POLYIMIDE FILM COMPRISING AT LEAST TWO FILLERS HAVING DIFFERENT DIAMETERS, AND ELECTRONIC DEVICE COMPRISING SAME

Abstract

The present invention provides a polyimide film comprising an inorganic filler, which comprises a first filler group having a diameter (D50) of 2-2.7 μm and a second filler group having an average diameter (D50) of 1-1.7 μm, wherein the polyimide film satisfies relation 1: 0.7≤(D90−D10)/(D50)≤1.2, which is about the respective diameters of the first filler group and the second filler group.

Claims

1. A polyimide film, comprising a base film made of polyimide, and inorganic fillers dispersed in the base film, wherein the polyimide film has a modulus of 3.5 GPa or less, the inorganic fillers include a first filler group having an average particle diameter (D50) falling within the range of 2 μm to 2.7 μm and a second filler group having an average particle diameter (D50) falling within the range of 1 μm to 1.7 μm, and each of the first filler group and the second filler group satisfies the following relational expression 1 for particle diameters:
0.7≤(D90−D10)/D50≤1.2  (1).

2. The polyimide film of claim 1, wherein the first filler group is included in an amount of 60% to 80% by weight and the second filler group is included in an amount of 20% to 40% by weight, based on the total weight of the inorganic fillers.

3. The polyimide film of claim 1, wherein the inorganic fillers further include a third filler group having an average particle diameter (D50) falling within the range of 0.3 μm to 0.6 μm and satisfying the relational expression 1.

4. The polyimide film of claim 3, wherein the third filler group is included in an amount of 5% by weight or more to less than 20% by weight, based on the total weight of the inorganic fillers.

5. The polyimide film of claim 1, wherein the inorganic filler is one or more selected from the group consisting of silica, calcium phosphate, calcium carbonate, and barium sulfate.

6. The polyimide film of claim 5, wherein the inorganic filler is spherical silica.

7. The polyimide film of claim 1, wherein the inorganic filler is included in an amount of 0.05% to 0.3% by weight, based on the total weight of the polyimide film.

8. The polyimide film of claim 1, wherein the first filler group has D90 of 3.0 μm to 4.1 μm and D10 of 1.0 μm to 1.6 μm, and the second filler group has D90 of 1.5 μm to 2.5 μm and D10 of 0.7 μm to 1.2 μm.

9. The polyimide film of claim 3, wherein the third filler group has D90 of 0.4 μm to 0.9 μm and D10 of 0.2 μm to 0.4 μm.

10. The polyimide film of claim 1, wherein a haze of the polyimide film is 12 or less, an average roughness of the polyimide film is 20 nm or more, and the number of surface defects having a long diameter of 30 um or more per unit area of 1 m*1 m of the polyimide film is 10 or less.

11. The polyimide film of claim 1, wherein the polyimide film satisfies the following relational expression 2:
12 μm≤T*L≤40 μm  (2) wherein T is a thickness of the polyimide film and is 30 μm to 50 μm, and L is a transmittance of the polyimide film, is a relative value to 1 which is a theoretical maximum transmittance, and is 0.4 to 0.6.

12. The polyimide film of claim 1, wherein the polyimide forming the base film is derived from imidization of a polyamic acid formed by polymerization of a dianhydride monomer and a diamine monomer.

13. The polyimide film of claim 12, wherein the dianhydride monomer is pyromellitic dianhydride (PMDA), and the diamine monomer is one or more selected from the group consisting of 4,4′-diaminodiphenyl ether (4,4′-ODA), 3,4′-diaminodiphenyl ether (3,4′-ODA), p-methylenedianiline (p-MDA) and m-methylenedianiline (m-MDA).

14. A method of manufacturing the polyimide film of claim 1, the method comprising: polymerizing a dianhydride monomer and a diamine monomer in an organic solvent to prepare a polyamic acid solution; mixing inorganic fillers with the polyamic acid solution to prepare a precursor composition; and forming a film on a support using the precursor composition and performing imidization to form the polyimide film.

15. An electronic device comprising the polyimide film of claim 1 as at least one of an optical film, an insulating film, and a protective film.

16. The electronic device of claim 15, wherein the electronic device is a display device or a wearable instrument whose shape is variably deformed through at least one selected from bending, curving, and rolling, and the polyimide film is deformed together in response to the deformation of the electronic device.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0140] FIG. 1 is a photograph obtained by photographing a surface of a polyimide film according to Example 1.

