Polyimide precursors and polyimide films

Abstract

This application provides a polyimide precursor that can achieve a high amide ratio even when using environmentally friendly organic solvents. Furthermore, this application provides a polyimide film that, even when using environmentally friendly organic solvents, has similar optical properties and mechanical strength to polyimide films prepared using existing organic solvents that are classified as hazardous substances.

Description

Technical Field

[0001] This application relates to a polyimide precursor and a polyimide film comprising a cured product of the aforementioned polyimide precursor. Prior Technology

[0002] Generally, polyimide (PI) is a polymer of propylene monomers formed by polymerizing dianhydrides with diamines or diisocyanates. Based on the chemical stability of the propylene ring, it possesses excellent mechanical properties such as strength, chemical resistance, weather resistance, and heat resistance. Furthermore, polyimide has attracted considerable attention as a high-performance polymer material with applications in a wide range of industries, including electronics, communications, and optics, due to its excellent electrical properties such as insulation and low dielectric constant.

[0003] Here, polyimide refers to a high heat-resistant resin prepared by polymerizing polyamide with dianhydride monomers and diamine monomers in solution, followed by ring-closure dehydration and imidization at high temperature.

[0004] On the other hand, existing polyamides are solution polymerized in organic solvents. However, most of the organic solvents used in the past, such as N-methylpyrrolidone (NMP), dimethylformamide (DMF), or N,N'-dimethylacetamide (DMAc), are classified as hazardous substances, and the purification costs for treating them are high.

[0005] Therefore, environmentally friendly solvents were tried. However, when using these solvents, the amide content of polyamide is low compared to existing organic solvents, resulting in problems such as the inability to obtain the desired light transmittance and heat resistance. Summary of the Invention

[0006] The problem that the invention aims to solve The problem this application aims to solve is to provide a polyimide precursor that can achieve a high amide ratio even when using environmentally friendly organic solvents. Furthermore, the problem this application aims to solve is to provide a polyimide film that, even when using environmentally friendly organic solvents, has similar optical properties and mechanical strength to polyimide films prepared using existing organic solvents that are classified as hazardous substances. Technical means to solve the problem

[0007] This application relates to a polyimide precursor. For example, the aforementioned polyimide precursor may be a polyimide varnish that is amide-cured by thermosetting after being applied to a coating. Because the aforementioned polyimide precursor comprises the components described below, it can provide a polyimide with excellent durability due to achieving a high amide curing rate. In this invention, the polyimide is provided in film form; therefore, the terms "polyimide" and "polyimide film" are interpreted as having the same meaning.

[0008] An exemplary polyimide precursor according to this application comprises: polyamide having polymeric units derived from dianhydride monomers and diamine monomers; an organic solvent being at least one selected from the group consisting of N,N-diethylacetamide (DEAc), N,N-diethylformamide (DEF), N-ethylpyrrolidone (NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA); and a phosphorus-based additive having a weight-average molecular weight of 400 g / mol or more.

[0009] In this specification, the term weight-average molecular weight refers to the converted value relative to standard polystyrene as determined by gel permeation chromatography (GPC).

[0010] The aforementioned phosphorus-based additives can be added after the polymerization of polyamide is complete.

[0011] The aforementioned polyamide can be formed by polymerizing dianhydride monomers and diamine monomers in the presence of the aforementioned organic solvent.

[0012] This invention selectively uses environmentally friendly organic solvents that are not classified as hazardous substances. For example, N,N-dimethylpropionic acid (DMPA) can be used as an organic solvent.

[0013] As is well known, DMPA is an environmentally friendly organic solvent that is not classified as a hazardous substance.

[0014] However, polyamides prepared using DMPA as a solvent exhibit a lower amide imidization rate compared to polyamides prepared using organic solvents such as NMP, DMF, or DMAC, which are classified as hazardous substances.

[0015] Compared with polyamides using NMP or DMAc, polyamides using DMPA produce polyamides with poor optical properties such as transmittance and poor mechanical strength properties such as elongation and thermal decomposition temperature due to their low amide imidization rate. In addition to the above physical properties, they also have surface characteristic problems such as appearance defects.

[0016] The advantage of the polyimide precursor according to the present invention is that a high polyimide conversion rate of polyamide can be achieved by using a phosphorus-based additive with a weight-average molecular weight of a specific value or higher, thereby improving the problems caused by the use of DMPA.

