Preparation method of hyperbranched polyurethane acrylate resin and 3D printing photosensitive resin composition

Abstract

The invention belongs to the field of photocuring 3D printing materials, and particularly relates to a preparation method of hyperbranched polyurethane acrylate resin and a 3D printing photosensitive resin composition. The photosensitive resin is used as hyperbranched polyurethane acrylate, dihydric alcohol with the low molecular weight Mn of 200-400 is used as a main component for pre-branching, dihydric alcohol with the high molecular weight Mn of 1000-2000 is used for chain extension, and finally hydroxyl acrylate is used for terminating to prepare the hyperbranched polyurethane acrylate. Compared with a traditional micromolecule branching mode, branching through the low-molecular-weight dihydric alcohol is easier to control and not prone to gelling, a hyperbranched polymer with the large molecular weight and the high branching degree is easily obtained, and therefore the purposes of improving the toughness of resin and reducing the curing shrinkage rate are achieved. The purpose of regulating and controlling the thermal stability of a cured product is achieved by selecting dihydric alcohols with different thermal degradation temperatures.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology for photopolymer 3D printing, specifically relating to the preparation method of hyperbranched polyurethane acrylate resin and 3D printing photosensitive resin composition. Background Technology

[0002] With the rapid development of 3D printing technology, the demand for high-performance materials is increasing. Traditional resin materials suffer from insufficient hardness, poor weather resistance, and low molding accuracy in 3D printing. Hyperbranched polyurethane acrylate resins have become a research hotspot due to their unique structure and properties. The hyperbranched structure endows the resin with good solubility, low viscosity, and high reactivity. In 3D printing, this resin can achieve rapid curing, high-precision molding, and excellent mechanical properties and chemical resistance. Currently, although there has been some research on polyurethane acrylate resins, the preparation methods of hyperbranched polyurethane acrylate resins and their applications in 3D printing still need further exploration and optimization. The preparation process of traditional hyperbranched polyurethanes is cumbersome, requiring a low-temperature initial reaction, and they are prone to gelation during subsequent heating and self-polymerization, resulting in excessively high production costs. In addition, the branched core is too singular and difficult to modify, such as the common isophorone diisocyanate (IPDI) and diethanolamine (DEA).

[0003] In conclusion, in response to the ever-increasing technical requirements and market demands of 3D printing, it is necessary to develop various new methods for preparing hyperbranched polyurethane acrylate resins and their applications in 3D printing. Summary of the Invention

[0004] To address the aforementioned shortcomings in the field, a 3D printing photosensitive resin composition that is not prone to gelling and is easy to clean after printing has been invented.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On one hand, this invention provides a method for preparing hyperbranched polyurethane acrylate resin: 1. The raw materials include diisocyanate, diol A, trimethylolpropane, diol B, and monohydroxy acrylate, wherein: The molecular weight of the diol A is Mn = 200~400; The molecular weight of the diol B is Mn = 1000~2000; Its preparation method includes the following steps: The diol A was capped with the diisocyanate under the catalysis of dibutyltin dilaurate, and then branched and extended with the trimethylolpropane to form an isocyanate-capped hyperbranched polyurethane prepolymer (HPP). The diisocyanate was reacted with the monohydroxy acrylate to prepare an intermediate with an isocyanate group at one end and an acrylate group at the other end. Then, the diol B was added and reacted to form a semi-addition product (SAP) with a hydroxyl group at one end and an acrylate group at the other end. The hyperbranched polyurethane prepolymer (HPP) is reacted with the acrylate-based semi-addition product (SAP) to obtain the hyperbranched polyurethane acrylate resin.

[0006] As a preferred embodiment of the present invention, the diol A and the diol B are each independently selected from any one of polyethylene glycol, polypropylene glycol, polytetrahydrofuran ether glycol, polycarbonate diol, and polycaprolactone diol.

[0007] As a preferred embodiment of the present invention, the molar ratio of the diisocyanate, diol A, trimethylolpropane, diol B and monohydroxy acrylate is 7~9:2.5~3.5:1~1.5:1.5~3:1.5~3.

