阅读说明：本技术 一种聚酰亚胺复合物材料、其制备方法及其应用 (Polyimide composite material, preparation method and application thereof ) 是由 汪亚民 于 2019-09-27 设计创作，主要内容包括：本发明提供了一种聚酰亚胺复合物材料、其制备方法及其应用。其中所述聚酰亚胺复合物材料将纳米无机粒子引入到前驱体聚酰胺酸中,通过两者间的化学反应而非常见的一般掺杂方式形成一种新型的纳米无机粒子补强型聚酰亚胺复合物材料,从而有效提高其自身材料的机械性能和热稳定性。(The invention provides a polyimide composite material, a preparation method and application thereof. The polyimide composite material introduces nano inorganic particles into precursor polyamic acid, and forms a novel nano inorganic particle reinforced polyimide composite material through a chemical reaction between the nano inorganic particles and the precursor polyamic acid instead of a common doping mode, so that the mechanical property and the thermal stability of the material are effectively improved.)

1. A polyimide composite material; the composite is characterized in that the adopted molecular structural formula comprises coupled inorganic nanoparticles and polyimide molecules;

the nano inorganic particles are obtained by modifying with a coupling agent, and are connected with the polyimide molecules in a chemical bond mode to form an organic-inorganic interface in a coupled molecular structure of the polyimide molecules and the polyimide molecules.

2. The polyimide composite material of claim 1; the preparation method is characterized in that the inorganic particles selected from the nano inorganic particles comprise one of P2O5, Al2O3, SiO2 and AlN.

3. The polyimide composite material of claim 1; characterized in that the coupling agent used therein comprises a silane coupling agent: n- (. beta. -aminoethyl) -gamma. -aminopropyltriethoxysilane.

4. The polyimide composite material of claim 1; characterized in that the inorganic particle compound selected by the nano inorganic particles is P₂O₅The general molecular structure formula adopted by the compound is as follows:

5. the polyimide composite material of claim 4; the P2O5 in the molecular structure general formula is characterized by adopting the following structure:

6. the polyimide composite material of claim 4; the preparation method is characterized in that the preparation raw materials of the compound comprise polyamic acid and nano inorganic particles modified by a coupling agent; wherein the polyamic acid adopts a structural general formula as follows:

wherein the inorganic nanoparticles after modification treatment adopt a structural general formula as follows:

7. the polyimide composite material of claim 6; the preparation method is characterized in that the polyamide acid adopts preparation raw materials comprising phenylether dianhydride and p-phenylenediamine, and the polyamide acid is prepared by adopting the following synthetic route;

8. a preparation method for preparing the polyimide composite according to claim 1; the method is characterized by comprising the following steps:

step S1 of dissolving a predetermined inorganic particle compound in a coupling agent to form a first mixed solution, and treating the first mixed solution so that the inorganic particles are uniformly dispersed in the coupling agent;

step S2, adding the preparation raw material of the polyamic acid into the first mixed solution to form a second mixed solution, reacting at 50-100 ℃ for 5-12 h, and removing air bubbles in the second mixed solution after the reaction is finished, wherein the reacted second mixed solution contains the polyamic acid; and

step S3, performing a constant temperature process (repeat) on the second mixed solution, so that the polyimide molecular structure formed after the polyamic acid molecules in the second mixed solution are cross-linked and cured and the inorganic nanoparticle structure modified by the coupling agent are coupled together in a chemical bond manner, and an organic-inorganic interface is formed in the molecular structure.

9. The production method according to claim 8; characterized in that, in the step S1, wherein the predetermined inorganic particle compound is a P2O5 particle compound; adding a selected P2O5 particle compound into an alcohol-water solution, then adding 1-3 wt% of a silane coupling agent into the alcohol-water solution to form a first mixed solution, and then treating the first mixed solution to uniformly disperse the P2O5 in the first mixed solution.

10. A PI substrate comprises a substrate and a polyimide film layer arranged on the substrate; the polyimide film layer is characterized in that the selected constituent material of the polyimide film layer comprises the polyimide composite material according to claim 1.

Technical Field

The invention relates to the field of functional materials, in particular to a functional Polyimide (PI) composite material which can be used as a substrate material of various photoelectric devices, such as an OLED display panel, a solar cell panel and the like, but is not limited to.

