TW202103963A - Polyimide multilayer, and manufacturing method thereof - Google Patents

Abstract

This invention provides a polyimide multilayer and a manufacturing method thereof. The polyimide multilayer includes a first hardened-layer and a substrate-layer connected with each other. The first hardened-layer includes a first polyimide and silicon dioxide. The weight ratio of the first polyimide and silicon dioxide is 3:7~7:3. The substrate-layer includes a second polyimide. The first hardened-layer is integrated with the substrate-layer. Thereby, the polyimide multilayer can have both good flexibility and good surface hardness.

Description

Polyimide multilayer structure and manufacturing method thereof

The present invention relates to a polyimide multilayer structure and a manufacturing method thereof, and particularly relates to a polyimide multilayer structure with good softness and good surface hardness.

With the development of technology, traditional display panels and touch panels have been unable to meet consumers' requirements for light, thin, and small electronic products. Therefore, flexible, foldable and flexible electronic products have emerged. It is known that polyimide has the advantages of flexibility, high heat resistance, high transmittance, etc., so it can be used as a raw material for flexible electronic products.

However, in the development of polyimide as a raw material for the panel of flexible electronic products, especially when the polyimide used as the raw material of the cover plate of the outermost layer of the foldable panel is developed, there is often a surface of the polyimide layer. Insufficient hardness. Therefore, the polyimide layer is generally coated with a hard coat to improve its scratch resistance. However, the polyimide layer that has been coated with the hard coat layer is prone to cracks when it is repeatedly bent, which has a negative impact on the user experience of flexible electronic products. Therefore, by directly increasing the surface hardness of the polyimide film to avoid completely relying on the hard coating to improve the scratch resistance, it is a balance between flexibility and hardness. Polyimide is used in foldability The key to a breakthrough in the development of electronic products.

In view of the above problems, the present invention provides a polyimide multilayer structure with good flexibility and good hardness.

A polyimide multilayer structure disclosed in an embodiment of the present invention includes: a first hardened layer comprising a first polyimide and silicon dioxide, the weight of the first polyimide and silicon dioxide The ratio is 3:7-7:3, and a substrate layer includes a second polyimide and is connected to the first hardened layer; wherein, the first hardened layer and the substrate layer are integrally formed .

An embodiment of the present invention discloses a manufacturing method of a polyimide multilayer structure, comprising: preparing a first slurry containing a first diamine, a first dianhydride and silicon dioxide; preparing a second diamine, A second slurry of a second dianhydride; on a support, forming a stack having the second slurry and the first slurry in order from the thickness direction of the support; and heating the stack to A polyimide multilayer structure is integrally formed; wherein, the weight ratio of polyimine to silica in the part formed by the first slurry in the polyimide multilayer structure is 3:7-7:3.

Another embodiment of the present invention discloses a manufacturing method of a polyimide multilayer structure, comprising: preparing a first slurry containing a first diamine, a first dianhydride and silicon dioxide; preparing a second diamine , A second slurry of a second dianhydride; on a support, forming a stack having the first slurry, the second slurry and the first slurry in order from the thickness direction of the support; and The stacked body is heated to integrally form a polyimide multi-layer structure; wherein, the weight ratio of the polyimide to the silicon dioxide of the polyimide multi-layer structure formed by the first slurry is 3:7~ 7:3.

The above-mentioned polyimide multilayer structure disclosed in an embodiment of the present invention includes a hardened layer with good hardness and a flexible substrate layer. The hardening layer includes the first polyimide and silicon dioxide. The base layer includes a second polyimide. Therefore, the polyimide multilayer structure of an embodiment of the present invention has properties such as good flexibility (softness) and good hardness, and can be used as, for example, a substrate material of a display panel or a substrate material of a touch panel.

The above description of the content of the present invention and the description of the following embodiments are used to demonstrate and explain the principle of the present invention and provide a further explanation of the scope of the patent application of the present invention.

The detailed features and advantages of the present invention are described in detail in the following embodiments, and the content is sufficient to enable anyone familiar with the relevant art to understand the technical content of the present invention and implement it accordingly, and in accordance with the content disclosed in this specification, the scope of patent application and the drawings Anyone who is familiar with relevant skills can easily understand the purpose and advantages of the present invention. The following examples further illustrate the viewpoints of the present invention in detail, but do not limit the scope of the present invention by any viewpoint.

The so-called integral formation in some embodiments of the present invention means that when the polyimide multilayer structure is observed under a microscope, no obvious boundaries are observed.

In some embodiments of the present invention, in the thickness direction of the polyimide multilayer structure, the weight percentage of silicon dioxide (the silicon dioxide in a certain layer, by weight, in the polyimide contained in the layer) The ratio of the total weight of amine and silicon dioxide) between two adjacent positions that differ by 5 weight percent is defined as the layer-to-layer boundary. In another part of the embodiments of the present invention, the position where the weight percent of silicon dioxide is 30, 50, or 70 weight percent is defined as the boundary between the layers.

FIG. 1 is a schematic cross-sectional view of a polyimide multilayer structure 100 according to an embodiment of the present invention. As shown in FIG. 1, the polyimide multilayer structure 100 disclosed in an embodiment of the present invention includes a first hardened layer 110 and a substrate layer 120. The base layer 120 is in contact with the first hardened layer 110. The hardened layer 110 has a hardened layer surface 111 away from the base layer 120. In addition, the first hardened layer 110 and the base layer 120 are integrally formed. The operation steps of integrally forming the first hardened layer 110 and the base layer 120 will be described in detail when the manufacturing method of the polyimide multilayer structure 100 is introduced.