[0141] FIG. 2 is a photograph obtained by photographing a surface of a polyimide film according to Comparative Example 6.

MODES OF THE INVENTION

[0142] Hereinafter, the action and effect of the present disclosure will be described in more detail through specific examples of the present disclosure. However, these examples are only presented as examples of the invention, and the scope of the invention is not determined by these examples.

Example 1

Preparation Example 1-1 Preparation of a Precursor Composition

[0143] To a 1.0 L reactor was added 515.75 g of dimethylformamide (DMF) as an organic solvent under a nitrogen atmosphere. After setting a temperature to 25° C., 44.27 g of ODA was added as a diamine monomer, followed by stirring for about 30 minutes to confirm that the monomer was dissolved. Thereafter, 46.78 g of PMDA were added as a dianhydride monomer, and finally, the final dose was adjusted and added so that the viscosity became 100,000 cP to 150,000 cP to prepare a polyamic acid solution.

[0144] Thereafter, a precursor composition was prepared by mixing inorganic fillers including a first filler group and a second filler group having the following characteristics in a polyamic acid solution in an amount of 0.15% based on the content of the polyamic acid solid: [0145] First filler group: Spherical silica having an average particle diameter (D50) of 2 μm, D10 of 1.1 μm, D90 of 3.0 μm, 70% by weight based on the total weight of the inorganic fillers; [0146] Second filler group: Spherical silica having an average particle diameter (D50) of 1 μm, D10 of 0.7 μm, D90 of 1.5 μm, 30% by weight based on the total weight of the inorganic fillers.

Preparation Example 1-2 Manufacture of Polyimide Film

[0147] To 100 g of the precursor composition prepared in Preparation Example 1-1 were added 3.0 g of isoquinoline (IQ), 20.8 g of acetic anhydride (AA), and 16.2 g of DMF as a catalyst, the resulting mixture was uniformly mixed and cast on a SUS plate (100SA, Sandvik) at 470 μm using a doctor blade, and dried at a temperature range of 100° C. to 200° C.

[0148] Then, the film was peeled off from the SUS plate, fixed to a pin frame, and transferred to a high-temperature tenter.

[0149] The film was heated from 200° C. to 600° C. in the high-temperature tenter, cooled at 25° C., and separated from the pin frame to obtain a polyimide film having a width*a length of 1 m*1 m and a thickness of 50 μm.

Example 2

[0150] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group and a second filler group having the following characteristics: [0151] First filler group: Spherical silica having an average particle diameter (D50) of 2.7 μm, D10 of 1.5 μm, D90 of 4.1 μm, and 70% by weight based on the total weight of the inorganic fillers; [0152] Second filler group: Spherical silica having an average particle diameter (D50) of 1.7 μm, D10 of 1.2 μm, D90 of 2.5 μm, and 30% by weight based on the total weight of the inorganic fillers.

Example 3

[0153] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group and a second filler group having the following characteristics: [0154] First filler group: Spherical silica having an average particle diameter (D50) of 2.2 μm, D10 of 1.3 μm, D90 of 3.3 μm, and 70% by weight based on the total weight of the inorganic fillers; [0155] Second filler group: Spherical silica having an average particle diameter (D50) of 1.3 μm, D10 of 0.9 μm, D90 of 1.9 μm, and 30% by weight based on the total weight of the inorganic fillers.

Example 4

[0156] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group and a second filler group having the following characteristics: [0157] First filler group: Spherical silica having an average particle diameter (D50) of 2.2 μm, D10 of 1.3 μm, D90 of 3.3 μm, and 80% by weight based on the total weight of the inorganic fillers; [0158] Second filler group: Spherical silica having an average particle diameter (D50) of 1.3 μm, D10 of 0.9 μm, D90 of 1.9 μm, and 20% by weight based on the total weight of the inorganic fillers.

Example 5

[0159] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group, a second filler group, and a third filler group having the following characteristics: [0160] First filler group: Spherical silica having an average particle diameter (D50) of 2 μm, D10 of 1.1 μm, D90 of 3.0 μm, and 70% by weight based on the total weight of the inorganic fillers; [0161] Second filler group: Spherical silica having an average particle diameter (D50) of 1 μm, D10 of 0.7 μm, D90 of 1.5 μm, and 20% by weight based on the total weight of the inorganic fillers; [0162] Third filler group: Spherical silica having an average particle diameter (D50) of 0.3 μm, D10 of 0.2 μm, D90 of 0.42 μm, and 10% by weight based on the total weight of the inorganic fillers.