Background

It is known that more and more new optoelectronic devices such as OLED panels, solar panels, etc. are developing towards flexibility, lightness and thinness.

Among them, the advent of flexible electronics has made it possible to bring about a great revolution in Human-Computer Interaction (HCI). However, before this, there were still a number of technical hurdles to overcome one by one. The flexibility of the device depends to a large extent on the substrate material used. For example, in the OLED field, flexible substrates are one of the two formidable cores known in the industry in parallel with evaporation techniques.

Currently, the material enterprises in the industry are beginning to gradually increase the research and development of PI materials for OLED flexible substrates. With the development of the present invention, it is found that one of the key properties in this application is the mechanical properties of the PI material.

Although different types of PI materials have been developed, the industry has broken through the PI materials that have their own property limits such as permeability and thermal expansion coefficient, these PI materials ultimately have poor mechanical properties due to the inherent defects in the formulation of the raw materials for their preparation. Therefore, although the PI materials meet the requirements on other performance parameters, the PI materials are finally difficult to be used as OLED substrate materials for subsequent large-scale marketing due to the non-compliance of mechanical performance parameters.

Therefore, in summary, the substrate material required by the industry is to have sufficient flexibility and also have a sufficiently rigid main chain structure in its own molecular structure, so that the OLED substrate layer formed by the substrate material can meet the requirements of the industry in terms of tensile property and bending property.

Disclosure of Invention

One aspect of the present invention is to provide a polyimide composite material, wherein nano inorganic particles are introduced into a precursor polyamic acid, and a chemical reaction is performed between the nano inorganic particles and the precursor polyamic acid, instead of a common general doping method, to form a novel nano inorganic particle reinforced polyimide composite material, so as to effectively improve the mechanical properties and thermal stability of the material.

The technical scheme adopted by the invention is as follows:

a polyimide composite material adopts a molecular structural formula which comprises coupled inorganic nanoparticles and polyimide molecules; the nano inorganic particles are obtained by modifying with a coupling agent, and are connected with the polyimide molecules in a chemical bond mode to form an organic-inorganic interface in a coupled molecular structure of the polyimide molecules and the polyimide molecules.

Further, in various embodiments, the inorganic particles selected for the nano inorganic particles include one of P2O5, Al2O3, SiO2, and AlN.

Further, in various embodiments, the coupling agents used therein include silane coupling agents: n- (. beta. -aminoethyl) -gamma. -aminopropyltriethoxysilane, but is not limited thereto.

Further, in various embodiments, the inorganic particle compound selected for the nano inorganic particles is P₂O₅The general molecular structure formula adopted by the compound is as follows:

further, in various embodiments, wherein P is in formula₂O₅The structure is as follows:

further, in various embodiments, the preparation raw material of the composite comprises polyamic acid and nano inorganic particles modified by a coupling agent; wherein the polyamic acid adopts a structural general formula as follows:

wherein the inorganic nanoparticles after modification treatment adopt a structural general formula as follows:

further, in various embodiments, the polyamic acid is prepared from raw materials including phenylether dianhydride and p-phenylenediamine, and the polyamic acid is prepared by the following synthetic route;

further, another aspect of the present invention is to provide a method for preparing the polyimide composite according to the present invention, comprising the steps of:

step S1 of dissolving a predetermined inorganic particle compound in a coupling agent to form a first mixed solution, and treating the first mixed solution so that the inorganic particles are uniformly dispersed in the coupling agent;

step S2, adding the preparation raw material of the polyamic acid into the first mixed solution to form a second mixed solution, reacting at 50-100 ℃ for 5-12 h, and removing air bubbles in the second mixed solution after the reaction is finished, wherein the reacted second mixed solution contains the polyamic acid; and

step S3, performing a constant temperature process (repeat) on the second mixed solution, so that the polyimide molecular structure formed after the polyamic acid molecules in the second mixed solution are cross-linked and cured and the inorganic nanoparticle structure modified by the coupling agent are coupled together in a chemical bond manner, and an organic-inorganic interface is formed in the molecular structure.

Further, in various embodiments, in the step S1, wherein the predetermined inorganic particle compound is a P2O5 particle compound; the method comprises the steps of adding a selected P2O5 particle compound into an alcohol-water solution (such as, but not limited to, 95ml of ethanol and water: 5ml), adding 1-3 wt% of a silane coupling agent into the mixture to form a first mixed solution, and treating the first mixed solution to uniformly disperse the P2O5 in the first mixed solution.