The first hardened layer 110 includes a first polyimide and silicon dioxide. The base layer 120 includes a second polyimide. By incorporating silicon dioxide into the first hardened layer 110, the hardness of the hardened layer surface 111 of the first hardened layer 110 can be increased. Moreover, by incorporating silicon dioxide into the first hardened layer 110, the heat resistance of the first hardened layer 110 can also be improved, thereby improving the overall heat resistance of the polyimide multilayer structure 100. In addition, the polyimide multilayer structure 100 can utilize the flexible substrate layer 120 to maintain the polyimide multilayer structure 100 as a whole at appropriate flexural characteristics, thereby facilitating the production of the polyimide multilayer structure 100 . Therefore, the polyimide multilayer structure 100 including the first hardened layer 110 and the base layer 120 can have both good flexibility and good hardness.

In an embodiment of the present invention, the weight ratio of the first polyimide to the silicon dioxide in the first hardened layer 110 is 3:7-7:3, but it is not limited thereto. Among them, the more silicon dioxide is added to the polyimide-containing layer, the higher the heat resistance and surface hardness of the layer. However, if too much silicon dioxide is added to the layer body, it will cause the layer body to become brittle and not resistant to repeated deflection. Therefore, by controlling the weight ratio of the first polyimide to silicon dioxide in the first hardened layer 110 within the aforementioned range, the hardness of the hardened layer surface 111 of the polyimide multilayer structure 100 can be increased. In addition, since the polyimide multilayer structure 100 includes the first hardened layer 110 and the base layer 120, the flexible base layer 120 can be used to maintain the polyimide multilayer structure 100 as a whole with proper flexural characteristics. .

In addition, in an embodiment of the present invention, the substrate layer 120 may also include silicon dioxide. In addition, the weight percentage of silicon dioxide in the base layer 120 is less than the weight percentage of silicon dioxide in the first hardened layer 110. Among them, the weight percentage of silicon dioxide in the base layer 120 is preferably less than 20 weight percentage, but it is not limited thereto. By adding silicon dioxide to the base material layer 120, the hardness of the base material layer 120 can be increased, thereby increasing the hardness of the hardened layer surface 111 of the polyimide multilayer structure 100.

In an embodiment of the present invention, the thickness ratio of the first hardened layer 110 to the base layer 120 is 3:4-5:6, but it is not limited to this. If the first hardened layer 110 is too thin, the surface hardness of the hardened layer of the polyimide multilayer structure 100 will decrease. If the first hardened layer 110 is too thick, the flexibility of the polyimide multilayer structure 100 will decrease. Therefore, when the thickness ratio of the first hardened layer 110 to the base layer 120 is within the aforementioned range, a polyimide multilayer structure 100 having both good hardness and good flexibility can be obtained.

Furthermore, in an embodiment of the present invention, the first polyimine is formed by the condensation polymerization (ie, polycondensation) of the first diamine and the first dianhydride. The second polyimide is formed by condensation polymerization of a second diamine and a second dianhydride.

The first diamine and the second diamine can be selected from 2,2'-bis(trifluoromethyl)benzidine (TFMB, 2,2'-bis(trifluoromethyl)benzidine, Cas.341-58-2), 4,4'-Diaminodiphenyl ether (ODA, 4,4'-Oxydianiline), p-phenylenediamine (PPDA, p-phenylenediamine), 2,2-bis[4-(4-aminophenoxy) Phenyl] propane (HFBAPP, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane), 2,2-bis(trifluoromethyl)-4,4'-diaminophenoxy (6FODA, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether), BTFDPE(4,4'-oxybis[3-(trifluoromethyl)benzeneamine]), FAPQ(4,4'-[1,4-phenylenebis (oxy)]bis[3-(trifluoromethyl)]benzenamine, Cas. No.94525-05-0), FFDA (9,9-Bis(4-amino-3-fluorophenyl)fluorine), 9,9-bis[ One or more of the group formed by 4-(4-amino-3-fluorophenyl)bezene]fluorine or BAFL (9,9-bis(aminophenyl9fluorene)). Among them, one or more selected from the group consisting of aromatic diamines is preferred, but not limited to this. By using aromatic diamines, the surface hardness of the hardened layer of the polyimide multilayer structure can be increased.

The first dianhydride and the second dianhydride can be selected from hexafluoroisopropyl phthalic anhydride (6FDA), triphenyldiether tetracarboxylic dianhydride (HQDPA), biphenyltetracarboxylic dianhydride (BPDA, Cas .2420-87-3), 2,2-bis[(4-(3,4-dicarboxyphenoxy)phenyl)]propane dianhydride (BPADA), pyromellitic dianhydride (PMDA, 1, 2,4,5-benzene tetracarboxylic dianhydride), 2,3,3',4'-biphenyl tetracarboxylic dianhydride (2,3,3',4'-biphenyl tetracarboxylic dianhydride), diphenyl ether tetracarboxylic dianhydride Anhydride (4,4'-oxydiphthalic anhydride), 3,4'-oxydiphthalic anhydride (3,4'-oxydiphthalic anhydride), benzophenonetetracarboxylic dianhydride (benzophenonetetracarboxylic dianhydride), diphenyl sulfide Tetracarboxylic dianhydride (3,3',4,4'-diphenyl sulfonetetracarboxylic dianhydride), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (Cas.No.135876-30-1), 9,9 -bis[4-(3,4-dicarboxyphenoxt)phenyl]fluorene dianhydride (Cas.No.59507-08-3), naphthalene tetracarboxylic dianhydride (1,2,5,6-naphthalene tetracarboxylic dianhydride), naphthalene di Acid anhydride (naphthalenetetracaboxylic dianhydride), bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride, 1,3-bis(3,4-dicarboxyphenyl)- 1,1,3,3-Tetramethyldisiloxane dianhydride (1,3-bis(4'-phthalic anhydride)-tetramethyldisiloxane), BPAF (9,9-bis(3,4-dicarboxyphenyl)fluorine dianhydride ) Or one or more of BP-TME (bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)biphenyl-3,3'-diyl ester). Among them, one or more selected from the group consisting of aromatic dianhydrides is preferred, but not limited to this. By using aromatic dianhydrides, the surface hardness of the hardened layer of the polyimide multilayer structure can be increased.