[0017] For example, the weight-average molecular weight of the aforementioned phosphorus-based additives can be 400 g / mol or higher, 420 g / mol or higher, 440 g / mol or higher, 460 g / mol or higher, 480 g / mol or higher, 500 g / mol or higher, 520 g / mol or higher, 540 g / mol or higher, 560 g / mol or higher, 580 g / mol or higher, 600 g / mol or higher, 620 g / mol or higher, 640 g / mol or higher, 660 g / mol or higher, or 680 g / mol or higher. The upper limit of the aforementioned weight-average molecular weight is not particularly limited; for example, it can be below 1500 g / mol, below 1400 g / mol, below 1300 g / mol, below 1200 g / mol, below 1100 g / mol, below 1000 g / mol, below 900 g / mol, below 800 g / mol, or below 700 g / mol. Polyimide films prepared within the above-mentioned weight-average molecular weight range can provide excellent amide ratio, elongation, and appearance.

[0018] On the other hand, when using phosphorus-based additives with a weight-average molecular weight of less than 400 g / mol, an excessive amount of phosphorus-based additives must be used in order to achieve a high amide content in polyamides. However, an excessive amount of phosphorus-based additives can lead to a decrease in the elongation of polyamides or appearance defects.

[0019] Therefore, it is important to use phosphorus-based additives with specific weight-average molecular weight values, and their preferred content will be explained again below.

[0020] In one example, the phosphorus-based additive described above may contain at least two phosphate groups. Phosphorus-based additives having two or more phosphate groups may have two or more phosphorus monoxide (P=O) structures within the molecule. These P=O structures can strongly interact with polyamide to promote the amide imidization rate of the polyamide. Because the phosphorus-based additive has two or more P=O structures in its molecule, only a small amount needs to be added to increase the amide imidization rate of the polyamide. Thus, polyamide with a high amide imidization rate can provide polyamide films with excellent optical properties, physical properties, and surface properties.

[0021] Specifically, the aforementioned phosphorus-based additives may include compounds represented by the following chemical formula 1.

[0022] In the above chemical formula 1, R1 to R4 are alkyl groups having 1 to 10 carbon atoms or aryl groups having 6 to 20 carbon atoms, Z is -Ra- or -Y1-Rb-Y2- or -Y3-Rc-Y4-Rd-Y5-, Ra to Rd are each independently a substituted or unsubstituted divalent aliphatic cycloalcohol, substituted or unsubstituted divalent heteroaliphatic cycloalcohol, substituted or unsubstituted divalent aromatic cycloalcohol, or substituted or unsubstituted divalent heteroaromatic cycloalcohol, and Y1 to Y5 are each independently a linker group selected from the group consisting of single bond, substituted or unsubstituted alkylene group, substituted or unsubstituted alkylidene group, substituted or unsubstituted alkenylene group, substituted or unsubstituted alkyne group, substituted or unsubstituted arylene group, -O-, -S-, -C(=O)- and -S(=O)2-, including at least one divalent substituent.

[0023] For example, R1 to R4 can be aryl groups having 6 to 20 carbon atoms, Z can be -Y1-Rb-Y2- or -Y3-Rc-Y4-Rd-Y5-, Rb to Rd can be substituted or unsubstituted divalent aryl groups, Y1, Y2, Y3 and Y5 can be -O-, and Y4 can be a single bond or a substituted or unsubstituted alkylene group.

[0024] More specifically, R1 to R4 can be phenyl, Z can be -Y1-Rb-Y2- or -Y3-Rc-Y4-Rd-Y5-, Rb to Rd can be phenylene, Y1, Y2, Y3 and Y5 can be -O-, and Y4 can be a single bond or a propenyl group.

[0025] Examples of compounds of Formula 1 that satisfy the above-mentioned weight-average molecular weight range may include bisphenol A bis(diphenyl phosphate) with a weight-average molecular weight of 692 g / mol, biphenyl-4,4'-dyltetraphenylbis(phosphate) with a weight-average molecular weight of 454 g / mol, or resorcinol bis(diphenyl phosphate) with a weight-average molecular weight of 574 g / mol. On the other hand, in the case of triphenyl phosphate, since the weight-average molecular weight is about 326 g / mol, it may not be included in the phosphorus-based additive of the present invention.

