Polyimide compound containing side chain and method for producing same

Abstract

According to the present disclosure, a polyimide compound is provided, wherein the polyimide compound comprises: a main chain having a monomer comprising an imide functional group; and one or more side chains of Formula 1 bonded to the main chain. Herein, R is an alkyl group having 1 to 30 carbon atoms, and X represents O, S, or NH. The polyimide compound has the advantage of excellent dielectric properties and excellent solubility in organic solvents.

Description

Technology Field

[0001] The present disclosure relates to a polyimide-based compound containing a side chain and a method for manufacturing the same. Background Technology

[0002] Recently, active research and development have been underway regarding substrate materials applicable to ultra-high-speed communication electronic components in the high-frequency range. To achieve high-speed signal processing while minimizing communication signal delay, substrate materials with low dielectric constants, excellent low dielectric loss characteristics, and superior heat resistance are required. Substrate materials are primarily fabricated using compositions containing thermosetting polymers; among various polymer materials, polyimide is attracting attention as a substrate material for ultra-high-speed communication and for the construction of redistribution layers (RDLs) due to its excellent dielectric properties and heat resistance.

[0003] It is known that the dielectric constant of a polymer matrix decreases as the free volume between polymer chains increases. To lower the dielectric constant of polyimide, a technique has been proposed to increase the free volume by introducing a bulky chemical structure into the internal chemical structure of polyimide. The problem to be solved

[0004] The present disclosure aims to provide a polyimide polymer compound with excellent dielectric properties in which an isocyanate compound is bonded as a side chain. means of solving the problem

[0005] According to a first aspect of the present disclosure, a polyimide compound is provided, said polyimide compound comprises: a main chain having a monomer comprising an imide functional group; and one or more side chains of Formula 1 bonded to said main chain.

[0006]

[0007] Here, R is an alkyl group having 1 to 30 carbon atoms, and X represents O, S, or NH.

[0008] In one embodiment, the main chain may include a monomer of Formula 2.

[0009]

[0010] In one embodiment, the polyimide compound may include 1 to 50 side chains.

[0011] In one embodiment, the polyimide compound has a weight average molecular weight (M) of 10,000 to 20,000. w Can have ).

[0012] According to a second aspect of the present disclosure, a method for preparing a polyimide compound is provided, said method comprising: providing a polyamic acid; converting the polyamic acid into a polyimide; and reacting the polyimide with an isocyanate compound to bond the isocyanate compound to the polyimide.

[0013] In one embodiment, the step of bonding an isocyanate compound to the polyimide can be performed at a temperature of 50 to 200°C without a catalyst.

[0014] In one embodiment, the isocyanate compound may include an alkyl group having 1 to 30 carbon atoms.

[0015] In one embodiment, the step of bonding an isocyanate compound to the polyimide can be performed for 20 to 60 minutes.

[0016] In one embodiment, the molar ratio of the isocyanate compound reacted to the polyimide in the step of bonding the isocyanate compound to the polyimide may be 1 to 50.

[0017] According to a third aspect of the present disclosure, a polyimide film is provided, said polyimide film comprises: the aforementioned polyimide compound; a reactive diluent; and a photoinitiator.

[0018] In one embodiment, the polyimide film can be photocured and heat-cured. Effects of the invention

[0019] According to the present disclosure, a polyimide compound having excellent dielectric properties and excellent solubility in organic solvents can be obtained through a simplified process. Brief explanation of the drawing

[0020] Figure 1 is a schematic diagram of the steps for manufacturing polyamic acid according to one embodiment. FIG. 2 is a schematic diagram of the conversion step of polyamic acid to polyimide (PI) according to one embodiment. FIG. 3 is a schematic diagram of the bonding step of an isocyanate compound to a polyimide according to one embodiment. Figures 4 to 6 are nuclear magnetic resonance (H-NMR) peak data for a polyimide-based compound according to one embodiment. Specific details for implementing the invention

[0021] Hereinafter, the present disclosure will be described in detail with reference to the attached drawings. However, this is merely illustrative and the present disclosure is not limited to the specific embodiments described illustratively.

[0022] Polyimide compounds

[0023] A polyimide compound according to the first aspect of the present disclosure comprises: a main chain having a monomer comprising an imide functional group; and one or more side chains of Formula 1 bonded to the main chain.

[0024]

[0025] Here, R is an alkyl group having 1 to 30 carbon atoms, and X represents O, S, or NH.