Among them, the first diamine and the second diamine may be the same or different from each other. The first dianhydride and the second dianhydride may be the same or different from each other. Furthermore, the first polyimide and the second polyimide can also be formed by reacting the same dianhydride monomer and the same diamine monomer. In the case where the first polyimide and the second polyimide contain the same dianhydride and the same diamine, the bonding between the first hardened layer 110 and the base layer 120 can be increased. In addition, when the bonding between the first hardened layer 110 and the base layer 120 is increased, the first hardened layer 110 and the base layer 120 can be prevented from being peeled off.

In addition, in order to take into account both transparency and flexibility, the average particle size of silicon dioxide in an embodiment of the present invention is preferably less than 50 nm, preferably selected from 5 to 15 nm, but not limited to this. With the average particle size of silica within the above range, the polyimide multilayer structure of an embodiment of the present invention can have good transparency and flexibility. Among them, silane coupling agent can also be used for surface treatment. Among them, the silane coupling agent can be selected from one or more of the group consisting of amino silane, epoxy silane, C 8-16 alkyl silane and phenyl silane. Since the silane coupling agent can combine inorganic materials such as silica and organic materials such as polyimide, in one embodiment of the present invention, the silane coupling agent is used for surface treatment, which can make the silica and polyimide good Combine.

Furthermore, in the polyimide multilayer structure 100 of an embodiment of the present invention, the pencil hardness of the hardened layer surface 111 is H or higher. In the present invention, when the proportion of silicon dioxide doped in the layer body is the same, the thicker the layer body, the higher the pencil hardness on the surface of the layer body. If the hardness of the hardened layer surface 111 of the polyimide multilayer structure 100 is higher, the abrasion and scratch resistance characteristics are better. The polyimide multilayer structure 100 according to an embodiment of the present invention includes the first hardened layer 110 and the flexible substrate layer 120, so the polyimide multilayer structure 100 has excellent flexibility and wear resistance. Scratch-resistant characteristics can be applied to foldable covers that require both flexibility and rigidity.

2 is a schematic cross-sectional view of a polyimide multilayer structure 200 according to an embodiment of the present invention. As shown in FIG. 2, the polyimide multilayer structure 200 disclosed in an embodiment of the present invention includes a first hardened layer 210, a base material layer 220 and a second hardened layer 230. The base layer 220 is located between the first hardened layer 210 and the second hardened layer 230. The first hardened layer 210 and the second hardened layer 230 respectively have hardened layer surfaces 211 and 231 away from the base layer 220. In addition, the first hardened layer 210, the base layer 220, and the second hardened layer 230 are integrally formed. The operation steps of integrally forming the first hardened layer 210, the base layer 220, and the second hardened layer 230 will be described in detail when the manufacturing method of the polyimide multilayer structure 200 is introduced.

The first hardened layer 210 includes a first polyimide and silicon dioxide. The base layer 220 includes a second polyimide. The second hardened layer 230 includes the third polyimide and silicon dioxide. Therefore, by incorporating silicon dioxide into the first hardened layer 210 and the second hardened layer 230, the hardness of the hardened layer surfaces 211 and 231 of the first hardened layer 210 and the second hardened layer 230 can be increased. Moreover, by incorporating silicon dioxide into the first hardened layer 210 and the second hardened layer 230, the heat resistance of the first hardened layer 210 and the second hardened layer 230 can also be improved, thereby further improving the polyimide multilayer structure 200 Overall heat resistance. In addition, the polyimide multilayer structure 200 can utilize the flexible substrate layer 220 located in the middle to maintain the polyimide multilayer structure 200 as a whole with proper flexural properties, thereby facilitating the polyimide multilayer structure. 200 production. Therefore, the polyimide multilayer structure 200 including the first hardened layer 210, the base layer 220, and the second hardened layer 230 can have both good flexibility and good hardness.

In an embodiment of the present invention, the weight ratio of the first polyimide to the silicon dioxide in the first hardened layer 210 is 3:7-7:3, but it is not limited thereto. The weight ratio of the third polyimide to silicon dioxide in the second hardened layer 230 is 3:7-7:3, but not limited to this. In addition, the composition of the first hardened layer 210 and the second hardened layer 230 may be different or the same. If the composition of the first hardened layer 210 and the second hardened layer 230 are the same, the first hardened layer 210 and the second hardened layer 230 have the same thermal expansion coefficient, which can prevent the polyimide multilayer structure 200 from being warped and deformed.

In addition, in an embodiment of the present invention, the substrate layer 220 may also include silicon dioxide. Wherein, the weight percentage of the silicon dioxide in the substrate layer 220 is preferably less than 20 weight percentage, but it is not limited thereto. By adding silicon dioxide to the base material layer 220, the hardness of the base material layer 220 can be increased, thereby increasing the hardness of the hardened layer surfaces 211 and 231 of the polyimide multilayer structure 200.

In an embodiment of the present invention, the ratio of the total thickness of the first hardened layer 210 and the second hardened layer 230 to the thickness of the base layer 220 is 3:4-5:3, but it is not limited thereto. The thickness of the first hardened layer 210 and the second hardened layer 230 may be the same or different from each other. If the thickness of the first hardened layer 210 and the second hardened layer 230 are the same, the symmetry of the polyimide multilayer structure 200 in the thickness direction can be improved. Therefore, it is possible to prevent the polyimide multilayer structure 200 from being warped and deformed due to the difference in thickness of the first hardened layer 210 and the second hardened layer 230. Moreover, by the ratio of the total thickness of the first hardened layer 210 and the second hardened layer 230 to the thickness of the base layer 220 within the aforementioned range, a polyimide multilayer structure with good hardness and good flexibility can be obtained. 200.