[0026] In one example, the content of the aforementioned phosphorus-based additive, based on the total amount of polyimide precursor, can range from 0.001 wt% to 0.1 wt%. For example, the lower limit of the content of the aforementioned phosphorus-based additive can be 0.005 wt%, 0.01 wt%, 0.015 wt%, 0.016 wt%, 0.017 wt%, 0.018 wt%, 0.019 wt%, 0.02 wt%, 0.025 wt%, 0.03 wt%, 0.035 wt%, 0.04 wt%, or 0.045 wt%. With phosphorus-based additives having a weight-average molecular weight less than 400 g / mol, a content exceeding 0.1 wt% is necessary to obtain a high polyimide conversion rate. However, a phosphorus-based additive content exceeding 0.1 wt% may lead to problems such as reduced elongation of the polyimide or appearance defects, and is therefore not preferred.

[0027] In one embodiment, there are no particular limitations on the dianhydride monomer as long as it can react with the diamine monomer to form polyimide. For example, the dianhydride monomer according to the present invention may include at least one selected from the group consisting of pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), oxydiphenyl dianhydride (ODPA), 4,4-(hexafluoroisopropylidene)diphenyl dianhydride (6-FDA), and p-phenylenebis(triphenyl dianhydride) (TAHQ).

[0028] Considering compatibility with the aforementioned organic solvents, the dianhydride monomers are preferably pyromellitic dianhydride (PMDA), 4,4-(hexafluoroisopropylidene)diphenyl dianhydride (6-FDA), oxydiphenyl dianhydride (ODPA), or 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and particularly preferably 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA).

[0029] In this specification, unless otherwise specified, the term "substitution" may refer to the substitution of at least one hydrogen atom in a molecule by a polar functional group such as alkyl, halogen, alkylamine, alkylamide, hydroxyl, alkoxy, thiol or thiol ether, and two or more substituents may be linked together to form a ring.

[0030] In this specification, unless otherwise specified, the term "aliphatic cyclic group" may refer to an aliphatic cyclic group having 3 to 30 carbon atoms, 4 to 25 carbon atoms, 5 to 20 carbon atoms, and 6 to 16 carbon atoms. For example, specific examples of tetravalent aliphatic cyclic groups include groups obtained by removing four hydrogen atoms from the rings of cyclohexane, cycloheptane, cyclodecane, cyclododecane, norbornane, isoboronane, adamantane, cyclododecane, and bicyclopentane.

[0031] In this specification, unless otherwise specified, the term "aromatic cyclogroup" may refer to an aromatic cyclogroup having 4 to 30 carbon atoms, 5 to 25 carbon atoms, 6 to 20 carbon atoms, and 6 to 16 carbon atoms. The aforementioned aromatic cyclogroups may be monocyclic or fused rings. For example, examples of tetravalent aromatic hydrocarbon cyclogroups include groups obtained by removing four hydrogen atoms from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetraphenylene ring, or pyrene ring.

[0032] In this specification, the term "aryl" may refer to a divalent organic group derived from the aforementioned aromatic cyclic groups.

[0033] In this specification, the term "heterocyclic group" includes heteroaliphatic cyclic groups and heteroaromatic cyclic groups.

[0034] As used herein, the term "heteroaliphatic cyclogroup" can refer to a cyclogroup in which at least one carbon atom of the aforementioned aliphatic cyclogroup is substituted with at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur and phosphorus.

[0035] In this specification, unless otherwise specified, the term "heteroaromatic cyclogroup" may refer to a cyclogroup in which at least one carbon atom of the aforementioned aromatic cyclogroup is substituted by at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus. The aforementioned heteroaromatic cyclogroup may be a monocyclic or fused ring.

[0036] The aforementioned aliphatic cyclogroup, heteroaliphatic cyclogroup, aromatic cyclogroup, or heteroaromatic cyclogroup may each be independently substituted by at least one substituent selected from the group consisting of halogen, hydroxyl, carboxyl, halogen-substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and alkoxy group having 1 to 4 carbon atoms.

[0037] In this specification, the term "single bond" may refer to a bond that connects two atoms in a state where there are no atoms present.

[0038] In this specification, unless otherwise specified, the term "alkyl" may refer to an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The aforementioned alkyl groups may have a straight-chain, branched, or cyclic structure and may optionally be substituted with one or more substituents. For example, the aforementioned substituents may be polar functional groups such as at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether groups.

