PHOTOSENSITIVE POLYIMIDE RESIN FOR ULTRAVIOLET (UV) CURING-BASED 3D PRINTING AND PREPARATION METHOD THEREOF

Abstract

A photosensitive polyimide resin for ultraviolet curing-based three-dimensional printing, which is prepared from 40-60 parts by weight of an active group-containing polyimide resin; 20-50 parts by weight of an organic activator; and 2-5 parts by weight of a photoinitiator. This application further provides a method for preparing the photosensitive polyimide resin.

Claims

1. A photosensitive polyimide resin for ultraviolet (UV) curing-based three-dimensional (3D) printing, wherein raw materials for preparation of the photosensitive polyimide resin comprise: 40-60 parts by weight of an active group-containing polyimide resin; 20-50 parts by weight of an organic activator; and 2-5 parts by weight of a photoinitiator; wherein the organic activator comprises methyl methacrylate (MMA) and 1-vinyl-2-pyrrolidone (NVP).

2. The photosensitive polyimide resin of claim 1, wherein raw materials for preparation of the active group-containing polyimide resin comprises: 5-15 parts by weight of 2-(4-aminophenyl)-5-aminobenzimidazole (APBIA); 10-20 parts by weight of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA); 0.03-0.05 part by weight of triethylamine (TEA); 1.71-5.12 parts by weight of glycidyl methacrylate (GMA); 0.12-0.36 part by weight of a polymerization inhibitor; and a solvent.

3. The photosensitive polyimide resin of claim 2, wherein the polymerization inhibitor is selected from the group consisting of hydroquinone, 2-tert-butylhydroquinone (TBHQ), 2,5-di-tert-butylhydroquinone (DBHQ), and a combination thereof.

4. The photosensitive polyimide resin of claim 2, wherein the solvent is selected from the group consisting of N-methylpyrrolidone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide, and a combination thereof.

5. A method for preparing the photosensitive polyimide resin of claim 1, comprising: adding the active group-containing polyimide resin, the organic activator and the photoinitiator in a ball grinding mill followed by grinding in the dark for uniform mixing to obtain the photosensitive polyimide resin.

6. The method of claim 5, wherein the active group-containing polyimide resin is prepared through steps of: adding APBIA into a solvent to obtain a first mixture; adding BTDA into the first mixture for reaction to obtain a second mixture; and adding TEA, GMA, and a polymerization inhibitor into the second mixture for condensation reaction to obtain the active group-containing polyimide resin.

7. The method of claim 6, wherein the step of “adding BTDA into the first mixture for reaction to obtain a second mixture” comprises: adding BTDA into the first mixture in an ice-water bath followed by stirring in an inert gas atmosphere, reaction in a hydrothermal reactor, reaction at a low temperature, and reaction in a heating system, so as to obtain the second mixture. 8. The method of claim 7, wherein the heating system is successively set at 120° C. for 2 h, 160° C. for 2 h, and 200° C. for 12 h.

9. The method of claim 7, wherein the “reaction at a low temperature ” is carried out at 4° C. for 24 h.

10. The method of claim 6, wherein the condensation reaction is carried out at 100° C. for 5 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 schematically shows a printed sample created using a photosensitive polyimide resin obtained in Example 1 of the present disclosure;

[0037] FIG. 2 shows a standard strip for tensile test;

[0038] FIG. 3 shows a strip for tensile test which is printed using the photosensitive polyimide resin obtained in Example 1 of the present disclosure;

[0039] FIG. 4 shows a thermogravimetric analysis (TGA) curve of a sample printed using the photosensitive polyimide resin obtained in Example 1 of the present disclosure;

[0040] FIG. 5 shows a TGA curve of a sample printed using the photosensitive polyimide resin obtained in Example 3 of the present disclosure;

[0041] FIG. 6a is a perspective of a printed impact strip;

[0042] FIG. 6b is a top view of the printed impact strip;

[0043] FIG. 7 shows a thickness of the printed impact strip; and

[0044] FIG. 8 shows a width of the printed impact strip.

DETAILED DESCRIPTION OF EMBODIMENTS

[0045] In order to illustrate the object, technical solutions and advantages of the disclosure more clearly and completely, the disclosure will be further described below in conjunction with embodiments and drawings.

[0046] Unless otherwise expressly specified and defined, the test methods used in the following embodiments are conventional methods, and the materials, and reagents are commercially-available.

[0047] Raw materials for preparing a photosensitive polyimide resin include: [0048] 40-60 parts by weight of an active group-containing polyimide resin; [0049] 20-50 parts by weight of an organic activator; and [0050] 2-5 parts by weight of a photoinitiator.

[0051] In an embodiment, the active group-containing polyimide resin includes an acryloyl active group.