Furthermore, in the polyimide multilayer structure 200 of an embodiment of the present invention, the pencil hardness of the hardened layer surfaces 211 and 231 is H or higher. If the hardness of the hardened layer surfaces 211 and 231 of the polyimide multilayer structure 200 is higher, the abrasion and scratch resistance properties will be better. The polyimide multilayer structure 200 of one embodiment of the present invention includes a first hardened layer 210, a second hardened layer 230, and a flexible substrate layer 220, so the polyimide multilayer structure 200 has excellent Flexibility, abrasion resistance and scratch resistance, can be applied to foldable covers that require both flexibility and hardness.

The thermal expansion coefficient of the polyimide multilayer structure in some embodiments of the present invention is lower than 60 ppm/°C, but it is not limited thereto. Among them, the lower the thermal expansion coefficient, the closer to the thermal expansion coefficient of the circuit layer material (for example: copper foil), which can avoid problems such as the circuit layer being unable to conduct normally due to the large difference between the thermal expansion coefficient and the circuit layer material. Since the polyimide multilayer structure of the embodiment of the present invention has a thermal expansion coefficient close to that of a circuit layer material of a common flexible printed circuit board, it can be applied to a substrate of a flexible printed circuit board.

Since the polyimide multilayer structure disclosed in an embodiment of the present invention has high flexibility and hardness, it can be used as a flexible plastic substrate. And, in the fields of liquid crystal display (LCD), flexible organic light emitting diode (flexible OLED), touch panel (touch panel), flexible printed circuit board (FPC), e-book, etc. Among them, the use of the polyimide multilayer structure of the present invention can provide designers with great design flexibility. In addition, the polyimide multilayer structure disclosed in an embodiment of the present invention has good heat resistance, and therefore can withstand high temperatures in the semiconductor manufacturing process.

The preparation method of the polyimide multilayer structure of the present invention is as follows, but the following experimental methods are only illustrative, and the scope of the present invention is not limited by the following experimental methods.

In the manufacturing method of the polyimide multilayer structure of an embodiment of the present invention, the method of preparing the slurry is not particularly limited. The polyimide solution can be prepared first and then mixed with the silica solution to form the slurry, or Directly mix dianhydride, diamine and silicon dioxide into a slurry. Among them, if a slurry containing a polyimide solution is used, the heating temperature conditions required to form a polyimide multilayer structure can be greatly reduced. Therefore, by using a slurry containing a polyimide solution, yellowing caused by high-temperature heating can be avoided, and the transparency of the polyimide multilayer structure can be improved.

In the manufacturing method of the polyimide multilayer structure according to an embodiment of the present invention, first, a first slurry containing a first polyimide solution and silicon dioxide is prepared (S101). Specifically, the first slurry is used to form the first hardened layer. Dissolve the first diamine in the solvent to form the first diamine solution, add the first dianhydride with an equivalent of 0.98~1.02 moles to 1 mole of the first diamine into the first diamine solution, and heat to 180~ 200°C and catalyzed by tertiary amine to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimide is 20% by weight. Dilute the silicon dioxide solution that has been surface-treated with phenylsilane to a concentration of 20% by weight of the solid content of the silicon dioxide that has been surface-treated with phenylsilane. The first slurry is prepared according to the predetermined ratio of polyimide to silica.

Then, a second slurry containing the second polyimide solution is prepared (S102). Specifically, the second slurry is used to form the base material layer. Dissolve the second diamine in the solvent to form a second diamine solution, add the second dianhydride with a molar equivalent of 0.98~1.02 mol to 1 mol of the second diamine into the second diamine solution, and heat to 180~ 200°C and catalyzed by tertiary amine to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimine is 20% by weight to form a second slurry. In addition, silicon dioxide may also be included in the second slurry.

The solvents in steps S101 and S102 include, for example, dimethylformamide (DMF), N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone, NMP), N,N-dimethylacetamide (N , N-dimethylacetamide, DMAc), m-cresol, γ-butyrolactone (GBL) or a combination of the above.

Examples of tertiary amines in steps S101 and S102 include: triethylenediamine (DABCO, Triethylenediamine), N,N-dimethylcyclohexylamine (N,N-Dimethylcyclohexylamine), 1,2-dimethylimidazole ( 1,2-Dimethylimidazole), trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, triethylenediamine, N-methyl Pyrrolidine, N-ethylpyrrolidine, N-methylhexahydropyridine, N-ethylhexahydropyridine, imidazole, pyridine, picoline, lutidine, quinoline or isoquinoline.

Then, a stacked body including the first slurry and the second slurry is formed (S103). In detail, the step S103 of forming a stack containing the first slurry and the second slurry can use, for example, "coating the first slurry on the support, then heating the first slurry until it is not completely dry, and then coating the second slurry On the incompletely dried first slurry" method (A), or "coextrude the first slurry and the second slurry on the support" method (B), etc. are used to form a polyimide in one piece Multi-layer structure method. Among them, the so-called "heating the first slurry until it is not completely dry" means, for example, heating to volatilize the solvent in the first slurry so that the weight of the first slurry after heating is 25-85% (with 30 ～50% is better).

In the method (A), the first slurry is coated on the support in such a manner that the thickness is 15 μm-25 μm. Then, the first slurry is heated at 80° C. for 5 to 10 minutes, so that the first slurry is in an incompletely dried state. Then, the second slurry is coated on the incompletely dried first slurry with a thickness of 20 μm-30 μm.

In method (B), the thickness ratio of the first slurry and the second slurry is 3:4 to 5:6 (for example, the thickness of the first slurry is 15 μm to 25 μm, The second slurry (20 μm-30 μm in thickness) is co-extruded on the support.

Forming a stack containing the first slurry and the second slurry by the method (A) or the method (B), etc., can increase the gap between the layer formed by the first slurry and the layer formed by the second slurry. Binding force. Therefore, this integral molding method has the advantage of preventing the layers in the polyimide multilayer structure from being peeled off easily.