[0039] In this specification, unless otherwise specified, the term "alkenyl" may refer to an alkenyl group having 2 to 30 carbon atoms, 2 to 25 carbon atoms, 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms. The aforementioned alkenyl groups may have a straight-chain, branched, or cyclic structure, and may optionally be substituted by one or more substituents. For example, the aforementioned substituents may be polar functional groups such as at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether groups.

[0040] In this specification, unless otherwise specified, the term "alkynyl" may refer to an alkynyl group having 2 to 30 carbon atoms, 2 to 25 carbon atoms, 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms. The aforementioned alkynyl group may have a straight-chain, branched, or cyclic structure, and may optionally be substituted by one or more substituents. For example, the aforementioned substituents may be polar functional groups such as at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether groups.

[0041] In this specification, unless otherwise specified, the term "alkylene" may refer to an alkylene having 2 to 30 carbon atoms, 2 to 25 carbon atoms, 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 10 carbon atoms, or 2 to 8 carbon atoms. The aforementioned alkylene groups are divalent organic groups with two hydrogen atoms removed from different carbon atoms, and may have a straight-chain, branched, or cyclic structure, and may optionally be substituted by one or more substituents. For example, the aforementioned substituents may be polar functional groups such as at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether groups.

[0042] In this specification, unless otherwise specified, the term "alkylidene" may refer to an alkylidene group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 10 carbon atoms, or 1 to 8 carbon atoms. The aforementioned alkylidene group is a divalent organic group having two hydrogen atoms removed from one carbon atom, and may have a straight-chain, branched, or cyclic structure, and may optionally be substituted by one or more substituents. For example, the aforementioned substituents may be polar functional groups such as at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether groups.

[0043] In this specification, unless otherwise specified, the term "alkoxy" may refer to an alkoxy group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The aforementioned alkoxy group may include an alkyl group having a straight-chain, branched, or cyclic structure, and the aforementioned alkyl group may optionally be substituted with one or more substituents. For example, the aforementioned substituent may be at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether.

[0044] In this specification, unless otherwise specified, the term "alkylamine" includes monoalkylamine (-NHR) or dialkylamine (-NR2), wherein R can independently refer to an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The aforementioned alkyl group can include alkyl groups having a straight-chain, branched, or cyclic structure, and can optionally be substituted with one or more substituents. For example, the aforementioned substituents can be at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether.

[0045] In this specification, unless otherwise specified, the term "alkylamide" includes monoalkylamide (-C(O)NHR) or dialkylamide (-C(O)NR2), wherein R can independently refer to an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The alkyl group may include alkyl groups having a straight-chain, branched, or cyclic structure, and may optionally be substituted with one or more substituents. For example, the substituent may be at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether.

[0046] In this specification, unless otherwise specified, the terms "thiol ether group" or "sulfide" may refer to -SR, wherein R may independently refer to an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The aforementioned alkyl group may include alkyl groups having a straight-chain, branched, or cyclic structure, and may optionally be substituted with one or more substituents. For example, the aforementioned substituents may be at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol group, or thiol ether group.

[0047] In this specification, unless otherwise specified, the term "alkylene" may refer to -S(O)R, wherein R may independently refer to an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The aforementioned alkyl group may include alkyl groups having a straight-chain, branched, or cyclic structure, and may optionally be substituted with one or more substituents. For example, the aforementioned substituents may be at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether groups.

[0048] In this specification, unless otherwise specified, the term "carbonyl" may refer to -C(O)R, wherein R may independently refer to an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The aforementioned alkyl group may include alkyl groups having a straight-chain, branched, or cyclic structure, and may optionally be substituted with one or more substituents. For example, the aforementioned substituents may be at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether groups.

[0049] In this specification, unless otherwise specified, the term "ester" may refer to -C(O)OR or -OC(O)R, wherein R may independently refer to an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The aforementioned alkyl group may include alkyl groups having a straight-chain, branched, or cyclic structure, and may optionally be substituted with one or more substituents. For example, the aforementioned substituents may be at least one substituent selected from the group consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether groups.