[0052] In an embodiment, raw materials for preparation of the active group-containing polyimide resin includes: [0053] 5-15 parts by weight of 2-(4-aminophenyl)-5-aminobenzimidazole (APBIA); [0054] 10-20 parts by weight of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA); [0055] 0.03-0.05 part by weight of triethylamine (TEA); [0056] 1.71-5.12 parts by weight of glycidyl methacrylate (GMA); [0057] 0.12-0.36 part by weight of a polymerization inhibitor; and a solvent.

[0058] Specifically, APBIA reacts with BTDA to form an imidized structure. APBIA contains benzimidazole heterocyclic units, which can improve the mechanical properties of the material after curing.

[0059] More specifically, glycidyl methacrylate (GMA) is a photosensitive unit that provides the active site for subsequent light curing.

[0060] In an embodiment, the active group-containing polyimide resin is prepared through the following steps.

[0061] The APBIA is added to the solvent to obtain a first mixture.

[0062] BTDA is added to the first mixture for reaction to obtain a second mixture.

[0063] The TEA, GMA, and polymerization inhibitor are added to the second mixture for condensation reaction to obtain the active group-containing polyimide resin.

[0064] In an embodiment, the step of “adding BTDA into the first mixture for reaction to obtain a second mixture” includes: adding BTDA into the first mixture in an ice-water bath followed by stirring in an inert gas atmosphere, and reaction in a hydrothermal reactor, reaction at a low temperature environment, and reaction in a heating system, to obtain the second mixture.

[0065] In an embodiment, the “reaction at a low temperature environment” is carried out at 4° C. for 24 h.

[0066] In an embodiment, the heating system is successively set at 120° C. for 2 h, at 160° C. for 2 h, and at 200° C. for 12 h. Specifically, the imidization of polyimide is carried out at 200° C. But directly rising to 200° C. is easy to cause side reactions. Therefore, the reaction temperature needs to be gradually risen, for example, can start from 80° C., be increased at 20° C./h, and finally keep at 200° C. for more than 10 h.

[0067] In an embodiment, the polymerization inhibitor is selected from the group consisting of hydroquinone, 2-tert-butylhydroquinone (TBHQ), and 2,5-di-tert-butylhydroquinone (DBHQ), and a mixture thereof.

[0068] In an embodiment, the solvent is selected from the group consisting of N-methylpyrrolidone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide, and a combination thereof.

[0069] In an embodiment, the organic activator includes methyl methacrylate (MMA) and 1-vinyl-2-pyrrolidone. Specifically, MMA has high activity and is easy to polymerize when irradiated or heated by ultraviolet light. MMA as the second active photosensitive unit is beneficial to improve the efficiency of UV curing. In an embodiment, the photosensitive polyimide resin is applied to the SLA or DLP printer.

[0070] The disclosure provides a method for preparing the photosensitive polyimide resin, including: adding the active group-containing polyimide resin, the organic activator, and the photoinitiator in a ball grinding mill followed by grinding in the dark place for uniform mixing to obtain the photosensitive polyimide resin.

[0071] The organic activator includes methyl methacrylate and 1-vinyl-2-pyrrolidone.

[0072] The raw material compositions of Examples 1-4 were shown in Table 1.

[0073] The active group-containing polyimide resin was prepared by the following steps.

[0074] 10.76 g (48 mmol) of APBIA was added into 80 mL of NMP followed by stirring in N.sub.2 atmosphere to disperse APBIA evenly, so as to obtain the first mixture.

[0075] 15.79 g (49 mmol) of BTDA was added to the first mixture in an ice-water bath followed by stirring in the N.sub.2 atmosphere, pouring in a hydrothermal reactor (200 mL), filling N.sub.2 into the hydrothermal reactor, and putting in the refrigerator for reaction at about 4° C. for 24 h, so as to obtain the second mixture. The hydrothermal reactor was removed from the refrigerator to room temperature. Then the hydrothermal reactor was placed in the heating system for reaction. Specifically, the heating system is successively set at 120° C. for 2 h, 160° C. for 2 h, and at 200° C. for 12 h, so as to obtain polyimide solution.

[0076] The polyimide solution was cooled to room temperature. 40 mg of TEA, 4.12 g of GMA, and 200 mg of hydroquinone were added into the polyimide solution in sequence, stirred well, and reacted at about 100° C. for 5 h while the hydrothermal reactor was covered, so as to obtain the reaction solution. Then the reaction solution was cooled to room temperature, placed in water for precipitation, filtrated by a vacuum pump, cleaned 3 times, and dried in an oven 50° C. for 12 h, to obtain light-yellow powder A, which was active group-containing polyimide resin. The washing water was deionized water, and the dosage of water was 100 mL/time.

[0077] The photosensitive polyimide resin was prepared through the following steps.