Further, in a different embodiment, in the step S1, the processing of the first mixed solution includes performing ultrasonic processing on the first mixed solution for 1 to 6 hours by using an ultrasonic disperser, and heating the first mixed solution at a water bath temperature of 40 to 70 ℃.

Further, in a different embodiment, in the step S3, the second mixed solution is coated on a substrate, then, the second mixed solution coated on the substrate is subjected to an H-VCD process at a temperature of 110 to 130 ℃ to remove 55 to 75 percent of the solvent in the second mixed solution coated on the substrate, then heating the substrate and performing a constant temperature process (Recipe) with a maximum temperature of 400-500 ℃, and the polyamic acid contained in the second mixed solution coated on the substrate is crosslinked and cured to form polyimide, and simultaneously is connected with the modified inorganic nanoparticles obtained after the modification treatment of the coupling agent in a chemical bond mode to form an organic-inorganic interface in the molecular structure, so that the polyimide composite material related to the invention is finally obtained.

Further, in a different embodiment, in the step S3, the constant temperature process performed on the second mixed solution is about 3 to 5 hours, that is, the cross-linking curing process of the polyamic acid therein lasts for 3 to 5 hours, wherein the temperature rising rate is 4 to 10 ℃/min, and the highest temperature is in the range of 420 to 500 ℃.

Further, another aspect of the present invention is to provide a use of the polyimide composite material according to the present invention, which is used for forming a polyimide film layer disposed on a substrate. The polyimide film layer formed by the polyimide composite can be used for a substrate of an OLED, but is not limited to the substrate.

Compared with the prior art, the invention has the beneficial effects that: the preparation method of the polyimide composite material is different from simple blending between common nano particles and dianhydride/diamine, but introduces a coupling agent to perform grafting reaction with preset nano inorganic particles to form an aggregation mechanism taking reinforced nano inorganic particles as the center, then introduces modified nano inorganic particles obtained after modification treatment of the coupling agent into precursor polyamic acid, connects the modified nano inorganic particles and the precursor polyamic acid in a chemical bond mode through chemical reaction between the modified nano inorganic particles and the precursor polyamic acid, and forms a novel inorganic-organic interface in the molecular structure, thereby obtaining the nano inorganic particle reinforced polyimide composite material which effectively improves the mechanical property and the thermal stability of the material.

Specifically, the coupling agent selected for the inorganic nanoparticles is a silane coupling agent, such as N- (beta-aminoethyl) -gamma-aminopropyl triethoxy silane, commonly known as silane coupling agent KH-791 (KH-791), which can generate a large amount of hydroxyl groups (-OH) due to hydrolysis, and can be subjected to dehydration condensation polymerization with the hydroxyl groups around the inorganic nanoparticles in the solution to form bonds; in addition, the amino group (-NH 2) at the end of KH-791 can react with the carboxyl group (-COOH) of the precursor polyamic acid, so that KH-791 plays a role in grafting, polyimide molecules formed after the nano inorganic particles and the precursor polyamic acid are crosslinked and cured are connected through chemical bonds, and an organic-inorganic interface is formed in the molecular structure, and the agglomeration among the nano inorganic particles is reduced.

The inorganic nanoparticles reinforce the linear chains in the molecular structure, and the added inorganic nanoparticles are not added by a simple doping method, but are connected with polyimide molecules in a coupling mode of chemical bond connection to form an organic-inorganic interface in the molecular structure, so that the mechanical property and the thermal stability of the composite material are improved.

However, it is to be understood that the polyimide composite material according to the present disclosure is not limited to a substrate for an OLED, and may be applied to various suitable applications as long as the performance parameters of a target composite obtained according to different raw material ratios meet requirements.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a PI substrate according to an embodiment of the present invention;

FIG. 2 is a schematic process diagram of a constant temperature process provided in one embodiment of the present invention;

FIG. 3 is a schematic process diagram of a constant temperature process according to another embodiment of the present invention;

FIG. 4 is a schematic process diagram of a constant temperature process according to yet another embodiment of the present invention;

FIG. 5 is a schematic process diagram of a constant temperature process according to yet another embodiment of the present invention;

FIG. 6 is a graph showing the thermal expansion coefficient of a PI film made of the polyimide composite material according to the present invention according to still another embodiment of the present invention; and

fig. 7 is a stress-strain curve diagram of the PI film layer shown in fig. 6 and a film layer made of a conventional polyimide material.