[0026] A main chain having a monomer containing an imide functional group refers to a long chain formed by the polymerization of a monomer containing an imide functional group. The main chain is a polyimide that imparts dielectric properties and heat resistance to polyimide-based compounds. The main chain may be a saturated hydrocarbon polyimide or an unsaturated hydrocarbon polyimide. A saturated hydrocarbon polyimide refers to a polyamide in which unsaturated hydrocarbons are not present in the monomer, and an unsaturated hydrocarbon polyimide refers to a polyimide in which unsaturated hydrocarbons are present in the monomer. In particular, when the main chain is an aromatic polyimide among unsaturated hydrocarbon polyimides, a carboxylic acid anhydride group present in the polyimide functional group may act as an electron acceptor, and an amine group bonded to an aromatic ring may act as an electron donor to form a charge transfer complex (CTC). This can contribute to the optical stability of the main chain.

[0027] In one embodiment, the main chain may include a monomer of Formula 2.

[0028]

[0029] The main chain formed by the polymerization of the above monomer corresponds to an aromatic polyimide. The above monomer facilitates the bonding of a side chain at a corresponding position by having the oxygen atom of the phenyl group bonded to the nitrogen of the imide functional group act as an electron donor, thereby improving the heat resistance of the polyimide-based compound containing it.

[0030] The side chain of Chemical Formula 1 bonded to the main chain is formed by bonding a carbon portion of an isocyanate group with a chemical structure like Chemical Formula 3 to a part of the main chain.

[0031]

[0032] Specifically, the side chain is formed when a carbon atom forming double bonds with the nitrogen and oxygen of Chemical Formula 3 receives electrons from an electron pair donor present in the main chain to form a bond. The side chain provides a steric effect to the polyimide compound. The steric effect refers to an increase in free volume due to the gap between each polyimide chain caused by the protrusion of the side chain when multiple polyimide chains are stacked. As the free volume increases, the dielectric constant of the polyimide resin containing it is lowered, and consequently, the insulation properties of the polyimide resin can be improved. Additionally, the side chain exhibits polarity, which can provide the advantage of strong adhesion to the substrate when the polyimide compound is deposited on a metal substrate.

[0033] In one embodiment, the polyimide-based compound may include 1 to 50 side chains. If the polyimide-based compound includes fewer than 1 side chain, the aforementioned steric effect does not occur, and the insulating properties of the polyimide resin containing the polyimide-based compound may not be improved. If the polyimide-based compound includes more than 50 side chains, the degree to which the side chains inhibit the bonding between each polyimide chain is higher than the degree to which they increase the free volume between the polyimide chains, which may lower the chemical stability of the polyimide resin containing it and also lower the insulating properties of the polyimide resin. In one embodiment, the polyimide-based compound may specifically include 10 to 40 side chains, more specifically 10 to 30 side chains.

[0034] In one embodiment, the polyimide-based compound has a weight average molecular weight (M) of 10,000 to 20,000. wIt may have ). The weight-average molecular weight of a polymer, such as a polyimide-based compound, is one of the factors that can be used to infer the average length of the polymer chain and the average number of side chains. If the polyimide-based compound has a weight-average molecular weight of less than 10,000, the Van Der Waals force, which is a factor affecting the bonding strength between each polyimide chain, is small, which may reduce the chemical stability and insulation properties of the resin containing the polyimide-based compound. If the polyimide-based compound has a weight-average molecular weight of more than 20,000, this means that the main chain of the polyimide-based compound contains not only an excess of monomers but also an excess of side chains. In this case, the degree to which the bonding between each polyimide chain is inhibited is higher than the degree to which the free volume between polyimide chains is increased, which may reduce the chemical stability of the polyimide resin containing it and also reduce the insulation properties of the polyimide resin. In one embodiment, the polyimide-based compound may specifically have a weight average molecular weight of 10,000 to 15,000, more specifically 12,000 to 14,000.

[0035] According to a second aspect of the present disclosure, a method for preparing a polyimide-based compound is provided, the method comprising: providing a polyamic acid; converting the polyamic acid into a polyimide; and reacting the polyimide with an isocyanate compound to bond the isocyanate compound to the polyimide.