[0078] The active group-containing polyimide resin A, the photoinitiator (Irgacure 819), the organic activator MMA, and the solvent-activator NVP were placed in the ball grinding mill followed by grinding in the dark place for 2 h for uniform mixing to obtain the homogeneous viscous transparent photosensitive polyimide resin.

[0079] The photosensitive polyimide resins prepared in Examples 1-4 were placed in the storage tank of the ordinary commercial SLA printer. The printing conditions were set, and the finished products were printed. The printed products were rinsed off the adhering resin with water, wiped dry, and placed in a UV curing box to continue curing for 2 h to obtain the final samples.

[0080] The printing conditions were as follows: [0081] Size (mm) 80.00*5.00*10.00; [0082] Volume (ml) 4.00; [0083] Number of triangular polygons 12; and [0084] Number of vertices 36.

[0085] A photograph of the printed sample created using the photosensitive polyimide resin obtained in Example 1 was shown in FIG. 1.

TABLE-US-00001 TABLE 1 Raw material composition of Examples 1~4 (by weight) Active group-containing polyimide resin Photoinitiator MMA NVP Example 1 40 parts 2 parts 20 parts 20 parts Example 2 40 parts 5 parts 10 parts 30 parts Example 3 60 parts 2 parts 20 parts 20 parts Example 4 60 parts 5 parts 10 parts 30 parts

[0086] Test results of viscosity and density of photosensitive polyimide resin prepared in

[0087] Examples 1-4 were shown in Table 2.

TABLE-US-00002 TABLE 2 Test results of viscosity and density of samples (25° C.) Viscosity/cps Density/g .Math. cm.sup.−3 Example 1 262 1.13 Example 2 256 1.23 Example 3 278 1.07 Example 4 271 1.10

[0088] The tensile strength and volume shrinkage of the sample strips printed using the photosensitive polyimide resin prepared in Examples 1˜4 was tested. FIG. 2 showed a standard strip for tensile test (parameters (expressed by mm) were listed in Table 3). The sample strip for tensile test printed using the photosensitive polyimide resin obtained in Example 1 was shown in FIG. 3, and the test results of tensile strength and volume shrinkage were shown in Table 4.

TABLE-US-00003 TABLE 3 Parameters of the standard strip for tensile test Symbol Name Size Tolerance L Overall length 115 — (minimum) H Distance between 80 ±5 fixtures C Length of middle 33 ±2 parallel section C.sub.0 Gauge length 25 ±1 (or valid part) W End width 25 ±1 d Thickness ≤2 — b Width of middle 5 ±0.4 parallel section Ra Small radius 14 ±1 Rb Large radius 25 ±2

TABLE-US-00004 TABLE 4 Test results for tensile strength and volume shrinkage (25° C.) Tensile strength/MPa Volume shrinkage/% Example 1 129 8.9 Example 2 109 9.1 Example 3 175 8.5 Example 4 164 7.9

[0089] It could be seen from Table 4 that through testing the tensile strength and heat resistance of the sample strips printed using the photosensitive polyimide resin prepared in Examples 1˜4, it was proved that the strength and heat resistance of the samples after SLA printing and light curing were not different from the heat-cured polyimide on the market. In other words, the samples in this disclosure could meet the standard of polyimide on the market.

[0090] In addition, it was also verified that polyimide, prepared using acrylic acid, styrene, polyethylene glycol diacrylate, and lauryl methacrylate as reactive diluents, could not be used in light-curing 3D printers, could not be printed and molded, and was sludge-like.

[0091] FIG. 4 showed a thermogravimetric analysis (TGA) curve of a sample printed using the photosensitive polyimide resin obtained in Example 1. FIG. 5 showed a TGA curve of a sample printed using the photosensitive polyimide resin obtained in Example 3. As could be seen from FIGS. 4 and 5, the printed samples using the photosensitive polyimide resin obtained in Examples 1 and 3 have good heat resistance and can withstand high temperature of more than 410° C.

[0092] As shown in FIGS. 6a and ab, the photosensitive polyimide resin prepared in Example 1 was placed in a small square desktop-grade light-curing printer (dazzle-3D) to print impact strips. The impact strips were set in a center of the printing plane. Six impact strips were arranged longitudinally. The narrow surface was perpendicular to the printing surface. The printing conditions (thickness, width, and length) were 5.00 mm, 7.30 mm, and 10.00 mm. The number of printing layers was 100. The consumable mode was “transparent - advanced”. The thickness and width of the printed impact strips was tested, as shown in FIGS. 7 and 8.

[0093] The readings in FIG. 7 and FIG. 8 were as follows: FIG. 7: 5.05 mm, and FIG. 8: 7.32 mm.

[0094] It should be noted that described above are merely preferred embodiments of the disclosure, which are not intended to limit the disclosure. It should be understood that any modifications and replacements made by those skilled in the art without departing from the spirit of the disclosure should fall within the scope of the disclosure defined by the appended claims.