Low-viscosity polyamic acid composition

Abstract

The present invention provides a polyamic acid composition comprising: a polyamic acid including a dianhydride and a diamine as polymerization units; and a solvent, wherein, on the basis of 100 mol % of the total content of the dianhydride, the polyamic acid composition comprises 82-100 mol% of pyromellitic dianhydride (PMDA), and the diamine includes 2,2'-bis (4-aminophenoxyphenyl) propane (BAPP), the viscosity of the polyamic acid composition, as measured at a temperature of 30 °C and a shear rate of 1s-1, is 150 cP or less, and the solid content of the polyamic acid composition is less than 8 wt%.

Description

Low-viscosity polyamic acid composition

[0001] The present invention relates to a low-viscosity polyamic acid composition. More specifically, it relates to a polyamic acid composition having low viscosity and excellent adhesion to a substrate.

[0002] Generally, polyimide (PI) resin refers to a high-heat-resistant resin produced by solution polymerizing a dianhydride with a diamine or diisocyanate to produce a polyamic acid derivative, and then dehydrating it at high temperatures to form an imide. As an insoluble and infusible ultra-high-heat-resistant resin, polyimide resin possesses excellent properties such as heat oxidation resistance, heat resistance, radiation resistance, low-temperature properties, and chemical resistance. Consequently, it is widely used in advanced heat-resistant materials such as automotive materials, aerospace materials, and spacecraft materials, as well as in electronic materials such as insulating coatings, insulating films, semiconductors, and electrode protective films for TFT-LCDs. Recently, it has also been utilized in display materials such as optical fibers and liquid crystal alignment films, and in transparent electrode films by containing conductive fillers within the film or coating the surface. Such polyimide resin can be utilized as an adhesive by applying a polyamic acid-containing solution, which serves as a precursor, to a target object in the form of a thin film and then curing it through the action of heat and / or chemical catalysts.

[0003] However, generally speaking, polyimide resins are not considered to have high adhesive strength among polymer resins, and various studies are being conducted to further improve their adhesive strength.

[0004] Therefore, there is a need for a novel polyimide resin that possesses superior adhesion compared to conventional resins while also ensuring appropriate mechanical properties.

[0005] The present invention provides a polyamic acid composition having low viscosity and excellent adhesion to a substrate, and a method for manufacturing the same.

[0006] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be illustrated and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0007] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0008] Where in this specification, when a quantity, concentration, or other value or parameter is given as an enumeration of a range, a preferred range, a preferred upper limit, and a preferred lower limit, it should be understood that any pair of any upper range limit or preferred value and any lower range limit or preferred value are specifically disclosed, regardless of whether the range is disclosed separately.

[0009] Where a range of numerical values ​​is mentioned in this specification, unless otherwise stated, the range and the scope of all inventions within that range are not intended to be limited to the specific value mentioned when defining the range.

[0010] In this specification, "dianhydride" is intended to include its precursor or derivative, and is also referred to as "dianhydric acid," "dianhydride," or "acid dianhydride." Although these may not technically be dianhydrides, they will nevertheless react with a diamine to form a polyamic acid, which can then be converted into a polyimide.

[0011] In this specification, "diamine" is intended to include its precursors or derivatives, which may not technically be diamines but nevertheless will react with dianhydric acid to form a polyamic acid, which can then be converted into a polyimide.

[0012] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application. Specific details for the implementation of the above invention are described below.

[0013] The present invention relates to a low-viscosity polyamic acid composition and a method for manufacturing the same.

[0014] Polyamic acid composition and method for preparing the same

[0015] The present invention relates to a polyamic acid composition comprising: a polyamic acid comprising dianhydride and a diamine as polymerization units; and a solvent, wherein, based on a total content of 100 mol% of the dianhydride, the composition comprises 82 to 100 mol% of pyromellitic dianhydride (PMDA), and the diamine comprises 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP), and is subjected to a temperature of 30°C and 1s-1 A polyamic acid composition is provided in which the viscosity of the polyamic acid composition measured at a shear rate is 150 cP or less, and the solid content of the polyamic acid composition is less than 8 wt%.

