimide film with a width of 2 mm and a length of 10 mm, a tension of 0.05 N was applied in a nitrogen environment and the temperature was 10℃/min. The rate was raised from room temperature to 500°C, and then cooled again at a rate of 10°C/min to measure the gradient of the interval from 100°C to 350°C.

(2) Thermal decomposition temperature (TD) of 1% by weight

Using TA’s thermogravimetric analyzer model Q50, the polyimide film was heated to 150°C at a rate of 10°C/min in a nitrogen environment, and then kept at isothermal temperature for 30 minutes to remove water. Thereafter, the temperature was raised to 600°C at a rate of 10°C/min, and the temperature at which 1% weight loss occurred was measured.

(3) Glass transition temperature (Tg)

Using TA’s Dynamic Mechanical Analyzer (Dynamic Mechanical Analyzer) model Q800, after cutting the polyimide film with a width of 4 mm and a length of 20 mm, the polyimide film was cut from room temperature to 550°C in a nitrogen environment. The glass transition temperature is measured at a heating rate of 5°C/min. The above-mentioned glass transition temperature is determined as the maximum peak value of tanδ calculated from the ratio of storage modulus and loss modulus.

(4) Elongation

After cutting the polyimide film with a width of 10 mm and a length of 40 mm, the Instron 5564 Universal Testing Machine (UTM) equipment of Instron was used and the material was tested by the American Society for Testing and Materials. for Testing Materials, ASTM) D-882 method to determine elongation.

(5) Tensile strength

After cutting the polyimide film with a width of 10 mm and a length of 40 mm, the tensile strength was measured by the ASTM D-882 method using Instron 5564 UTM equipment from Instron. Measure the cross head speed (Cross Head Speed) at this time under the condition of 5 mm/min.

[Table 2]

With reference to Table 2, it can be confirmed that the examples satisfying the scope of the present invention are excellent in heat resistance and mechanical properties. On the contrary, it can be confirmed that the comparative example which deviates from the scope of the present invention cannot satisfy at least one of heat resistance and mechanical properties.

The above has been described with reference to the embodiments of the present invention, but those with common sense in the technical field to which the present invention belongs can make various applications and modifications within the scope of the present invention based on the above content.

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Claims (15)

A polyimide precursor composition comprising: a polyamide acid solution prepared by polymerizing more than one dianhydride monomer and more than one diamine monomer in an organic solvent; and an antioxidant, 5 wt% The decomposition temperature of the dianhydride monomer is above 380°C; and the dianhydride monomer includes a cross-linkable dianhydride compound, the cross-linkable dianhydride compound includes at least one triple bond in the molecular structure, and the antioxidant includes the following The compound represented by the chemical formula 2:

In the chemical formula 2, R _1a to R _6a are each independently selected from the group consisting of C1-C3 alkyl, aryl, carboxyl, hydroxyl, fluoroalkyl and sulfonic acid groups, and R _1a to R _6a are In the case of a plurality of them, they may be the same or different from each other, n1 is an integer from 1 to 4, and m1 to m6 are independently an integer from 0 to 3, respectively. The polyimide precursor composition described in item 1 of the scope of patent application, wherein the crosslinkable dianhydride compound is represented by the following chemical formula 1:

Here, L is a C2-C6 alkynyl group, and R ₁ and R ₂ are each independently selected from the group consisting of a C1-C3 alkyl group, an aryl group, a carboxylic acid group, a hydroxyl group, a fluoroalkyl group, and a sulfonic acid group, When R ₁ and R ₂ are plural, they may be the same as or different from each other, and n and m are each independently an integer of 0 to 3. The polyimide precursor composition described in item 2 of the scope of patent application, wherein the crosslinkable dianhydride compound is ethynyl diphthalic anhydride. The polyimide precursor composition described in item 1 of the scope of the patent application includes two or more polyimide chains with triple bonds derived from cross-linkable dianhydride compounds, which are used to achieve During the heat treatment of imidization, more than one cross-linked bond is formed by free radical reaction between the triple bonds included in different polyamide acid chains. The polyimide precursor composition as described in item 1 of the scope of the patent application, wherein based on 100 mol% of the diamine monomer, the content of the dianhydride monomer is 88 mol% to 99.5 Mole%, the content of the crosslinkable dianhydride compound is 0.5 mole% to 12 mole%. The polyimide precursor composition described in item 1 of the scope of the patent application, wherein based on 100 mol% of the diamine monomer, the content of the dianhydride monomer is 90 mol% to 99 mol% Mole%, the content of the crosslinkable dianhydride compound is 1 mole% to 10 mole%. The polyimide precursor composition according to item 6 of the scope of patent application, wherein the decomposition temperature of the 5 wt% of the antioxidant is 400° C. or more. The polyimide precursor composition described in item 1 of the scope of patent application, wherein in the chemical formula 2, n1 is 1, and m1 to m6 are 0. The polyimine precursor composition as described in item 1 of the scope of the patent application, wherein relative to 100 parts by weight of the solid content of the polyimine precursor composition, the composition includes 0.1 to 2.5 parts by weight of the Antioxidants. The polyimine precursor composition as described in item 1 of the scope of the patent application, wherein, relative to 100 parts by weight of the solid content of the polyimine precursor composition, the composition includes 0.1 to 2 parts by weight of the Antioxidants. A polyimide film is prepared from the polyimide precursor composition as described in any one of items 1 to 10 in the scope of the patent application. The polyimide film described in item 11 of the scope of patent application has a thermal decomposition temperature of 550°C to 620°C for 1% by weight, a coefficient of thermal expansion of 2.0 ppm/°C to 8.0 ppm/°C, and a glass transition temperature of 400°C. Above, the elongation is 13% or more, the tensile strength is 270 MPa or more, and the thickness is 10 μm to 20 μm. The polyimide film described in item 12 of the scope of patent application has a glass transition temperature of 417°C or higher. A method for preparing a polyimide film as described in item 11 of the scope of patent application, comprising: (a) putting more than one dianhydride monomer and more than one diamine monomer into an organic solvent for polymerization to prepare a polyimide film The process of preparing a polyimide precursor composition by mixing an antioxidant in the polyamide acid solution; and (c) combining the polyimine precursor composition Film is formed on the support and dried To prepare a gel film, the gel film is imidized to prepare a polyimide film; and the dianhydride monomer includes a cross-linkable dianhydride compound, the cross-linkable dianhydride The compound includes at least one triple bond in the molecular structure. An electronic device comprising the polyimide film as described in item 11 of the scope of patent application.