[0050] As an example, there are no particular restrictions on the diamine monomer mentioned above, as long as it can react with the dianhydride monomer to form polyamide. For example, the diamine monomer according to the present invention may include at least one selected from the group consisting of 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenyl ether (ODA), 4,4'-methylenediamine (MDA), 4,4'-diaminobenzylaniline (4,4-DABA), N,N-bis(4-aminophenyl)benzyl-1,4-dimethylamine (BPTPA), 2,2-dimethylbenzidine (M-TOLIDINE), 2,2-bis(trifluoromethyl)benzidine (TFDB), 1,4-diaminophenoxybenzene (TPE-Q), diaminophenoxybenzene (TPE-R), 2,2-diaminophenoxyphenylpropane (BAPP), and 2,2-diaminophenoxyphenylhexafluoropropane (HFBAPP).

[0051] Considering the compatibility with the aforementioned organic solvents and dianhydride monomers, the diamine monomers are preferably 1,4-diaminobenzene (PPD), 4,4'-diaminodiphenyl ether (or oxybisphenylamine, ODA), 3,5-diaminobenzoic acid (or DABA), 2,2'-bis(trifluoromethyl)benzidine (TFMB), 2,2-diaminophenoxyphenyl hexafluoropropane (HFBAPP) or 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and particularly preferably 1,4-diaminobenzene (PPD).

[0052] As another example, the diamine monomer described above may include at least one compound represented by the following chemical formula 2.

[0053] In the above chemical formula 2, one of B1 to B5 is an amino group (-NH2), -R-NH2 or -OR-NH2, where R is a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylidene group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkyne group, or a substituted or unsubstituted aryl group, and the remainder is hydrogen, halogen, hydroxyl, carboxyl or an alkyl group substituted or unsubstituted by halogen.

[0054] In addition, the diamine monomers that can be used to prepare polyamide solutions are aromatic diamines, which can be classified as follows and illustrated with examples.

[0055] 1) As a diamine having a benzene core in its structure, such as 1,4-diaminobenzene (or p-phenylenediamine, PPD), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, or 3,5-diaminobenzoic acid (or DABA), a diamine with a relatively rigid structure;

[0056] 2) Examples of diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or oxydiphenylamine, ODA) and 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3 3',5,5'-Tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzaniline, 3,3'-dichlorobenzaniline, 3,3'-dimethylbenzaniline (or o-benzaniline), 2,2'-dimethylbenzaniline (or m-toluidine), 3,3'-dimethoxybenzaniline, 2,2'-dimethoxybenzaniline, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether Benzene sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodibenzophenone, 4,4'-diaminodibenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane Diamines having two benzene rings in their structure, such as methane, 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'-diaminodiphenylene, 3,4'-diaminodiphenylene, 2,2'-bis(trifluoromethyl)benzidine (TFMB), or 4,4'-diaminodiphenylene.

[0057] 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'-di (4-Phenylenoxy)benzophenone, 1,3-bis(3-aminophenyl sulfide)benzene, 1,3-bis(4-aminophenyl sulfide)benzene, 1,4-bis(4-aminophenyl sulfide)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 or 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, etc., are diamines having three benzene nuclei in their structure;

[0058] 4) Examples include 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)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]one, bis[3-(4-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy)phenyl]benzene [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] sulfide, bis[3-(4-aminophenoxy)phenyl] sulfide, bis[4-(3-aminophenoxy)phenyl] sulfide, bis[4- [4-aminophenoxy)phenyl] monoxide, 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-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane Diamines having four benzene rings in their structure, such as 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, or 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

[0059] The above-mentioned diamine monomers can be used alone or in combination of two or more as needed. For example, as the above-mentioned diamine monomers, one or more combinations of the group selected from 1,4-diaminobenzene (PPD), 4,4'-diaminodiphenyl ether (or oxydiphenylamine, ODA), 3,5-diaminobenzoic acid (or DABA), 2,2'-bis(trifluoromethyl)benzidine (TFMB), 2,2-diaminophenoxyphenyl hexafluoropropane (HFBAPP) and 2,2-bis[4-(4-aminophenoxy))phenyl]propane (BAPP) can be used.

[0060] In one example, the content of dianhydride monomer can range from 90 mol% to 100 mol% relative to 100 mol% of diamine monomer. For instance, the content of dianhydride monomer can range from 91 mol% to 100 mol%, 92 mol% to 100 mol%, 93 mol% to 100 mol%, 94 mol% to 100 mol%, 95 mol% to 100 mol%, 96 mol% to 100 mol%, 97 mol% to 100 mol%, 98 mol% to 100 mol%, 98.5 mol% to 100 mol%, or 98.9 mol% to 100 mol% relative to 100 mol% of diamine monomer.