[0016] Specifically, the polyamic acid composition is at a temperature of 30°C and 1s -1 The viscosity measured under the shear rate conditions may be in the range of 5 cP to 150 cP. Preferably, the lower limit of the viscosity of the polyamic acid composition may be 7 cP or more, 10 cP or more, 15 cP or more, 20 cP or more, 23 cP or more, 25 cP or more, 27 cP or more, 30 cP or more, 33 cP or more, or 35 cP or more, and the upper limit may be 145 cP or less, 140 cP or less, 135 cP or less, 130 cP or less, 125 cP or less, 120 cP or less, 115 cP or less, 110 cP or less, 105 cP or less, or 100 cP or less.

[0017] In addition, by controlling the viscosity of the above polyamic acid composition to be low at 150 cP or less, it is possible to manufacture a polyimide with desired properties having excellent processability and workability, and it can be used in various applications requiring spray coating and low-viscosity polyamic acid compositions. In particular, the lower the viscosity, the faster the coating (impregnation) speed on the substrate, enabling rapid coating (impregnation).

[0018] Specifically, the solid content of the above polyamic acid composition may be 1 wt% or more and less than 8 wt%. Here, solid content refers to the weight of the monomer added to the total polyamic acid composition when substantially equimolar amounts of diamine and dianhydride are added. Preferably, the lower limit of the solid content of the polyamic acid composition may be 1.5 wt% or more, 2 wt% or more, 2.5 wt% or more, 3 wt% or more, or 3.5 wt% or more, and the upper limit may be 7.9 wt% or less, 7.5 wt% or less, 7.3 wt% or less, 7.0 wt% or less, 6.8 wt% or less, or 6.5 wt% or less. In addition, by controlling the solid content of the above polyamic acid composition, the increase in viscosity can be controlled and the imidization time at high temperatures during the curing process can be shortened. Furthermore, the desired coating thickness can be determined by controlling the solid content, and the lower the solid content, the thinner the coating layer can be achieved in a single coating.

[0019] Specifically, the polyamic acid may contain 82 to 100 mol% of pyromellitic dianhydride (PMDA) based on 100 mol% of the total content of the dianhydride, and preferably, the lower limit may be 82.5 mol% or more, 83.0 mol% or more, 83.5 mol% or more, 84.0 mol% or more, 84.5 mol% or more, or 85.0 mol% or more, and the upper limit may be 100 mol% or less.

[0020] In addition, the polyamic acid may further include 0 to 18 mol% of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) based on 100 mol% of the total content of the dianhydride. Here, 0 mol% may mean that 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) is not included in the polyamic acid composition. Preferably, the upper limit may be 17.5 mol% or less, 17.0 mol% or less, 16.5 mol% or less, 16.0 mol% or less, 15.5 mol% or less, or 15.0 mol% or less, and the lower limit may be 0 mol% or more.

[0021] In addition, the polyamic acid may contain 45 to 100 mol% of 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) based on 100 mol% of the total content of the diamine, and preferably, the lower limit may be 45.5 mol% or more, 46.0 mol% or more, 46.5 mol% or more, 47.0 mol% or more, 47.5 mol% or more, 48.0 mol% or more, 48.5 mol% or more, 49.0 mol% or more, 49.5 mol% or more, or 50.0 mol% or more, and the upper limit may be 100 mol% or less.

[0022] In addition, the above diamine may further include one or more selected from the group consisting of paraphenylenediamine (PPD), 4,4'-diaminodiphenyl ether (ODA), metaphenylenediamine (MPD), and 1,3-bis(4-aminophenoxy)benzene (TPE-R).