Moreover, in the manufacturing method of the polyimide multilayer structure of an embodiment of the present invention, the order of forming the layer on the support is not particularly limited. The layer formed by the first slurry can be formed first, and then the layer formed by the first slurry can be formed. For the layer formed by the two slurries, the layer formed by the second slurry may be formed first, and then the layer formed by the first slurry can be formed.

Then, the stacked body is heated to integrally form a polyimide multilayer structure (S104). In detail, the stacked body is heated to 210° C. for one hour to form a polyimide multilayer structure integrally. Among them, the temperature of heating the stacked body is not limited to 210°C. If the first and second slurries are prepared with polyamide acid, the stacked body needs to be heated at 260°C to 400°C for imidization. . Thereby, a polyimide multilayer structure having the first hardened layer and the base layer is integrally formed.

Furthermore, in the manufacturing method of the polyimide multilayer structure 200 according to another embodiment of the present invention, first, a first slurry containing a first polyimide solution and silicon dioxide is prepared (S201). Specifically, the first slurry is used to form the first hardened layer. The first diamine is dissolved in the solvent to form the first diamine solution, and the first dianhydride with 0.98~1.02 molar equivalent relative to 1 mol of the first diamine is added to the first diamine solution In the process, it is heated to 180~200℃ and catalyzed by tertiary amine to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a solid content of 20 weight percent. Dilute the silicon dioxide solution that has been surface-treated with phenylsilane to a concentration of 20% by weight of the solid content of the silicon dioxide that has been surface-treated with phenylsilane. The first slurry is prepared according to the predetermined ratio of polyimide to silica.

Then, a second slurry containing the second polyimide solution is prepared (S202). Specifically, the second slurry is used to form the base material layer. Dissolve the second diamine in the solvent to form a second diamine solution, add the second dianhydride with a molar equivalent of 0.98~1.02 mol relative to 1 mol of the second diamine into the second diamine solution, and heat to 180~ 200°C and catalyzed by tertiary amine to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimine solution is 20% by weight to form a second slurry. In addition, silicon dioxide may also be included in the second slurry.

Then, a third slurry containing a third diamine, a third dianhydride, and silicon dioxide is prepared (S203). Specifically, the third slurry is used to form the second hardened layer. Dissolve the third diamine in a solvent to form a third diamine solution, add the third dianhydride with an equivalent of 0.98 to 1.02 moles relative to 1 mole of the third diamine into the third diamine solution, and heat to 180~ 200°C and catalyzed by tertiary amine to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimide solution is 20 weight percent. Take the silicon dioxide solution that has been surface-treated with phenylsilane and dilute it to a concentration of 20% by weight of the solid content of the silicon dioxide that has been surface-treated with phenylsilane. The third slurry is prepared according to the predetermined ratio of polyimide to silica. It is also possible to directly use the first slurry as the third slurry.

The solvents in steps S201, S202, and S203 can be, for example, the same as the solvents described above.

Then, a stacked body including the first slurry, the second slurry, and the third slurry is formed (S204). In detail, the step S204 of forming a stack including the first slurry, the second slurry, and the third slurry can use, for example, "coating the first slurry on the support, and then heating the first slurry until the first slurry is incomplete. Dry, and then apply the second slurry on the incompletely dried first slurry, and then heat the second slurry to not completely dry, and then apply the third slurry on the incompletely dried second slurry" method (A '), or "the first slurry, the second slurry, and the third slurry are co-extruded on the support" method (B') and other methods for integrally forming the polyimide multilayer structure. Among them, the so-called "heating the first slurry until it is not completely dry" means, for example, heating to volatilize the solvent in the first slurry so that the weight of the first slurry after heating is 25-85% (with 30 ～50% is better). The so-called "heating the second slurry until it is not completely dry" means, for example, heating to volatilize the solvent in the second slurry so that the weight of the second slurry after heating is 25-85% (with 30-50%) of the weight of the second slurry after being coated on the support. % Is better).

In the method (A'), the first slurry is coated on the support so that the thickness is 15 μm-25 μm. Then, the first slurry is heated at 80° C. for 5 to 10 minutes, so that the first slurry is in an incompletely dried state. Then, the second slurry is coated on the incompletely dried first slurry with a thickness of 20 μm-30 μm. Then, the second slurry is heated at 80° C. for 5 to 10 minutes to make the second slurry in an incompletely dried state. Then, the third slurry is coated on the incompletely dried second slurry with a thickness of 15 μm-25 μm.

In method (B'), the ratio of the total thickness of the first slurry and the third slurry to the thickness of the second slurry is 3:4 to 5:3 ( For example: the first slurry has a thickness of 15 μm-25 μm, the second slurry has a thickness of 20 μm-30 μm, and the third slurry has a thickness of 15 μm-25 μm) co-extruded on the support.

Method (A') and method (B') are the same as method (A) and method (B), which can increase the bonding force between the layer body and the layer body. Therefore, the method (A') and the method (B') and other integrated molding methods also have the advantage of preventing the layers in the polyimide multilayer structure from being peeled off.

Moreover, in the manufacturing method of the polyimide multilayer structure of an embodiment of the present invention, the order of forming the layer on the support is not particularly limited. The layer formed by the first slurry can be formed first, and then the layer formed by the first slurry can be formed. The layer formed by the two slurries, and finally the layer formed by the third slurry. In this manufacturing method, a layer formed by the third slurry can be formed first, then a layer formed by the second slurry can be formed, and finally a layer formed by the first slurry can be formed.

Next, the stacked body is heated to integrally form a polyimide multilayer structure (S205). In detail, the stacked body is heated to 210° C. for one hour to form a polyimide multilayer structure integrally. The temperature of heating the stack is not limited to 210°C. If the first, second and third slurries are prepared with polyamic acid, the stack can be heated at 260°C to 400°C to carry out imidization reaction. ). Thereby, a polyimide multilayer structure having the first hardened layer and the second hardened layer of the base material layer is integrally formed.