Example 6

[0163] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group, a second filler group, and a third filler group having the following characteristics: [0164] First filler group: Spherical silica having an average particle diameter (D50) of 2.7 μm, D10 of 1.5 μm, D90 of 4.1 μm, and 70% by weight based on the total weight of the inorganic fillers; [0165] Second filler group: Spherical silica having an average particle diameter (D50) of 1.7 μm, D10 of 1.2 μm, D90 of 2.5 μm, and 20% by weight based on the total weight of the inorganic fillers; [0166] Third filler group: Spherical silica having an average particle diameter (D50) of 0.6 μm, D10 of 0.4 μm, D90 of 0.9 μm, and 10% by weight based on the total weight of the inorganic fillers.

Comparative Example 1

[0167] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group and a second filler group having the following characteristics: [0168] First filler group: Calcium phosphate having an average particle diameter (D50) of 2 μm, D10 of 0.7 μm, D90 of 5.3 μm, and 70% by weight based on the total weight of the inorganic fillers; [0169] Second filler group: Barium sulfate having an average particle diameter (D50) of 1 μm, D10 of 0.4 μm, D90 of 2.3 μm, and 30% by weight based on the total weight of the inorganic fillers.

Comparative Example 2

[0170] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a single filler group having the following characteristics: [0171] Filler group: Calcium phosphate having an average particle diameter (D50) of 2 μm, D10 of 0.7 μm, D90 of 5.3 μm, and 100% by weight based on the total weight of the inorganic fillers.

Comparative Example 3

[0172] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group and a second filler group having the following characteristics: [0173] First filler group: Spherical silica having an average particle diameter (D50) of 3 μm, D10 of 1.7 μm, D90 of 4.7 μm, and 70% by weight based on the total weight of the inorganic fillers; [0174] Second filler group: Spherical silica having an average particle diameter (D50) of 1 μm, D10 of 0.7 μm, D90 of 1.5 μm, and 30% by weight based on the total weight of the inorganic fillers.

Comparative Example 4

[0175] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group and a second filler group having the following characteristics: [0176] First filler group: Spherical silica having an average particle diameter (D50) of 2 μm, D10 of 1.1 μm, D90 of 3.0 μm, and 70% by weight based on the total weight of the inorganic fillers; [0177] Second filler group: Spherical silica having an average particle diameter (D50) of 0.6 μm, D10 of 0.4 μm, D90 of 0.9 μm, and 30% by weight based on the total weight of the inorganic fillers.

Comparative Example 5

[0178] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group and a second filler group having the following characteristics: [0179] First filler group: Spherical silica having an average particle diameter (D50) of 2 μm, D10 of 1.1 μm, D90 of 3.0 μm, and 50% by weight based on the total weight of the inorganic fillers; [0180] Second filler group: Spherical silica having an average particle diameter (D50) of 1 μm, D10 of 0.7 μm, D90 of 1.5 μm, and 50% by weight based on the total weight of the inorganic fillers.

Comparative Example 6

[0181] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group and a second filler group having the following characteristics: [0182] First filler group: Spherical silica having an average particle diameter (D50) of 2 μm, D10 of 0.8 μm, D90 of 3.5 μm, and 70% by weight based on the total weight of the inorganic fillers; [0183] Second filler group: Spherical silica having an average particle diameter (D50) of 1 μm, D10 of 0.3 μm, D90 of 1.8 μm, and 30% by weight based on the total weight of the inorganic fillers.

Comparative Example 7

[0184] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group and a second filler group having the following characteristics: [0185] First filler group: Spherical silica having an average particle diameter (D50) of 2 μm, D10 of 1.5 μm, D90 of 2.6 μm, and 70% by weight based on the total weight of the inorganic fillers; [0186] Second filler group: Spherical silica having an average particle diameter (D50) of 1 μm, D10 of 0.7 μm, D90 of 1.3 μm, and 30% by weight based on the total weight of the inorganic fillers.