[0023] In addition, the polyamic acid may further contain 0 to 55 mol% of one or more selected from the group consisting of paraphenylenediamine (PPD), 4,4'-diaminodiphenyl ether (ODA), metaphenylenediamine (MPD), and 1,3-bis(4-aminophenoxy)benzene (TPE-R), based on the total content of the diamine at 100 mol%. Preferably, the upper limit may be 54.5 mol% or less, 54.0 mol% or less, 53.5 mol% or less, 53.0 mol% or less, 52.5 mol% or less, 52.0 mol% or less, 51.5 mol% or less, 51.0 mol% or less, 50.5 mol% or less, or 50.0 mol% or less, and the lower limit may be 0 mol% or more. Here, 0 mol% may mean that one or more selected from the group consisting of paraphenylenediamine (PPD), 4,4'-diaminodiphenyl ether (ODA), metaphenylenediamine (MPD), and 1,3-bis(4-aminophenoxy)benzene (TPE-R) are not included in the polyamic acid composition.

[0024] In addition, the polyamic acid may include pyromellitic dianhydride (PMDA) and 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) as polymerization units, or pyromellitic dianhydride (PMDA), 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) and 4,4'-diaminodiphenyl ether (ODA) as polymerization units, or pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) as polymerization units.

[0025] Specifically, the above polyamic acid is

[0026] 1) Containing 100 mol% of pyromellitic dianhydride (PMDA) and 100 mol% of 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) as polymerization units, or

[0027] 2) comprising 100 mol% pyromellitic dianhydride (PMDA), 50 mol% 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP), and 50 mol% 4,4'-diaminodiphenyl ether (ODA) as polymerization units, or

[0028] 3) It may contain 85 mol% of pyromellitic dianhydride (PMDA), 15 mol% of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and 100 mol% of 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) as polymerization units.

[0029] In addition, the above solvent is not particularly limited as long as it is an organic solvent in which polyamic acid can be dissolved, but as an example, it may be an aprotic polar solvent.

[0030] Specifically, the solvent may include one or more selected from the group consisting of N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), N,N'-dimethylpropanamide (DMPA), N,N-diethylacetamide (DEAc), dimethyl sulfoxide (DMSO), 3-methoxy-N,N-dimethylpropanamide, p-chlorophenol, o-chlorophenol, gamma-butyrolactone (GBL), diglyme, and naphthalene, and preferably may include one or more selected from the group consisting of N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO).

[0031] The above solvent may include a first solvent and a second solvent, and the first solvent and the second solvent may be the same or different from each other.

[0032] In addition, the first solvent may be a reaction solvent, and the second solvent may be a dilution solvent.

[0033] In addition, the present invention can control the solid content or viscosity of the polyamic acid composition by adding a diluent solvent to the polyamic acid composition.

[0034] The weight-average molecular weight (Mw) of the above polyamic acid may be 100,000 to 200,000 g / mol. Specifically, the lower limit of the weight-average molecular weight may be 101,000 g / mol, 103,000 g / mol, 105,000 g / mol, 107,000 g / mol, 110,000 g / mol, 115,000 g / mol, 118,000 g / mol, or 120,000 g / mol or higher, and the upper limit of the weight-average molecular weight may be 195,000 g / mol, 192,000 g / mol, 190,000 g / mol, 187,000 g / mol, 185,000 g / mol, 183,000 g / mol, 180,000 g / mol, 178,000 g / mol, or 175,000 g / mol or lower. Here, the weight-average molecular weight refers to a converted value relative to standard polystyrene measured by GPC (Gel permeation Chromatograph). By controlling the weight-average molecular weight to the above range, polyimide with excellent processability and desired physical properties can be manufactured.

[0035] In the present invention, the adhesive strength was confirmed through the Crosscut Test, which is primarily used as a criterion for determining the adhesiveness of the polyimide.

[0036] Specifically, after curing the above polyamic acid composition, the adhesion strength according to ASTM D 3359 may be 4B or higher, and specifically, when measuring the adhesion strength on a substrate according to ASTM D 3359, the removed area may be less than 5% of the total.

[0037] Specifically, the cured product of the above polyamic acid composition may have an adhesion strength of 4B or higher according to ASTM D 3359. Specifically, when measuring the adhesion strength of the cured product of the above polyamic acid composition according to ASTM D 3359, the removed area may be less than 5% of the total. Here, the substrate may be one or more selected from the group consisting of SUS (Stainless Steel) substrates, glass substrates, ceramic substrates, and silicon substrates.