Hereinafter, several embodiments and comparative examples are used to illustrate the polyimide multilayer structure disclosed in this proposal, and experimental tests are performed to compare the difference in properties.

Example 1

A first slurry for forming the first hardened layer is prepared. Dissolve TFMB in a mixed solvent of DMAc/GBL to form a TFMB solution. Add 6FDA with a molar equivalent of 0.98 to 1.02 molar equivalent to 1 mol of TFMB. Add 6FDA to the TFMB solution, heat it to 180 to 200°C and use isoquinoline as a catalyst. Catalysis is performed to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimide is 20% by weight. Dilute the silicon dioxide solution that has been surface-treated with phenylsilane to a concentration of 20% by weight of the solid content of the silicon dioxide that has been surface-treated with phenylsilane. Prepare the first slurry according to the ratio of polyimide:silica dioxide=7:3. Then, a second slurry for forming the substrate layer is prepared. Dissolve TFMB in a mixed solvent of DMAc/GBL to form a TFMB solution. Add 6FDA with a molar equivalent of 0.98~1.02 molar equivalent to 1 molar TFMB into the TFMB solution, heat it to 180~200℃ and use isoquinoline as a catalyst Catalysis is performed to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimine is 20% by weight to form a second slurry. Then, a stacked body including the first slurry and the second slurry is formed. In the stacked body, the first thickness of the portion formed by the first slurry (hereinafter referred to as the first thickness) is 25 μm, and the second thickness of the portion formed by the second slurry in the stack (hereinafter (Referred to as the second thickness for short) is 30 μm. Then, the stacked body was heated at 80°C, 160°C, and 210°C for one hour each in sequence. Thereby, a polyimide multilayer structure having the first hardened layer and the base layer is integrally formed.

Example 2

Dissolve TFMB in a mixed solvent of DMAc/GBL to form a TFMB solution. Add 6FDA with a molar equivalent of 0.98 to 1.02 molar equivalent to 1 mol of TFMB. Add 6FDA to the TFMB solution, heat it to 180 to 200°C and use isoquinoline as a catalyst. Catalysis is performed to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimide is 20% by weight. Take the silicon dioxide solution that has been surface-treated with phenylsilane, and dilute it to a concentration of 20% by weight of the solid content of the silicon dioxide that has been surface-treated with phenylsilane. Prepare the first slurry according to the ratio of polyimide:silica dioxide=7:3. And, directly use the first slurry as the third slurry. Then, a second slurry for forming the substrate layer is prepared. Dissolve TFMB in a mixed solvent of DMAc/GBL to form a TFMB solution. Add 6FDA with a molar equivalent of 0.98~1.02 molar equivalent to 1 molar TFMB into the TFMB solution, heat it to 180~200℃ and use isoquinoline as a catalyst Catalysis is performed to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimine is 20% by weight to form a second slurry. Then, a stacked body including the first slurry, the second slurry, and the third slurry is formed. In the stacked body, the first thickness is 25 μm and the second thickness is 30 μm. The third thickness (hereinafter referred to as the third thickness) of the part formed by the third slurry in the stacked body is 23 μm. Then, the stacked body was heated at 80°C, 160°C, and 210°C for one hour each in sequence. Thereby, a polyimide multilayer structure having a first hardened layer, a base layer and a second hardened layer is integrally formed.

Example 3

Except for the matters described below, a polyimide multilayer structure was produced in accordance with Example 2. ‧When preparing the second slurry, add silica and prepare the second slurry according to the ratio of polyimide:silica =85:15.

Example 4

Except for the matters described below, a polyimide multilayer structure was produced in accordance with Example 2. ‧When preparing the first slurry, prepare the first slurry according to the ratio of polyimide:silica dioxide=1:1.

Example 5

Except for the matters described below, a polyimide multilayer structure was produced in accordance with Example 2. ‧When preparing the first slurry, prepare the first slurry according to the ratio of polyimide:silica dioxide=1:1. ‧When preparing the second slurry, add silica and prepare the second slurry according to the ratio of polyimide:silica =85:15.

Example 6

Except for the matters described below, a polyimide multilayer structure was produced in accordance with Example 2. ‧When preparing the first slurry, prepare the first slurry according to the ratio of polyimide:silica dioxide=3:7.

Example 7

Except for the matters described below, a polyimide multilayer structure was produced in accordance with Example 2. ‧When preparing the first slurry, prepare the first slurry according to the ratio of polyimide:silica dioxide=3:7. ‧When preparing the second slurry, add silica and prepare the second slurry according to the ratio of polyimide:silica =85:15.

Example 8

Except for the matters described below, a polyimide multilayer structure was produced in accordance with Example 2. ‧The first thickness is changed to 15 μm, the second thickness is changed to 20 μm, and the third thickness is changed to 14 μm.

Example 9

Except for the matters described below, a polyimide multilayer structure was produced in accordance with Example 2. ‧When preparing the second slurry, add silica and prepare the second slurry according to the ratio of polyimide:silica =85:15. ‧The first thickness was changed to 15 μm, the second thickness was changed to 21 μm, and the third thickness was changed to 14 μm.

Comparative example 1

Dissolve TFMB in a mixed solvent of DMAc/GBL to form a TFMB solution. Add 6FDA with a molar equivalent of 0.98 to 1.02 molar equivalent to 1 mol of TFMB. Add 6FDA to the TFMB solution, heat it to 180 to 200°C and use isoquinoline as a catalyst. Catalysis is performed to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimine is 20% by weight to form a slurry. Then, the slurry was coated on the support, and baked at 80°C, 160°C, and 210°C for one hour each. Thereby, a polyimide layer having a single-layer thickness of 74 μm was formed.