[0036] The step of providing polyamic acid can be performed by any combination of compounds. For example, the step of providing polyamic acid can be performed by a chemical reaction as shown in FIG. 1. Polyamic acid can be formed by reacting 6FDA (4,4'-(Hexafluoroisopropylidene)diphthalic anhydride), 6FOHA (2,2-bis(3-amino-4-hydroxyphenyl)hexafluropropane), SiDA (1,3-bis(3-aminopropyl)tetramethyldisiloxane), and MA (maleic anhydride) under NMP (N-methyl-2-pyrrolidone) solvent and a nitrogen atmosphere at 0 °C for 4 hours, then at 60 °C for 2 hours, and then at 110 °C for 2 hours.

[0037] After the polyamic acid providing step, a step of converting the polyamic acid into polyimide is performed. The conversion step may correspond to a condensation reaction. For example, as shown in FIG. 2, when the polyamic acid produced in the polyamic acid providing step is heat-treated at 205 °C for 4 hours, the carboxylic acid at the end of the polyamic acid reacts with the nitrogen of a urethane-like functional group conjugated thereto, and through a condensation reaction, a water molecule of the carboxylic acid is released, forming a terminal ring. The polymer obtained through the above reaction corresponds to polyimide.

[0038] In addition to the above method, if polyamic acid and polyimide can be formed, the polyamic acid providing step and the polyimide conversion step can be performed through any method.

[0039] The step of reacting a polyimide with an isocyanate compound to bond the isocyanate compound to the polyimide is performed by adding the polyimide and the isocyanate compound to a tetrahydrofuran (THF) solvent and heating for a predetermined time after the polyimide is formed. For example, as shown in FIG. 3, when the isocyanate compound is hexyl isocyanate, the polyimide and hexyl isocyanate can be added to a THF solvent and heated at a temperature of 100°C or higher for a predetermined time to bond the hexyl isocyanate as a side chain to the electron pair donor sites of the polyimide main chain. Conventionally, to improve the free volume of polyimide-based compounds, polymerization was attempted by selecting a bulky monomer during the polymerization step; however, in this case, not only was there difficulty in selecting the monomer, but there was also difficulty in controlling the molecular weight of the polymer chain due to the large molecular weight of the monomer itself. In contrast, the present manufacturing method has the advantage of improving the free volume of polyimide compounds and facilitating molecular weight control through a simple process of forming a polyimide main chain and then grafting an isocyanate compound as a side chain.

[0040] In one embodiment, the step of attaching an isocyanate compound to the polyimide can be performed without a catalyst at a temperature of 50 to 200 °C. As described above, the process of grafting a side chain onto the main chain of a polymer is typically performed in the presence of a catalyst, but the present invention has the advantage of being able to perform grafting without a catalyst. At this time, if the step of attaching an isocyanate compound to the polyimide is performed at a temperature below 50 °C, the activation energy required for side chain grafting is not supplied, so the isocyanate compound may not be attached to the main chain as a side chain; and if the step is performed at a temperature above 200 °C, the isocyanate functional group may be damaged by heat, which may reduce the side chain graft yield. In one embodiment, the step of attaching an isocyanate compound to the polyimide can be performed without a catalyst at a temperature of specifically 100 to 150 °C, more specifically 120 to 130 °C.

[0041] In one embodiment, the isocyanate compound may include an alkyl group having 1 to 30 carbon atoms. If the isocyanate compound does not include an alkyl group, the steric effect due to the presence of the alkyl group may not be expressed, and if the isocyanate compound includes an alkyl group having more than 30 carbon atoms, steric hindrance that inhibits bonding between polyimide chains may occur due to the size of the side chain, and the stability of the polyimide resin containing it may be reduced.

[0042] In one embodiment, the step of bonding an isocyanate compound to the polyimide may be performed for 20 to 60 minutes. The reaction time of the step of bonding an isocyanate compound to the polyimide may affect the number of side chains grafted onto the main chain, the polyimide. If the step of bonding an isocyanate compound to the polyimide is performed for less than 20 minutes, there may not be enough time for the reaction between the polyimide and the isocyanate compound to graft side chains. If the step is performed for more than 60 minutes, an excess of side chains, for example, more than 50, may be grafted, which may reduce the chemical stability of the polyimide resin containing it and also reduce the insulating properties of the polyimide resin. In one embodiment, the step of bonding an isocyanate compound to the polyimide may be performed specifically for 20 to 50 minutes, more specifically for 30 to 40 minutes.

[0043] In one embodiment, the molar ratio of the isocyanate compound reacted to the polyimide in the step of bonding the isocyanate compound to the polyimide may be 1 to 50. If the molar ratio is less than 1, the isocyanate compound may not be bonded as a side chain, and if the molar ratio is greater than 50, an excess amount of the isocyanate compound may be bonded as a side chain, which may cause steric hindrance. In one embodiment, the molar ratio of the isocyanate compound reacted to the polyimide in the step of bonding the isocyanate compound to the polyimide may be specifically 5 to 40, more specifically 10 to 30.