Comparative Example 8

[0187] A polyimide film was manufactured in the same manner as in Example 1, except for using inorganic fillers including a first filler group, a second filler group, and a third filler group having the following characteristics: [0188] First filler group: Spherical silica having an average particle diameter (D50) of 2 μm, D10 of 1.1 μm, D90 of 3.0 μm, and 70% by weight based on the total weight of the inorganic fillers; [0189] Second filler group: Spherical silica having an average particle diameter (D50) of 1 μm, D10 of 0.7 μm, D90 of 1.5 μm, and 10% by weight based on the total weight of the inorganic fillers; [0190] Third filler group: Spherical silica having an average particle diameter (D50) of 0.3 μm, D10 of 0.2 μm, D90 of 0.4 μm, and 20% by weight based on the total weight of the inorganic fillers.

[0191] The inorganic fillers used in the above Examples and Comparative Examples are briefly summarized in Table 1 below.

TABLE-US-00001 TABLE 1 Type of First Second Third inorganic filler filler group filler group filler group Characteristics Content D50 D10 D90 Content D50 D10 D90 Content D50 D10 D90 Example 1 Spherical 70 2 1.1 3.0 30 1 0.7 1.5 — — — — silica Example 2 Spherical 70 2.7 1.5 4.1 30 1.7 1.2 2.5 — — — — silica Example 3 Spherical 70 2.2 1.3 3.3 30 1.3 0.9 1.9 — — — — silica Example 4 Spherical 80 2.2 1.3 3.3 20 1.3 0.9 1.9 — — — — silica Example 5 Spherical 70 2 1.1 3.0 20 1 0.7 1.5 10 0.3 0.2  0.42 silica Example 6 Spherical 70 2.7 1.5 4.1 20 1.7 1.2 2.5 10 0.6 0.4 0.9 silica Comp. Calcium 70 2 0.7 5.3 30 1 0.4 2.3 — — — — Example 1 phosphate/ Barium sulfate Comp. Calcium 100 2 0.7 5.3 — — — — — — — — Example 2 phosphate Comp. Spherical 70 3 1.7 4.7 30 1 0.7 1.5 — — — — Example 3 silica Comp. Spherical 70 2 1.1 3.0 30 0.6 0.4 0.9 — — — — Example 4 silica Comp. Spherical 50 2 1.1 3.0 50 1 0.7 1.5 — — — — Example 5 silica Comp. Spherical 70 2 0.8 3.5 30 1 0.3 1.8 — — — — Example 6 silica Comp. Spherical 70 2 1.5 2.6 30 1 0.7 1.3 — — — — Example 7 silica Comp. Spherical 70 2 1.1 3.0 10 1 0.7 1.5 20 0.3 0.2 0.4 Example 8 silica

[0192] Whether or not the fillers used in Examples 1 to 6 and Comparative Examples 1 to 8 satisfy the following relational expression 1 is summarized in Table 2 below:

0.7≤(D90−D10)/(D50)≤1.2  (1).

TABLE-US-00002 TABLE 2 First filler group Second filler group Third filler group Whether or Whether or Whether or Relational not Relational Relational not Relational Relational not Relational expression expression 1 expression expression 1 expression expression 1 1 is satisfied 1 is satisfied 1 is satisfied Example 1 0.95 ◯ 0.80 ◯ — — Example 2 0.96 ◯ 0.76 ◯ — — Example 3 0.91 ◯ 0.77 ◯ — — Example 4 0.91 ◯ 0.77 ◯ — — Example 5 0.95 ◯ 0.80 ◯ 0.73 ◯ Example 6 0.96 ◯ 0.76 ◯ 0.83 ◯ Comp. 2.30 X 1.90 X — — Example 1 — — Comp. 2.30 X — — — — Example 2 Comp. 1.00 ◯ 0.80 ◯ — — Example 3 Comp. 0.95 ◯ 0.83 ◯ — — Example 4 Comp. 0.95 ◯ 0.80 ◯ — — Example 5 Comp. 1.35 X 1.50 X — — Example 6 Comp. 0.55 X 0.60 X — — Example 7 Comp. 0.95 ◯ 0.80 ◯ 0.67 X Example 8

Experimental Example 2: Properties Evaluation of Polyimide Film

[0193] 1) Average roughness evaluation: An average roughness of each polyimide film was measured using a 1S01997 method under the measurement conditions of cut off of 0.25 mm, measurement speed of 0.1 mm/sec, and measurement length of 3 mm per time, and the average value obtained by measuring five times was used. Here, the surface for which the average roughness was measured was an air surface of the polyimide film (the opposite surface of the surface in contact with the plate or the tenter). The above average roughness results are shown in Table 3 below.