Comparative example 2

Dissolve TFMB in a mixed solvent of DMAc/GBL to form a TFMB solution. Add 6FDA with a molar equivalent of 0.98~1.02 molar equivalent to 1 molar TFMB into the TFMB solution, heat it to 180~200℃ and use isoquinoline as a catalyst Catalysis is performed to prepare polyimide solution by dehydration reaction. Then, the polyimide solution is diluted to a concentration where the solid content of the polyimide is 20% by weight. Dilute the silicon dioxide solution that has been surface-treated with phenylsilane to a concentration of 20% by weight in terms of solid content of the silicon dioxide that has been surface-treated with phenylsilane. According to the ratio of polyimide:silica dioxide=85:15, the slurry is prepared. Then, the slurry was coated on the support, and baked at 80°C, 160°C, and 210°C for one hour each. Thereby, a single-layer polyimide layer having a thickness of 75 μm was formed.

Comparative example 3

Except that the second slurry was prepared according to the ratio of polyimide:silica dioxide=7:3 when preparing the slurry, the operation was performed in accordance with Comparative Example 2, and a single-layer polyimide layer with a thickness of 77 μm was formed.

Comparative example 4

Except that the second slurry was prepared according to the ratio of polyimide:silica dioxide=6:4 when preparing the slurry, the operation was performed in accordance with Comparative Example 2 to form a single-layer polyimide layer with a thickness of 78 μm. .

Test 1

Mechanical and thermal properties

The test includes Young's coefficient (expressed in GPa), CTE (expressed in ppm/℃) and pencil hardness. Young's coefficient is measured by universal tensile machine in accordance with ASTM 882 standard test method. CTE is measured by the thermomechanical analyzer TMA/SDTA LF1100 (made by METTLER TOLEDO), under thermal adversity that changes between 50°C and 200°C (the rate of change is about 10°C/min), and the standard load-bearing force is applied (For example, about 0.02 N), measure the stretch of the film. The pencil hardness system uses a manual pencil hardness tester (PPH-1000, load 750 g, Japan Mitsubishi JIS hardness test pencil), with a fixed speed of 10 mm/sec and an angle of 45 degrees, to test the resistance of the polyimide multilayer structure The highest hardness. The results are shown in Table 1

Test 2

Bending test

After bending the polyimide multilayer structure using the bending tester YUASA DLDMLH-FS, visually observe the polyimide multilayer structure. After 20,000 bending operations with a radius of curvature of 3 mm, the appearance without obvious creases is marked as "○". After 2,000 times of bending operations with a radius of curvature of 3 mm, the appearance without obvious creases is "△". After 20,000 times of bending operations with a radius of curvature of 3 mm and 2,000 times of bending operations with a radius of curvature of 3 mm, those with obvious creases on the appearance are marked as "╳". The results are shown in Table 1.

In Table 1, "L1" indicates the first hardened layer, "L2" indicates the base layer, "L3" indicates the second hardened layer, and "PI" indicates polyimide.

Table 1 Example Level PI (weight percentage) Silicon dioxide (weight percentage) Thickness after baking (μm) Young's coefficient (Gpa) CTE (ppm/°C) Pencil hardness Bending test 1 L1 70 30 25 3.83 56.79 2H ○ L2 100 0 30 2 L1 70 30 25 3.78 53.36 2H ○ L2 100 0 30 L3 70 30 twenty three 3 L1 70 30 25 3.86 51.82 2H ○ L2 85 15 31 L3 70 30 twenty four 4 L1 50 50 26 4.15 48.61 3H ○ L2 100 0 29 L3 50 50 twenty four 5 L1 50 50 26 4.31 46.33 3H ○ L2 85 15 30 L3 50 50 twenty three 6 L1 30 70 27 5.26 45.12 4H △ L2 100 0 29 L3 30 70 twenty three 7 L1 30 70 26 5.53 43.08 4H △ L2 85 15 30 L3 30 70 25 8 L1 70 30 15 3.99 52.81 H ○ L2 100 0 20 L3 70 30 14 9 L1 70 30 15 4.12 51.29 1~2H ○ L2 85 15 twenty one L3 70 30 14 Comparative example Level PI (weight percentage) Silicon dioxide (weight percentage) Thickness (μm) Young's coefficient (Gpa) CTE (ppm/°C) Pencil hardness Bending test 1 100 0 74 3.11 58.62 HB ○ 2 85 15 75 3.42 55.31 Less than H ○ 3 70 30 77 3.83 51.25 2H ╳ 4 60 40 78 - - Brittle, not easy to remove -

As shown in Table 1, Comparative Example 1 only contains PI. Although the elongation rate is higher and the flexibility is better, the pencil hardness is insufficient, and the surface is easily damaged. In contrast, the pencil hardness of the polyimide multilayer structure with the hardened layer and the base layer in Examples 1, 2, 4, 6, and 8 are all above H. Therefore, the polyimide disclosed in the embodiments of the present invention The surface of the imine multilayer structure away from the substrate layer has excellent abrasion and scratch resistance.

Furthermore, as shown in Comparative Examples 1 to 4 in Table 1, it can be seen that although adding more silicon dioxide to a single-layer polyimide layer can increase the pencil hardness of the layer body, as the hardness increases, the layer The body will also become brittle and difficult to remove. In contrast, the polyimide multilayer structure disclosed in the embodiments 1 to 7 of the present invention is manufactured by stacking a hardened layer and a substrate layer, which can improve the polyimide disclosed in the embodiments of the present invention. The flexibility of the multilayer structure. The proportion of silicon dioxide contained in the polyimide multilayer structure disclosed in Examples 1 to 7 of the present invention is higher than the proportion of silicon dioxide contained in the polyimide layer disclosed in Comparative Examples 1 to 3. Therefore, the polyimide multilayer structure disclosed in Examples 1-7 of the present invention has excellent surface hardness. Therefore, by the manufacturing method disclosed in the present invention, a polyimide multilayer structure with excellent flexibility and surface hardness can be obtained.