[0061] In one embodiment, the solid content of the polyamide composition can be from 5% to 40% by weight, 10% to 30% by weight, or 15% to 20% by weight, based on the total weight. This application controls viscosity increase by adjusting the solid content of the polyamide composition and prevents increases in manufacturing costs and processing time required to remove large amounts of solvent during curing.

[0062] The polyamide composition of this application can possess low viscosity characteristics while including high molecular weight polyamide. The viscosity of the polyamide composition of this application, measured at 23°C and a shear rate of 1 s⁻¹, can be below 50,000 cP, 40,000 cP, 30,000 cP, 20,000 cP, 10,000 cP, 9,000 cP, 5,000 cP, 4,000 cP, or 3,000 cP. The lower limit is not particularly limited, but can be above 500 cP or above 1,000 cP. In one embodiment, the viscosity of the polyamide composition of this application can be in the range of 500 cP to 10,000 cP. For example, the above viscosity can be measured using a Haake MARS40 at 23°C. By adjusting the above viscosity range, this application can provide a polyamide composition with excellent processability and convenient product application.

[0063] This application also relates to polyimide films comprising a cured product of the aforementioned polyimide precursor. The aforementioned polyimide film can be formed by thermosetting the polyimide precursor to a amide form. There are no particular limitations on the thermosetting conditions, but it can be carried out in a temperature range of 100°C to 400°C.

[0064] As described above, the polyimide precursor containing both an organic solvent including DMPA and a phosphorus-based additive having a weight-average molecular weight of a certain value improves the low amide content of polyamide prepared using only DMPA solvent. Therefore, the polyimide film according to this application containing its cured product can ensure a level of physical properties similar to those of polyimide films using solvents such as NMP or DMAc.

[0065] For example, the amide content of the aforementioned polyimide film can be in the range of 92% to 99%. For example, the lower limit of the aforementioned amide content can be 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, or 98% or more.

[0066] The amide ratio was analyzed using the attenuated total reflection (ATR) method with a Bruker ALPHA-P infrared spectrometer (IR). The strength of the amide bonds calculated by IR analysis is expressed as a percentage. The CN tensile strength (1375 cm⁻¹)₀ and C=C tensile strength (1498 cm⁻¹)₀ of a fully amide-imidized polyamide film (100% amide ratio) are used as reference values, and the ratios to the CN tensile strength (1375 cm⁻¹)* and C=C tensile strength (1498 cm⁻¹)* of a polyamide film prepared by amide-imidizing the polyamide precursor according to the present invention are expressed as a percentage. Specifically, the amide ratio can be calculated using Equation 1 below. [General Form 1] Acrylimide rate (%) = {(1375cm-1)* / (1498cm-1)*} / {(1375cm-1)0 / (1498cm-1)0}×100

[0067] Furthermore, the 1% thermal decomposition temperature (td) of the aforementioned polyimide film, determined using a Thermogravimetric analysis (TGA) apparatus, can be within the ranges of 300°C to 600°C, 350°C to 600°C, 400°C to 600°C, 450°C to 600°C, 500°C to 600°C, or 550°C to 600°C. The aforementioned 1% thermal decomposition temperature (td) can be determined by removing moisture from the film at 150°C using a TGA apparatus and then heating the film to 600°C at a heating rate of 10°C / min. Polyimide films meeting the aforementioned 1% thermal decomposition temperature (Td) can be considered to have excellent mechanical strength.

[0068] In one example, the aforementioned polyimide film can have an average transmittance of over 60% for a thickness of 10 μm at wavelengths from 380 nm to 780 nm. For example, the average transmittance can be over 61%, 62%, 63%, 64%, 65%, 66%, or 67%, with no particular upper limit, but it can be below 90%. The aforementioned average transmittance can be measured using a UV-Vis spectrophotometer, for example, a colorimeter from Hunter Labs.