[0194] 2) Surface defect evaluation: The surfaces of the polyimide films manufactured in the Examples and the Comparative Examples were observed with a microscope to check the number of defects having a long diameter of 30 um or more per unit area of 1 m*1 m, and the results are shown in Table 3 and FIG. 1 (Example 1), and FIG. 2 (Comparative Example 6).

[0195] 3) Haze evaluation: A haze value was measured on the A light source using a HM150 model.

[0196] 4) Transmittance evaluation: Transmittance was measured by a method presented in ASTM D1003 in the visible light region using a ColorQuesetXE model available from HunterLab, com.

[0197] However, the transmittance is a relative value to 1, which is a theoretical maximum transmittance in an arbitrary object, and is shown in Table 3 below.

TABLE-US-00003 TABLE 3 Average roughness (Number of) (nm) Surface defects Haze Transmittance Example 1 26.1 2 8.1 0.55 Example 2 39.1 3 11.9 0.43 Example 3 30.3 0 9.4 0.51 Example 4 30.7 0 9.0 0.50 Example 5 21.3 1 7.5 0.59 Example 6 34.7 6 11.0 0.45 Comp. Example 1 15.3 53 8.0 0.43 Comp. Example 2 18.5 32 7.3 0.51 Comp. Example 3 45.3 25 10.5 0.47 Comp. Example 4 25.8 18 14.1 0.35 Comp. Example 5 29.2 22 14.8 0.32 Comp. Example 6 42.4 31 8.4 0.47 Comp. Example 7 29.7 13 13.8 0.35 Comp. Example 8 28.1 29 13.3 0.38

[0198] From the results in Table 3, the polyimide films of all Examples in which the relational expression 1 is satisfied, D50, D90, and D10 fall within the range of the present disclosure, and the content of each filler group is also within the scope of the present disclosure, showed an average roughness of 20 nm or more, a haze of 12 or less, a transmittance of 0.4 or more, and an excellent smoothness.

[0199] In addition, it can be seen that the polyimide film of Examples had no surface defects (protrusions). For surface defects, it can be confirmed that the polyimide film has a smooth surface with reference to FIG. 1 obtained by photographing the surface of the polyimide film according to Example 1.

[0200] Meanwhile, it can be seen that in the Comparative Examples where at least one of various factors according to the present disclosure, specifically, a filler group type, a content, a particle diameter, and relational expression 1 is unsatisfactory, at least one of average roughness, haze, transmittance, and smoothness is poor. It should be noted that from the results of these Comparative Examples, the average roughness, transmittance, and smoothness, which are difficult to be compatible with each other, may be compatible at an appropriate level when the experiment is carried out according to the present disclosure.

[0201] In addition, as described above, the Comparative Examples deviating from the present disclosure include a plurality of surface defects, for example, as shown in FIG. 2, and thus include the conventional problem as it is.

Experimental Example 3: Modulus Evaluation of Polyimide Film

[0202] The moduli of the polyimide films of Examples were measured by a method suggested in ASTM D882 using an Instron 5564 model, and measurement results are shown in Table 4.

TABLE-US-00004 TABLE 4 Modulus (GPa) Example 1 3.0 Example 2 2.7 Example 3 2.8 Example 4 3.3 Example 5 3.4 Example 6 2.6

[0203] It can be seen from the results of Table 4 that the polyimide film according to the present disclosure has a modulus of 3.5 GPa or less.

[0204] Although the above description has been made with reference to the embodiments of the present disclosure, a person of ordinary skill in the field to which the present disclosure pertains will be able to make various applications and modifications within the scope of the present disclosure based on the above mentioned.

INDUSTRIAL APPLICABILITY

[0205] The present disclosure described in detail above the advantages of a polyimide film including inorganic fillers, specifically, a polyimide film that satisfies the specific relational expression 1 of the present disclosure and includes inorganic fillers consisting of a plurality of filler groups having different particle diameters.

[0206] In summary, the polyimide film of the present disclosure has substantially no protrusions due to filler aggregation, and may have an average roughness, smoothness, and transmittance at an appropriate level, which are difficult to be compatible with each other by filler groups having different average particle diameters.