[0038] At this time, the adhesion strength was measured using the method specified in ASTM D 3359. Specifically, the surface of the polyimide adhered to the substrate was cut along a cross cutter guide to form a grid pattern, and a tape was applied to and removed from the grid pattern. The adhesion strength was then measured by calculating the area corresponding to the portion where the adhesion was released and removed by the tape.

[0039] Generally, as the solid content / viscosity of a polyamic acid composition increases, the adhesion of the polyimide after curing also increases. In other words, there was a problem where the adhesion decreased along with the decrease in solid content or viscosity; however, the polyamic acid composition of the present invention can achieve excellent adhesion to the substrate after curing, even though the solid content and viscosity have been lowered.

[0040] The above polyamic acid composition may be for coating or impregnating a substrate, and specifically, may include all forms in which the polyamic acid composition is coated, adhered, applied, or impregnated onto a substrate.

[0041] The above substrate may be one or more selected from the group consisting of SUS (Stainless Use Steel) substrates, glass substrates, ceramic substrates, and silicon substrates.

[0042] In addition, the present invention comprises the steps of: (a) preparing a composition comprising a polyamic acid having dianhydride and a diamine as polymerization units; and a first solvent; and (b) adding a second solvent to the composition to prepare a diluted polyamic acid composition; wherein, based on a total content of 100 mol% of the dianhydride, the composition comprises 82 to 100 mol% of pyromellitic dianhydride (PMDA), and the diamine comprises 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP), and the composition comprises a temperature of 30°C and 1s -1 A method for preparing a polyamic acid composition is provided, wherein the viscosity of the diluted polyamic acid composition measured at a shear rate is 150 cP or less, and the solid content of the diluted polyamic acid composition is less than 8 wt%.

[0043] The content (composition ratio), viscosity, solid content, etc. of the polyamic acid, solvent, dianhydride, diamine, and monomer in the method for preparing the polyamic acid composition is as described above in the polyamic acid composition of the present invention.

[0044] The first solvent and the second solvent may be the same or different from each other, the first solvent may be a reaction solvent, and the second solvent may be a dilution solvent.

[0045] Specifically, the first solvent and the second solvent may each independently comprise one or more selected from the group consisting of N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), N,N'-dimethylpropanamide (DMPA), N,N-diethylacetamide (DEAc), dimethyl sulfoxide (DMSO), 3-methoxy-N,N-dimethylpropanamide, p-chlorophenol, o-chlorophenol, gamma-butyrolactone (GBL), diglyme, and naphthalene.

[0046] In addition, the present invention provides a polyimide prepared by imidizing the polyamic acid composition.

[0047] In addition, the present invention provides a polyimide comprising a cured product of the polyamic acid composition. Specifically, the cured product of the polyamic acid composition may have an adhesion strength of 4B or higher according to ASTM D 3359. Specifically, when measuring adhesion strength on a substrate according to ASTM D 3359, the removed area of ​​the cured product of the polyamic acid composition may be less than 5% of the total. Here, the substrate may be one or more selected from the group consisting of a SUS (Stainless Steel) substrate, a glass substrate, a ceramic substrate, and a silicon substrate.

[0048] The above polyimide may be in the form of a film, hollow fiber membrane, powder, particle, fiber, etc., but is not limited thereto.

[0049] In addition, the present invention provides a method for manufacturing a polyimide comprising a method for manufacturing a polyamic acid composition.

[0050] The method for manufacturing the above polyimide may include: (a) a step of preparing a composition comprising a polyamic acid having dianhydride and diamine as polymerization units; and a first solvent; and (b) a step of preparing a diluted polyamic acid composition by adding a second solvent to the composition; and (c) a step of preparing a polyimide by an imidation reaction of the diluted polyamic acid composition.

[0051] Specifically, in the method for manufacturing polyimide, polyimide can be produced by thermal imidation and chemical imidation. The thermal imidation method is a method that induces an imidation reaction using a heat source, such as hot air or an infrared dryer, while excluding chemical catalysts. In addition, in the case of chemical imidation, polyimide can be produced using a dehydrating agent and an imidizing agent according to methods known in the art.