[0069] In one embodiment, the elongation of the polyimide film, as measured according to ASTM D-1708, can be 10% or more, 11% or more, 12% or more, 13% or more, 14% or more, 15% or more, 9% or more, or 10% or more. The upper limit is not particularly limited, but can be less than 30%, less than 25%, or less than 20%. The above elongation can be measured using an Instron UTM device from Instron Corporation. Compared with the efficacy of previous technologies

[0070] This application provides a polyimide precursor that can achieve a high amide ratio even when using DMPA as an environmentally friendly organic solvent, and also provides a polyimide film that has similar optical properties and mechanical strength to polyimide films prepared using NMP or DMAc as solvents, even when using DMPA as an environmentally friendly organic solvent. Implementation

[0071] Although this application will be specifically described through the following embodiments, the scope of this application is not limited to the following embodiments. [Example] [1] [ ]

[0072] In a 500 mL glass reaction vessel equipped with a stirrer, nitrogen inlet pipe, and exhaust pipe, N,N-dimethylpropionic acid (DMPA) was added as an organic solvent, along with 100 mol% of 1,4-diaminobenzene (PPD) and 98.9 mol% of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA). The polymerization reaction was then carried out at 25°C for 16 hours to prepare a polyamide solution with a solid content of 15%. Bisphenol A bis(diphenyl phosphate) (BDP) was then added to the polyamide solution at a weight ratio of 0.02% relative to the polyamide solution, and the mixture was stirred for 2 hours to prepare the polyimide precursor.

[0073] In addition, a polyimide film was prepared by thermosetting the above-mentioned polyimide precursor from 100°C to 460°C at a heating rate of 5°C / min (film thickness is shown in Table 2 below). [Example] [2] [To the Example] [9] [ ]

[0074] Except for the composition shown in Table 1 below, the polyimide precursor and the polyimide film formed therefrom were prepared by the same method as in Example 1. [Comparative Example] [1] [To the comparative example] [7] [ ]

[0075] Except for the composition shown in Table 1 below, the polyimide precursor and the polyimide film formed therefrom were prepared by the same method as in Example 1. [ ] [Experimental Example] [1-] [Appearance Evaluation] [ ] [ ]

[0076] The appearance of the polyimide films prepared in the examples and comparative examples was observed with the naked eye, and the appearance was evaluated according to the following criteria. The results are shown in Table 2 below. ○: No bubbles (excellent surface properties) △: 5 or fewer bubbles are produced (average surface properties) ×: More than 5 bubbles were generated (poor surface properties) [Experimental Example] [2-1%] [Thermal decomposition temperature] [(1%Td)] [ ]

[0077] To determine the 1% thermal decomposition temperature of the polyimide films prepared in the examples and comparative examples, thermogravimetric analysis was performed using TA Instruments. (thermogravimetric analysis) The Q50 model was used to raise the temperature of the polyimide film to 150°C in a nitrogen atmosphere at a rate of 10°C / min, and then held isothermally for 30 minutes to remove moisture. Subsequently, the temperature was raised to 600°C at a rate of 10°C / min to determine the temperature at which a 1% weight loss occurred. The results are shown in Table 2 below. [Experimental Example] [3-] Average light transmittance [ ] [ ]

[0078] The average transmittance of the polyimide films prepared in the Examples and Comparative Examples at wavelengths from 380 nm to 780 nm was measured using a colorimeter from Hunter Labs, and the results are shown in Table 2 below. [Experimental Example] [4-] [Elongation] [ ] [ ]

[0079] The elongation of the polyimide films prepared in the examples and comparative examples was determined using an Instron UTM instrument from Instron Corporation according to ASTM D-1708 method, and the results are shown in Table 2 below. [Experimental Example] [5-] [Acyl] [Sub-] [Amine] [Conversion Rate] [ ] [ ] <00?0330> The above acylation rate was analyzed by the Attenuated Total Reflectance (ATR) method using a Bruker ALPHA-P Infrared Spectrometer (IR). The intensity of the imide bond calculated by IR analysis is expressed as a percentage, taking the C-N stretching intensity (1375 cm-1)0 and C-N stretching intensity (1498 cm-1)0 of the fully imidized polyimide film (imide rate 100%) as the reference, and expressing the ratio of the C-N stretching intensity (1375 cm-1)* and C=C stretching intensity (1498 cm-1)* of the polyimide films prepared in the examples and comparative examples as a percentage. Specifically, the above acylation rate can be calculated using Equation 1 below. [General Formula 1] Acylation Rate (%) = {(1375 cm-1)* / (1498 cm-1)*} / {(1375 cm-1)0 / (1498 cm-1)0} × 100 <00?0339>

[0081] Referring to Table 1 and Table 2 above, in the case of Examples 1 to 9 using the environmentally friendly solvent DMPA and a phosphorus-based additive with a weight average molecular weight of 400 g / mol or more, the appearance is excellent, the average light transmittance at wavelengths from 380 nm to 780 nm is 60% or more, the elongation rate measured according to ASTM D-1708 is 13% or more, and the acylation rate is 94% or more.

