POLYIMIDE AND MANUFACTURING METHOD THEREFOR

Abstract

The present application relates to a polyimide and a manufacturing method therefor, thereby providing a polyimide capable of implementing excellent adhesion force while maintaining the inherent characteristics of the polyimide, and a manufacturing method therefor.

Claims

1. A polyimide comprising a polymer in which a diamine monomer and a dianhydride monomer are polymerized, wherein the average light transmittance in a wavelength region of 380 nm to 780 nm is in a range of 49 to 61%, and the light transmittance at a wavelength of 550 nm is in a range of 40 to 64%.

2. The polyimide according to claim 1, wherein the polymer comprises first chains and second chains shorter than the first chains, and the second chains are in an oxidized state.

3. The polyimide according to claim 2, wherein the oxidized second chains are included in a range of 5 wt % or less in the total polymer.

4. The polyimide according to claim 1, wherein the diamine monomer comprises 3,5-diamino benzoic acid, 3,3-dihydroxy-4,4-diamino-biphenyl, 2,5-dihydroxy-p-phenylenediamine, 4,6-diaminoresorcinol, 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene or 4,4′-methylenediamine (MDA).

5. The polyimide according to claim 1, wherein the dianhydride monomer comprises pyromellitic dianhydride (PMDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA) or 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA).

6. The polyimide according to claim 1, wherein the diamine monomer comprises at least one or more hydroxyl groups in the molecular structure.

7. The polyimide according to claim 1, wherein the thermal decomposition temperature is 560° C. or more.

8. The polyimide according to claim 1, wherein the glass transition temperature is 360° C. or more.

9. The polyimide according to claim 1, wherein the coefficient of thermal expansion (CTE) is 15 ppm/° C. or less.

10. The polyimide according to claim 11, being imidized under a nitrogen and oxygen atmosphere.

11. The polyimide according to claim 1, wherein the adhesion force measured, according to ASTM D 3359, while attaching the polyimide to a glass substrate to have a width of 10 mm and peeling it at a peel rate of 20 mm/min and a peel angle of 180° is 0.08N/cm or more.

12. A method for manufacturing a polyimide, comprising imidizing a polyimide precursor composition under a nitrogen and oxygen atmosphere.

13. The method for manufacturing a polyimide according to claim 12, wherein the nitrogen and oxygen have volume ratios of 95 to 5 and 5 to 95, respectively.

14. The method for manufacturing a polyimide according to claim 12, having a process temperature of 50 to 500° C.

15. The method for manufacturing a polyimide according to claim 12, wherein the polyimide having the form of a film with a thickness of 5 to 50 μm is manufactured.

16. The method for manufacturing a polyimide according to claim 12, wherein the polyimide precursor composition has solid contents in a range of 5 to 30 wt %.

17. The method for manufacturing a polyimide according to claim 12, wherein the polyimide precursor composition has a viscosity of 10,000 cP or less as measured by a Brookfield viscometer in the RV-7 spindle under conditions of a temperature of 23° C. and a rotation speed of 0.5 rpm.

Description

BEST MODE

[0049] Hereinafter, the present invention will be described in more detail through Examples according to the present invention and Comparative Examples not according to the present invention, but the scope of the present invention is not limited by Examples presented below.

Example 1

[0050] N-methyl-pyrrolidone (NMP) was introduced into a 500 ml reactor equipped with a stirrer and nitrogen injection and discharge tubes while nitrogen was injected thereto, and after the temperature of the reactor was set to 30° C., 1,4-diaminobenzene (PPD) as a diamine monomer, and biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) as dianhydride monomers were introduced to confirm that they were completely dissolved. The temperature was raised to 40° C. under a nitrogen atmosphere, and stirring was continued for 120 minutes while heating, and then a polyamic acid solution having a viscosity of 7,000 cP at 23° C. was prepared.

[0051] Subsequently, the temperature was raised to 80° C. under a nitrogen atmosphere, and stirring was additionally continued for 2 hours while heating, and then the temperature was cooled to 23° C. to prepare a polyimide precursor composition representing a viscosity of 5,100 cP.

[0052] The polyimide precursor composition was applied to a WIZUS Glass (Asahi Glass) support in the form of a thin film, and then heat-treated under an oxygen and nitrogen atmosphere of Table 1 below, while starting the temperature from about 110° C. and increasing it to 460° C., and subsequently peeled from the support to prepare a polyimide in the form of a film having an average thickness of about 15 to 17 μm, respectively.

Examples 2 to 5 and Comparative Examples 1 to 2

[0053] Polyimides were prepared in the same method as in Example 1, except that in Example 1, process conditions were each changed as shown in Table 1 below.

TABLE-US-00001 TABLE 1 Atmosphere Film Process highest (Nitrogen:oxygen) thickness temperature (Volume ratio) (μm) (° C.) Example 1 90:10 15.3 460 2 80:20 15.8 460 3 50:50 15.4 460 4 30:70 15.0 460 5 10:90 16.2 460 Comparative 1 100:0  15.3 460 Example 2  0:100 15.3 460

Experimental Example 1—CTE

[0054] TA's Thermomechanical Analyzer Q400 model was used, and a polyimide film was cut into 2 mm wide and 10 mm long, and then after the temperature was raised from room temperature to 500° C. at a rate of 10° C./min while applying a tension of 0.05 N under a nitrogen atmosphere, the gradient of the section from 100° C. to 350° C. was measured while cooling at a rate of 10° C./min again. The CTE was first measured in the elevating temperature section from 100° C. to 350° C., and subsequently the CTE was measured in the reducing temperature section from 350° C. to 100° C.

Experimental Example 2—Glass Transition Temperature

[0055] As for the glass transition temperature, the loss elastic modulus and storage elastic modulus of each polyimide resin were obtained using TMA, and the inflection point in their tangent graphs was measured as the glass transition temperature.

Experimental Example 3—Adhesion Force

[0056] Adhesion force was measured using the method set forth in ASTM D 3359. Specifically, the polyimide films prepared in Examples and Comparative Examples were each attached to a glass substrate to have a width of 10 mm, and the adhesion force was measured while peeling it at a peel rate of 20 mm/min and a peel angle of 180°. The unit of adhesion force is N/cm.

Experimental Example 4—Light Transmittance

[0057] With respect to the polyimide film prepared above, using a UV-Vis spectrometer, the light transmittance was measured in a wavelength region of 380 nm to 780 nm, and the average value was calculated, and also the light transmittance at 550 nm was measured.

TABLE-US-00002 TABLE 2 Glass Light CTE (ppm/° C.) transition Adhesion transmittance (%) Elevating Reducing temperature force Average temperature temperature (° C.) (N/cm) value 550 nm Example 1 4.5 4.7 410 0.54 60.3 62.9 2 9.2 8.3 396 0.35 56.2 57 3 15.0 13.4 379 0.2 54.3 55.8 4 14.3 11.3 381 0.2 52 54.2 5 14.2 12.2 380 0.1 49.7 51.3 Comparative 1 18.9 17 357 0.05 61.4 64.2 Example 2 25 30 338 0.01 48.5 54