[0052] The polyamic acid composition and the method for preparing the same according to the present invention use monomers having an optimal combination and content, and by realizing low viscosity and low solid content, it has the effect of simultaneously securing adhesive strength and mechanical properties.

[0053] In addition, the polyamic acid composition and the method for manufacturing the same according to the present invention have the effect of being usable as a coating material for coating a substrate.

[0054] Examples are provided to aid in understanding the present invention. The following examples are provided merely to facilitate a better understanding of the invention, and the scope of the invention is not limited by these examples.

[0055] [Example]

[0056] Preparation Example 1: Polyamic acid composition containing PMDA and BAPP

[0057] A solvent dimethylacetamide (DMAc) was introduced into a reaction vessel purged with nitrogen gas, 100 mol% of 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) and 100 mol% of pyromellitic dianhydride (PMDA) were introduced, and the mixture was stirred and polymerized at 25°C for 16 hours to prepare a composition (solid content 25 wt%, viscosity at 30°C 6,370 cP, weight-average molecular weight 172,566 g / mol).

[0058] Preparation Example 2: Polyamic acid composition containing PMDA, BAPP, and ODA

[0059] Dimethylacetamide (DMAc) was added as a solvent to a reaction vessel purged with nitrogen gas, 50 mol% of 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP), 50 mol% of 4,4'-diaminodiphenyl ether (ODA), and 100 mol% of pyromellitic dianhydride (PMDA) were added, and the mixture was stirred and polymerized at 25°C for 16 hours to prepare a composition (solid content 25 wt%, viscosity at 30°C 7,460 cP, weight-average molecular weight 139,314 g / mol).

[0060] Preparation Example 3: Polyamic acid composition containing PMDA, BTDA, and BAPP

[0061] A solvent dimethylacetamide (DMAc) was introduced into a reaction vessel purged with nitrogen gas, 100 mol% of 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP), 85 mol% of pyromellitic dianhydride (PMDA), and 15 mol% of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) were introduced, and the mixture was stirred and polymerized at 25°C for 16 hours to prepare a composition (solid content 25 wt%, viscosity at 30°C 7,120 cP, weight-average molecular weight 122,693 g / mol).

[0062] Example: Diluted polyamic acid composition

[0063] Example 1

[0064] DMAc solvent was additionally added to the composition according to Preparation Example 1 to dilute the composition, and finally, a polyamic acid composition was prepared (diluted solid content 5 wt%, viscosity 40 cP at 30°C).

[0065] Example 2

[0066] DMAc solvent was additionally added to the composition according to Preparation Example 2 to dilute the composition, and finally, a polyamic acid composition was prepared (diluted solid content 5 wt%, viscosity 50 cP at 30°C).

[0067] Example 3

[0068] DMAc solvent was additionally added to the composition according to Preparation Example 3 to dilute the composition, and finally, a polyamic acid composition was prepared (diluted solid content 5 wt%, viscosity 50 cP at 30°C).

[0069] Comparative Example 1

[0070] A solvent dimethylacetamide (DMAc) was introduced into a reaction vessel purged with nitrogen gas, 100 mol% of 4,4'-diaminodiphenyl ether (ODA) and 100 mol% of pyromellitic dianhydride (PMDA) were introduced, and the mixture was stirred and polymerized at 25°C for 16 hours to prepare a composition (solid content 25 wt%, viscosity at 30°C 6,790 cP, weight-average molecular weight 38,645 g / mol).

[0071] Next, DMAc solvent was additionally added to the above composition to dilute the composition, and finally, a polyamic acid composition was prepared (diluted solid content 5 wt%, viscosity 20 cP at 30°C).

[0072] Comparative Example 2

[0073] Dimethylacetamide (DMAc) was added as a solvent to a reaction vessel purged with nitrogen gas, 100 mol% of 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) and 82 mol% of pyromellitic dianhydride (PMDA) were added, and the mixture was stirred and polymerized at 25°C for 16 hours to prepare a composition (solid content 25 wt%, viscosity at 30°C 10 cP, weight-average molecular weight 2,740 g / mol). Since the viscosity of the composition itself is very low, it was used as is without dilution.