[0082] On the other hand, in Comparative Example 3, which used DMPA but not phosphorus-based additives, the amide content was 92%, which was low, and the average transmittance was 59%, which was also low. In addition, in Comparative Examples 4 to 7, which used DMPA and phosphorus-based additives with a weight-average molecular weight of less than 400 g / mol, the elongation was less than 12%, which was also low. In particular, Comparative Examples 6 and 7 had appearance defects.

[0083] Therefore, according to embodiments of the present invention, when DMPA, as an environmentally friendly solvent, and a phosphorus-based additive with a weight-average molecular weight of 400 g / mol or more are used simultaneously, the amide ratio and elongation are improved, thereby providing a polyamide precursor with excellent optical properties and durability. Without departing from the technical concept of this invention, those skilled in the art can make various substitutions and modifications to the invention described above, and therefore this invention is not limited to the embodiments described above.

Claims

1. A polyimide precursor, comprising: Polyamide has polymeric units derived from dianhydride monomers and diamine monomers; An organic solvent, which is at least one selected from the group consisting of dimethylpropionamide (DMPA) and diethylpropionamide (DEPA); and a phosphorus-based additive having a weight-average molecular weight of 400 g / mol or more, wherein the content of the phosphorus-based additive is from 0.001% by weight to 0.1% by weight based on the total weight of the polyimide precursor.

2. The polyimide precursor of claim 1, wherein, The aforementioned phosphorus-based additives include at least two phosphate groups.

3. The polyimide precursor as claimed in claim 1, wherein, The aforementioned phosphorus-based additives include compounds of the following chemical formula 1: In the aforementioned chemical formula 1, R1 to R4 are alkyl groups having 1 to 10 carbon atoms or aryl groups having 6 to 20 carbon atoms, Z is -Ra- or -Y1-Rb-Y2- or -Y3-Rc-Y4-Rd-Y5-, Ra to Rd are each independently a substituted or unsubstituted divalent aliphatic cyclogroup, a substituted or unsubstituted divalent heteroaliphatic cyclogroup, a substituted or unsubstituted divalent aromatic cyclogroup, or a substituted or unsubstituted divalent heteroaromatic cyclogroup, Y1 to Y5 are each independently a linker group selected from the group consisting of single bond, substituted or unsubstituted alkylene group, substituted or unsubstituted alkylidene group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkyne group, substituted or unsubstituted arylene group, -O-, -S-, -C(=O)- and -S(=O)2-, including at least one divalent substituent.

4. The polyimide precursor of claim 1, wherein, The aforementioned dianhydride monomers include at least one selected from the group consisting of pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), oxydiphenyl dianhydride (ODPA), 4,4-(hexafluoroisopropylidene)diphenyl dianhydride (6-FDA), and p-phenylenebis(triphenylene anhydride) (TAHQ).

5. The polyimide precursor as claimed in claim 1, wherein, The aforementioned diamine monomer includes at least one selected from the group consisting of 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenyl ether (ODA), 4,4'-methylenediamine (MDA), 4,4'-diaminobenzylaniline (4,4-DABA), N,N-bis(4-aminophenyl)phenyl-1,4-dimethylamine (BPTPA), 2,2-dimethylbenzidine (M-TOLIDINE), 2,2-bis(trifluoromethyl)benzidine (TFDB), 1,4-diaminophenoxybenzene (TPE-Q), diaminophenoxybenzene (TPE-R), 2,2-diaminophenoxyphenylpropane (BAPP), and 2,2-diaminophenoxyphenylhexafluoropropane (HFBAPP).

6. A polyimide film comprising a cured product of the polyimide precursor as claimed in claim 1.

7. The polyimide film as claimed in claim 6, wherein, The amide content is in the range of 92% to 99%.

8. The polyimide film as claimed in claim 6, wherein, The 1% thermal decomposition temperature Td, determined using a thermogravimetric analyzer, is in the range of 300°C to 600°C.

9. The polyimide film as claimed in claim 6, wherein, The average transmittance is over 60% in the wavelength range of 380nm to 780nm.

10. The polyimide film as claimed in claim 6, wherein, The elongation, as determined by ASTM D1708, is greater than 10%.

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