[0044] According to a third aspect of the present disclosure, a polyimide film is provided, which comprises: a polyimide compound according to the first aspect; a reactive diluent; and a photoinitiator.

[0045] The polyimide film is formed by molding a resin containing the aforementioned polyimide compound into a thin film, and in addition to the polyimide compound, it may include a reactive diluent for controlling the viscosity of the resin and a curing initiator for curing the resin. There are no limitations on the curing method of the film.

[0046] In one embodiment, the polyimide film may be photocured and heat-cured. As previously mentioned, since there are no restrictions on the curing method of the polyimide film, the polyimide film may be photocured or heat-cured. Additionally, the polyimide film may be heat-cured after photocuring or photocured after heat-curing. It has been experimentally confirmed that when cured by both curing methods, the dielectric constant and dielectric loss characteristics of the polyimide film are improved. That is, the polyimide film according to one embodiment can exhibit excellent dielectric properties by being photocured and heat-cured.

[0047] Preferred embodiments are provided below to aid in understanding the present disclosure, but the following embodiments are provided only to facilitate a better understanding of the present invention and are not intended to limit the present disclosure.

[0048] Preparation Example

[0049] As shown in Fig. 1, polyamic acid was synthesized by adding 6FOHA, SiDA, 6FDA, and MA to an NMP solvent and reacting at 0 °C for 4 hours, 60 °C for 2 hours, and 110 °C for 2 hours. Subsequently, as shown in Fig. 2, the polyamic acid was reacted at 205 °C for 2 hours to condense water, and then washed with a mixed solution of deionized water and methanol to obtain a solid polyimide (PI). Subsequently, as shown in Fig. 3, the obtained polyimide was added to a THF solvent together with hexyl isocyanate and reacted at a temperature of 130 °C to obtain a polyimide-based compound having polyimide as the main chain and hexyl isocyanate as the side chain. The reaction between the polyimide and the hexyl isocyanate was carried out for 30 to 60 minutes, and the polyimide compounds obtained as a result had 2, 5, 10, 15, and 30 side chains. Hereinafter, the polyimide compound with 2 side chains will be referred to as PI-H2, and the polyimide compound with 10 side chains will be referred to as PI-H10.

[0050] Experimental Example 1 - Measurement of the molecular weight of a polyimide compound

[0051] Peak molecular weight (M) of a polyimide-based compound having a different number of side chains in the preparation example p ), number average molecular weight (M n ) and weight-average molecular weight (M w ) was measured using the Gel Permeation Chromatography (GPC) method. For the GPC measurement, polystyrene was used as the stationary phase and standard material. The measurement results are shown in Table 1.

[0052]

[0053] Referring to Table 1, it was confirmed that the number-average molecular weight and weight-average molecular weight of polyimide compounds increased linearly as the number of side chains derived from hexyl isocyanate increased, and M nand M w It was confirmed that the polydisperse index (PDI), corresponding to the ratio, also increased linearly. Considering that polymers with high molecular weights generally exhibit high free volumes, it can be inferred that the number of hexyl isocyanate side chains in polyimide compounds is linearly proportional to their free volume.

[0054] Experimental Example 2 - Measurement of H-NMR (nuclear magnetic resonance) of polyimide-based compounds

[0055] Among the polyimide compounds of the preparation examples having different numbers of side chains, one without side chains (PI), one with 10 side chains (PI-H10), and one with 30 side chains (PI-H30) were irradiated with electromagnetic waves having a frequency of 300 MHz using a nuclear magnetic resonance spectrometer. The results were as shown in FIGS. 4 to 6, respectively.

[0056] In FIGS. 4 to 6, a peak corresponding to the hexyl group of hexyl isocyanate was observed at a δ value of approximately 1.2, and the size of the peak was observed to increase in proportion to the increase in the number of side chains. From this, it was confirmed that, according to the above preparation example, hexyl isocyanate can be bonded to the main chain of polyimide as a side chain by a simple process of adding polyimide and hexyl isocyanate to a THF solvent and reacting them at a temperature of 130 °C.