Detailed Description

The polyimide material, the preparation method and the application thereof according to the present invention will be described in further detail with reference to the accompanying drawings and examples.

Wherein, because the present invention relates to a structure of a polyimide composite material and a preparation method thereof, in order to avoid unnecessary repeated description and clearer explanation, the following will mainly describe the structure of the polyimide composite material related to the present invention in detail by taking the preparation method as a main point.

One embodiment of the invention provides a method for preparing the polyimide composite material, which can be summarized as a three-step method:

firstly, preparing modified nano inorganic particles;

secondly, selecting proper raw materials to prepare precursor polyamic acid; and

finally, the modified nano inorganic particles are grafted with polyimide molecules formed by the precursor polyamic acid, so that the novel target polyimide composite material is completed.

The three-step method specifically comprises the following steps:

step S1, which is to add the inorganic nanoparticles for modification into an aqueous alcohol solution (ethanol: water: 95 mL: 5mL), wherein P2O5 particles are taken as an example, but not limited to, specifically, 3 to 5% of P2O5 particles (denoted as compound a) are added into 300 to 400mL of DMAC solvent, then 1 to 3 wt% of silane coupling agent KH-791 (denoted as compound B) is added to form a first mixed solution, mechanical stirring is performed for 1 to 1.5 hours, then the first mixed solution is subjected to ultrasonic dispersion treatment for 1 to 6 hours by using an ultrasonic disperser, and simultaneously heated at a water bath temperature of 40 to 70 ℃, so that the inorganic particles of P2O5 nanometers are uniformly dispersed in the first mixed solution. Wherein the structural formula of the P2O5 is as follows:

wherein the reaction route between the silane coupling agent and the P2O5 particles is as follows:

wherein the particles of coupled P2O5 formed after the reaction were designated as compound C.

Step S2, adding a predetermined precursor polyamic acid preparation raw material into the first mixed solution, for example, including phenylether dianhydride (denoted as compound D) and p-phenylenediamine (denoted as compound E), wherein the molar ratio of the compound D to the compound E is preferably 1:1, uniformly stirring to form a second mixed solution, and reacting, wherein to ensure the reaction is sufficiently performed, a water bath heating mode may be selected, wherein the water bath temperature range is 50-100 ℃, the reaction time is maintained for 5-12 h, and the reaction stirring rotation speed is 300-500 ppm.

Generating bubbles (bubbles) in the solution after the reaction is finished, performing suction filtration on the solution after the reaction in a vacuum environment, performing air extraction treatment on the solution obtained after the suction filtration treatment for about 1 hour by using a vacuum pump, and removing the bubbles in the solution after the reaction; and standing the solution after air extraction at room temperature for 2-4h to further reduce the bubbles in the solution until no bubbles are visible in the solution, so as to form a third mixed solution simultaneously containing the precursor polyamic acid (marked as polymer F) and the modified inorganic P2O5 particles.

Step S3, performing a constant temperature process (Recipe) on the third mixed solution to crosslink and cure the precursor polyamic acid therein to form polyimide, and simultaneously connecting the polyimide molecules by the modified nano inorganic particles P2O5 in a chemical bond manner, and forming an organic-inorganic interface in the molecular structure, thereby finally obtaining the polyimide composite (denoted as polymer G) according to the present invention. The reaction route is as follows: .

Here, the details of the process of step S3 above can be further described in conjunction with the process of forming a polyimide film (PI layer) on a substrate with the polyimide composite material according to the present invention.

Specifically, the third mixed solution containing the precursor polyamic acid and the modified inorganic P2O5 particles obtained in step S2 is spin-coated on a glass substrate 100 in a slit coater manner, then the glass substrate is subjected to an H-VCD process at a temperature range of 110 to 130 ℃ to remove about 70% of the solvent in the polyamic acid solution coated thereon, and then the temperature of the glass substrate is raised and a constant temperature process (Recipe) is performed at a maximum temperature range of 400 to 500 ℃ so that the polyamic acid coated on the glass substrate undergoes a dehydration cyclization reaction to be cross-linked and cured, thereby finally obtaining the polyimide film layer 12 formed on the glass substrate 10, wherein the final structure of the polyimide film layer is shown in fig. 1.