[0074] Table 1 below lists the monomer composition and content, solid content (solid content before dilution), diluted solid content (solid content after dilution), and viscosity of the diluted polyamic acid compositions according to Examples 1 to 3 and Comparative Example 1, and the polyamic acid composition before dilution of Comparative Example 2. Here, viscosity is measured at a temperature of 30°C and 1s -1 It was measured under shear rate conditions, and the molecular weight was measured as weight-average molecular weight by GPC (Gel Permeation Chromatography) in NMP solvent.

[0075] Classification Monomer (Molar%) Before Dilution After Dilution Dihydrogen Monomer Diamine Monomer Molecular Weight (Mw) (g / mol) Solids (wt%) Viscosity (cP) Diluted Solids (wt%) Viscosity (cP) PM D B T D A B P P D A Example 1 100-100-172,566 256,370 540 Example 2 100-50 50139,314 257,460 550 Example 3 8515 100-122,693 257,120 550 Comparative Example 1 100--100 38,645 256,790 520 Comparative Example 2 82-100-2,740 2510--

[0076] The abbreviations in Table 1 above are defined as follows.

[0077] PMDA: Pyromelittic dianhydride

[0078] BTDA: 3,3',4,4'-BenzophenoneTetracarboxylic Dianhydride

[0079] BAPP: 2,2'-Bis(4-aminophenoxyphenyl)propane

[0080] ODA: 4,4'-Diaminodiphenyl ether

[0081] [Experimental Example]

[0082] Experimental Example 1. Adhesion Evaluation (Crosscut Test)

[0083] Adhesion strength was measured for polyimide films prepared by curing the diluted polyamic acid compositions according to Examples 1 to 3 and Comparative Example 1 and the undiluted polyamic acid composition of Comparative Example 2 using the method presented in ASTM D3359, and the results are shown in Table 2 below. Specifically, regarding the polyimide film prepared by curing the polyamic acid composition according to the examples and comparative examples on a SUS (Stainless Use Steel) substrate, approximately 100 pieces were cut into a checkerboard pattern (1 mm interval) using a cutter, and then a peel test was performed using a dedicated tape, and the degree of peeling was recorded (5B: removed area 0% of the total; 4B: removed area greater than 0% to less than 5% of the total; 3B: removed area 5% or more to less than 15%; 2B: removed area 15% or more to less than 35%; 1B: removed area 35% or more to less than 65%; 0B: removed area 65% or more).

[0084] Classification Dilution Solids (wt%) Viscosity (cP) Adhesion to SUS (Cross-cut) Example 15 40 5B Example 3 5 50 4B Comparative Example 15 200 B Comparative Example 2 2 5 10 Film Manufacturing X

[0085] According to Table 2, Examples 1 and 3 of the present invention achieve low solid content (less than 8 wt%) and low viscosity (150 cP or less), while simultaneously showing excellent adhesion to SUS (Stainless Steel) substrates with an adhesion strength of 4B or higher. Meanwhile, Comparative Example 1, which achieves low solid content (5 wt%) and low viscosity (20 cP) but is not a combination of the present invention, showed an adhesion strength of 0B to a SUS (Stainless Steel) substrate, and Comparative Example 2, which achieves high solid content (25 wt%) and low viscosity (10 cP), had a molecular weight that was too low to manufacture a polyimide film, and the adhesion strength could not even be verified.

[0086] Therefore, the present invention can simultaneously secure adhesive strength and mechanical properties by achieving low viscosity and low solid content through an optimal combination and content of monomers. In particular, even when the solid content and viscosity are lowered within the same monomer combination, mechanical properties (e.g., elongation) are not degraded but maintained at an appropriate level; consequently, the present invention can simultaneously secure mechanical properties such as elongation and adhesive strength. In other words, the present invention is a composition capable of satisfying both adhesive strength and mechanical properties even under low viscosity conditions, and thus has the effect of being utilized as a coating material for coating various substrates.