In addition, it can be seen from Examples 2 and 8 that when the composition is the same, the thicker the total thickness of the polyimide multilayer structure, the higher the pencil hardness. Specifically, in the case of the same composition, if the total thickness is 50 μm or more, the pencil hardness can reach H or more. If the total thickness is 80 μm or more, the pencil hardness can reach 2H or more. Furthermore, it can be seen from Examples 2, 4, and 6, that when the thickness is the same, the higher the proportion of silicon dioxide contained in the hardened layer, the higher the pencil hardness.

In summary, the polyimide multilayer structure disclosed in an embodiment of the present invention can have both good flexibility and good hardness by including a hardened layer with high hardness and a flexible substrate layer.

Although the embodiments of the present invention are disclosed as described above, they are not intended to limit the present invention. Anyone who is familiar with related arts, without departing from the spirit and scope of the present invention, includes all the shapes, structures, and features described in the scope of the present invention. And the spirit can be changed slightly, so the patent protection scope of the present invention shall be subject to the definition of the patent application attached to this specification.

100: Polyimide multilayer structure 110: The first hardened layer 111: Hardened layer surface 120: substrate layer 200: Polyimide multilayer structure 210: first hardened layer 211: Hardened layer surface 220: substrate layer 230: second hardened layer 231: Hardened layer surface

Fig. 1 is a schematic cross-sectional view of a polyimide multilayer structure according to an embodiment of the present invention. 2 is a schematic cross-sectional view of a polyimide multilayer structure according to an embodiment of the present invention. Fig. 3 is a manufacturing flow chart of a polyimide multilayer structure according to an embodiment of the present invention. Fig. 4 is a manufacturing flow chart of a polyimide multilayer structure according to an embodiment of the present invention.

100: Polyimide multilayer structure

110: The first hardened layer

111: Hardened layer surface

120: substrate layer

Claims (18)

A polyimide multilayer structure, comprising: a first hardened layer, comprising a first polyimide and silicon dioxide, the weight ratio of the first polyimide to silicon dioxide is 3:7-7: 3, and a substrate layer, including a second polyimide, and connected with the first hardened layer; wherein, the first hardened layer and the substrate layer are integrally formed. The polyimide multilayer structure according to claim 1, wherein the base material layer further comprises silicon dioxide, and the weight percentage of silicon dioxide in the base material layer is less than that of silicon dioxide in the first curing The weight percentage of the layer. The polyimide multilayer structure according to claim 1, wherein the ratio of the thickness of the first hardened layer to the thickness of the substrate layer is 3:4 to 5:6. The polyimide multilayer structure according to claim 1, wherein the first polyimine and the second polyimine are formed by reacting the same dianhydride monomer and the same diamine monomer. The polyimide multilayer structure according to claim 1, further comprising a second hardened layer, and the base material layer is located between the first hardened layer and the second hardened layer, and the first hardened layer, The base layer and the second hardened layer are integrally formed. The polyimide multilayer structure according to claim 5, wherein the second hardened layer comprises a third polyimide and silicon dioxide, and the weight ratio of the third polyimide to silicon dioxide is 3: 7～7:3. The polyimide multilayer structure according to claim 5, wherein the ratio of the total thickness of the first hardened layer and the second hardened layer to the thickness of the substrate layer is 3:4 to 5:3. The polyimide multilayer structure according to claim 5, wherein the first hardened layer and the second hardened layer have the same composition. The polyimide multilayer structure according to any one of claim 1 to claim 8, wherein the pencil hardness of a surface far from the substrate layer is H or higher. A manufacturing method of a polyimide multilayer structure, comprising: forming a stack that includes a first slurry and a second slurry, the second slurry is located on the surface of the first slurry, and the first slurry includes a first slurry A polyimide and silica or a first polyimide and silica, and the second slurry includes a second polyimide or a second polyimide; and The stacked body is heated to integrally form a polyimide multi-layer structure; wherein the weight ratio of the first polyimide to the silicon dioxide in the portion of the polyimide multi-layer structure formed by the first slurry is 3:7～7:3. The manufacturing method according to claim 10, wherein the second slurry further contains silicon dioxide, and the weight percentage of silicon dioxide in the second slurry is less than the weight percentage of silicon dioxide in the first slurry Percent by weight. The manufacturing method according to claim 10, wherein the step of forming the stacked body including the first slurry and the second slurry comprises: coating the first slurry on a support; heating the first slurry to incomplete Dry, and then coat the second slurry on the incompletely dried first slurry. The manufacturing method according to claim 10, wherein the step of forming the stack including the first slurry and the second slurry comprises: co-extruding the first slurry and the second slurry on a support. The manufacturing method according to claim 10, wherein the portion of the stack formed by the first slurry has a first thickness, the portion of the stack formed by the second slurry has a second thickness, and the first The ratio of the thickness to the second thickness is 3:4-5:6. The manufacturing method according to claim 10, wherein the stack further includes a third slurry, the second slurry is located between the first slurry and the third slurry, and the third slurry includes a third polyamide Amine and silica or containing a third polyimide and silica, the weight of the third polyimide and silica in the part formed by the third slurry in the polyimide multilayer structure The ratio is 3:7-7:3. The manufacturing method according to claim 15, wherein the step of manufacturing the stack including the first slurry, the second slurry, and the third slurry on the support includes: coating the first slurry on a support On; heating the first slurry to not completely dry, and then coating the second slurry on the incompletely dried first slurry; heating the second slurry to not completely dry, and then coating the third slurry on the incomplete Dry on the second slurry. The manufacturing method according to claim 15, wherein the step of forming the stack including the first slurry, the second slurry, and the third slurry includes: the first slurry, the second slurry, and the third slurry Co-extruded on a support. The manufacturing method according to claim 15, wherein the portion of the stacked body formed by the first slurry has a first thickness, the portion of the stacked body formed by the second slurry has a second thickness, and the stacked body The part formed by the third slurry has a third thickness, and the ratio of the total thickness of the first thickness and the third thickness to the second thickness is 3:4-5:3.

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