The constant temperature process of the polyamic acid is about 3-5 hours, namely the crosslinking curing process of the polyamic acid lasts for 3-5 hours, wherein the temperature rise speed is 4-10 ℃/min, and the highest temperature in the constant temperature process is in the temperature range of 420-500 ℃.

Further, the baking stage in the constant temperature process is divided into a hard baking mode and a soft baking mode, wherein the hard baking mode is that the temperature is directly raised to the highest temperature, the temperature is kept for about 1 hour, and then the temperature is reduced; and the soft drying is divided into 2 times and more than 2 times of constant temperature platforms, the constant temperature of the constant temperature platform rises in sequence every time, namely the constant temperature of the second constant temperature platform is higher than that of the first constant temperature platform, and finally the temperature is reduced, so that the cross-linking and solvent removal of the precursor polyamic acid at different constant temperature stages are realized. Referring to fig. 2-5, 4 different constant temperature platforms are shown, but not limited thereto.

Further, please refer to fig. 6, which illustrates a thermal expansion coefficient curve of the PI film layer formed by the polyimide composite material according to the present invention. As shown in the figure, the thermal expansion coefficient is 3.766ppm/K within the temperature range of 50-300 ℃, and 6.602ppm/K within the temperature range of 50-400 ℃, and the thermal expansion coefficient of the film layer made of the common polyimide material in the industry is about 12-15 ppm/K, compared with the two phases, the polyimide composite material reinforced by the nano inorganic particles has certain advantages in the parameter performance.

Further, the PI film layer shown in fig. 6 was subjected to a tensile test, while comparing the tensile test of the film layer formed of the conventional polyimide material. As shown in fig. 7, the maximum stress of the PI film layer according to the present invention is increased from 341MPa to 427.5MPa, and the elongation at break is increased from 9.45% to 17.32%, which is a great improvement over the tensile properties of the existing PI film layers, and it is clearly demonstrated that the introduced nano inorganic particles P2O5 play a role in reinforcing the molecular structure of the finally formed polyimide composite according to the present invention.

The preparation method of the polyimide composite material is different from simple blending between nano particles and dianhydride/diamine, but introduces a coupling agent to carry out grafting reaction of the nano inorganic particles to form an aggregation body mechanism taking reinforced nano inorganic particles as a center, then introduces modified nano inorganic particles obtained after modification treatment of the coupling agent into precursor polyamic acid, connects the nano inorganic particles and the precursor polyamic acid in a chemical bond mode through chemical reaction between the nano inorganic particles and the precursor polyamic acid, and forms a novel inorganic-organic interface in a molecular structure, thereby obtaining the nano inorganic particle reinforced polyimide composite material which effectively improves the mechanical property and the thermal stability of the material.

Specifically, the coupling agent selected for the inorganic nanoparticles is a silane coupling agent, such as N- (beta-aminoethyl) -gamma-aminopropyl triethoxy silane, commonly known as silane coupling agent KH-791 (KH-791), which can generate a large amount of hydroxyl groups (-OH) due to hydrolysis, and can be subjected to dehydration condensation polymerization with the hydroxyl groups around the inorganic nanoparticles in the solution to form bonds; in addition, the amino group (-NH 2) at the end of KH-791 can react with the carboxyl group (-COOH) of the precursor polyamic acid, so that KH-791 has a grafting effect, the polyimide molecules formed after the nano inorganic particles and the precursor polyamic acid are crosslinked and cured are connected through chemical bonds, and an organic-inorganic interface is formed in the molecular structure, and the agglomeration among the nano inorganic particles is reduced.

The inorganic nanoparticles reinforce the linear chains in the molecular structure, and the added inorganic nanoparticles are not added by a simple doping method, but are connected with polyimide molecules in a chemical bond connection manner to form an organic-inorganic interface in the molecular structure, so that the mechanical property and the thermal stability of the composite material are improved.

However, it is to be understood that the polyimide composite material according to the present disclosure is not limited to a substrate for an OLED, and may be applied to various suitable applications as long as the performance parameters of a target composite obtained according to different raw material ratios meet requirements.

The technical scope of the present invention is not limited to the contents described in the above description, and those skilled in the art can make various changes and modifications to the above-described embodiments without departing from the technical spirit of the present invention, and these changes and modifications should fall within the scope of the present invention.