[0087] The specification omits detailed descriptions of matters that can be sufficiently recognized and inferred by those skilled in the art of the present invention, and various modifications are possible within the scope of not altering the technical concept or essential configurations of the present invention, in addition to the specific examples described in this specification. Accordingly, the present invention may be implemented in a manner different from that specifically described and exemplified in this specification, and this is a matter that can be understood by those skilled in the art.

Claims

1. A polyamic acid composition comprising a polyamic acid having dianhydride and a diamine as polymerization units; and a solvent; wherein Based on a total content of 100 mol% of the above dianhydride, it comprises 82 to 100 mol% of pyromellitic dianhydride (PMDA), and The above diamine comprises 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP), and 30℃ temperature and 1s -1 The viscosity of the polyamic acid composition measured at a shear rate is 150 cP or less, and A polyamic acid composition having a solid content of less than 8 wt%.

2. In Paragraph 1, A polyamic acid composition comprising 0 to 18 mol% of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) based on 100 mol% of the total content of the dianhydride.

3. In Paragraph 1, A polyamic acid composition having a solid content of 1 wt% or more and less than 8 wt%.

4. In Paragraph 1, A polyamic acid composition comprising one or more solvents selected from the group consisting of N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), N,N'-dimethylpropanamide (DMPA), N,N-diethylacetamide (DEAc), dimethyl sulfoxide (DMSO), 3-methoxy-N,N-dimethylpropanamide, p-chlorophenol, o-chlorophenol, gamma-butyrolactone (GBL), Diglyme, and naphthalene.

5. In Paragraph 1, A polyamic acid composition having a weight-average molecular weight (Mw) of 100,000 to 200,000 g / mol of the polyamic acid.

6. The polyamic acid composition according to claim 1, wherein after curing the polyamic acid composition, the adhesion strength according to ASTM D 3359 is 4B or higher.

7. In Paragraph 1, The above polyamic acid composition is a polyamic acid composition intended for coating a substrate.

8. In Paragraph 7, A polyamic acid composition wherein the substrate is one or more selected from the group consisting of a SUS (Stainless Use Steel) substrate, a glass substrate, a ceramic substrate, and a silicon substrate.

9. In Paragraph 1, A polyamic acid composition wherein the above polyamic acid comprises pyromellitic dianhydride (PMDA) and 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) as polymerization units, or comprises pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP) as polymerization units.

10. (a) a step of preparing a composition comprising a polyamic acid having dianhydride and a diamine as polymerization units; and a first solvent; and (b) a step of preparing a diluted polyamic acid composition by adding a second solvent to the above composition; comprising, Based on a total content of 100 mol% of the above dianhydride, it comprises 82 to 100 mol% of pyromellitic dianhydride (PMDA), and The above diamine comprises 2,2'-bis(4-aminophenoxyphenyl)propane (BAPP), and 30℃ temperature and 1s -1 The viscosity of the diluted polyamic acid composition measured at the shear rate is 150 cP or less, and A method for preparing a polyamic acid composition in which the solid content of the diluted polyamic acid composition is less than 8 wt%.

11. In Paragraph 10, A method for preparing a polyamic acid composition, wherein the first solvent and the second solvent may be the same or different from each other and each independently comprise one or more selected from the group consisting of N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), N,N'-dimethylpropanamide (DMPA), N,N-diethylacetamide (DEAc), dimethyl sulfoxide (DMSO), 3-methoxy-N,N-dimethylpropanamide, p-chlorophenol, o-chlorophenol, gamma-butyrolactone (GBL), Diglyme, and naphthalene.

12. A polyimide comprising a cured product of a polyamic acid composition according to any one of claims 1 to 9.

13. In paragraph 12, the cured product of the polyamic acid composition is a polyimide having an adhesion strength of 4B or higher according to ASTM D 3359.

14. In paragraph 12, the cured polyamic acid composition is a polyimide in which the removed area is less than 5% of the total when measuring adhesion strength on a substrate according to ASTM D 3359.