[0057] Experimental Example 3 - Evaluation of Solubility of Polyimide Compounds in Organic Solvents

[0058] Polyimide compounds having different numbers of side chains from the preparation examples were added to acetone, NMP, THF, toluene, DMSO (dimethyl sulfoxide), and CHCl3 organic solvents to evaluate their solubility. Each polyimide compound was added to an organic solvent at room temperature, and if it did not dissolve at room temperature, the solvent was gradually heated to determine the point of dissolution. The measurement results are shown in Table 2.

[0059]

[0060] Referring to Table 2, it can be seen that polyimide compounds containing different numbers of side chains exhibit the same level of solubility in organic solvents as polyimide compounds without side chains. From this, it can be inferred that attaching alkyl isocyanate side chains to polyimide does not reduce the solubility of polyimide compounds.

[0061] Experimental Example 4 - Measurement of Dielectric Properties of Polyimide Film

[0062] A resin comprising the polyimide-based compound of the preparation example, a reactive diluent, and the photoinitiator Igracure 819 was prepared and tape-cast to a thickness of 10 μm. Subsequently, thin films were obtained by photocuring the tape-cast resin by exposing it to light at wavelengths of 365 nm and 405 nm for 3 minutes. Additionally, for the same resin, additional thin films were obtained by applying different curing methods—photocuring and thermal curing—to each. The photocuring process conditions were the same as above, and thermal curing was performed by heat-treating the resin at 200 °C for 1 hour. Cobalt(II) oxalate dihydrate was used as the catalyst for thermal curing. The dielectric constant (Dk) and dielectric loss (Df) of these thin films were measured using an SCR (Split Cylinder Resonator) instrument under the IPC-TM-6 50 2.5.5.13 standard, and the measurement results are shown in Table 3.

[0063]

[0064] Referring to Table 3, it can be seen that thin films cured by the same curing method exhibit excellent dielectric properties as the number of hexyl isocyanate side chains increases, which is presumed to be a result of the increase in free volume between polymer chains as the number of side chains increases.

[0065] Meanwhile, it was confirmed that thin films cured by photocuring and thermal curing exhibit superior dielectric properties compared to thin films cured by photocuring. This is inferred to be due to the reduction in the proportion of unreacted cured functional groups (e.g., maleimide and acrylate) present after the photocuring process by additionally proceeding with the thermal curing process after the photocuring process.

[0066] The present disclosure has been described in detail through specific embodiments. The embodiments are intended to specifically explain the present disclosure and are not limited thereto. It will be apparent that modifications or improvements can be made by those skilled in the art within the technical scope of the present disclosure.

[0067] All simple variations or modifications of the present disclosure fall within the scope of the present disclosure, and the specific scope of protection of the present disclosure will be clarified by the appended claims.

Claims

Claim 1 A polyimide compound comprising: a main chain having a monomer containing an imide functional group; and one or more side chains of Formula 1 bonded to the main chain. Here, R is an alkyl group having 1 to 30 carbon atoms, and X represents O, S, or NH. Claim 2 A polyimide compound according to claim 1, wherein the main chain comprises a monomer of formula 2. Claim 3 The polyimide compound of claim 1, wherein the polyimide compound comprises 1 to 50 side chains. Claim 4 In claim 1, the polyimide-based compound has a weight average molecular weight (M) of 10,000 to 20,000. w A polyimide compound having ). Claim 5 A method for manufacturing a polyimide-based compound according to claim 1, comprising: a step of providing a polyamic acid; a step of converting the polyamic acid into a polyimide; and a step of reacting the polyimide with an isocyanate compound to bond the isocyanate compound to the polyimide. Claim 6 A method for producing a polyimide-based compound according to claim 5, wherein the step of bonding an isocyanate compound to a polyimide is performed at a temperature of 50 to 200 ℃ without a catalyst. Claim 7 A method for preparing a polyimide-based compound according to claim 5, wherein the isocyanate compound comprises an alkyl group having 1 to 30 carbon atoms. Claim 8 A method for manufacturing a polyimide-based compound according to claim 5, wherein the step of bonding an isocyanate compound to a polyimide is performed for 20 to 60 minutes. Claim 9 A method for manufacturing a polyimide-based compound according to claim 5, wherein the molar ratio of the isocyanate compound reacted to the polyimide in the step of bonding the isocyanate compound to the polyimide is 1 to 50. Claim 10 As a polyimide film: a polyimide compound of claim 1; a reactive diluent; and a photoinitiator, the polyimide film. Claim 11 In claim 10, the polyimide film is a photocured and heat-cured polyimide film.

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