[0008] As a preferred technical solution of the present invention, isophorone diisocyanate (IPDI), dicycloethylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), trimethylhexamethylene diisocyanate (2,2,4- and 2,4,4- mixture), and trimethylhexamethylene diisocyanate (2,2,4-, 2,4,4- mixture).

[0009] As a preferred embodiment of the present invention, the monohydroxy acrylate is selected from: hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 3-(acryloyloxy)-2-hydroxypropyl methacrylate, polyethylene glycol monomaleate, and 2-[2-[2-(2-hydroxyethoxy)ethoxy]ethoxy]ethyl acrylate.

[0010] As a preferred embodiment of the present invention, the intermediate having an isocyanate group at one end and an acrylate group at the other end has approximately the same molar number as the diol B.

[0011] On the other hand, the present invention provides a method for preparing a 3D printing photosensitive resin composition, which is obtained from the above-mentioned hyperbranched polyurethane acrylate resin. The steps include: placing the hyperbranched polyurethane acrylate resin, acrylate monomer, photoinitiator and additives in a reaction vessel according to the weight parts, stirring and mixing evenly, then evacuating the vacuum to remove air bubbles, and filling and sealing the obtained composition.

[0012] As a preferred embodiment of the present invention, the acrylate monomer is selected from propionyl oxynepentyl glycol diacrylate, propionyl oxyglycerol triacrylate, ethoxytrimethylolpropane triacrylate, ethoxypentaerythritol tetraacrylate, ethoxyethoxyethyl acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and dipropylene glycol di(meth)acrylate.

[0013] As a preferred embodiment of the present invention, the photoinitiator is selected from 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0014] As a preferred embodiment of the present invention, the additives include at least one of polymerization inhibitors, defoamers, leveling agents, and organic pigments.

[0015] By adopting the above technical solution, the beneficial effects of the present invention are as follows: Compared to traditional small-molecule branching methods, this invention utilizes diols with varying molecular weights for branching, which is easier to control, less prone to gelation, and more likely to yield hyperbranched polymers with larger molecular weights and higher degrees of branching. This improves resin toughness and reduces curing shrinkage. By selecting diols with different thermal degradation temperatures in a balanced mix, the thermal stability of the cured product can be controlled. Furthermore, choosing diols with good ethanol compatibility improves the resin-ethanol relationship, meeting the post-cleaning requirements of photosensitive resins for SLA, DLP, or LCD 3D printers. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart illustrating the synthesis of hyperbranched polyurethane acrylate resin in Example 1 of the present invention; Figure 2 This is the TG curve of the 3D printing photosensitive resin composition printed sample in Example 1 of the present invention. Detailed Implementation

[0017] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0018] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the invention. For example, as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0019] To achieve the above objectives, this invention proposes a hyperbranched polyurethane acrylate resin and prepares a 3D printing photosensitive resin composition. This composition utilizes a hyperbranched polyurethane acrylate resin with numerous photosensitive groups at its ends, exhibiting high reactivity and enabling rapid photocuring. Based on the hyperbranched structure with initially short branches followed by longer branches and the control of flexible segments, the curing shrinkage, flexibility, and thermal degradation stability of the cured product can be controlled. This preparation method is simple, environmentally friendly, and energy-saving, making it suitable for the field of photocurable 3D printing.

[0020] Example 1 The synthesis flow chart of hyperbranched polyurethane acrylate resin is attached. Figure 1 As shown in Table 1, the raw material formula is as follows: A1. Weigh 280 parts by weight of isophorone diisocyanate (IPDI) and add it to a flask. Heat in an oil bath at 70°C and stir mechanically. Add 126 parts by weight of polypropylene glycol with a molecular weight of Mn200 and 1 part by weight of dibutyltin dilaurate (DBTL) as catalysts. After the end-capping reaction is carried out for 2 hours, add 38 parts by weight of trimethylolpropane (TMP) and carry out the branching reaction for 3 hours to obtain a hyperbranched polyurethane prepolymer (HPP) with isocyanate groups at the end. A2. Add 313 parts by weight of IPDI to a flask, heat in an oil bath at 70°C and stir magnetically. Add 164 parts by weight of hydroxyethyl acrylate (HEA) and 1.4 parts by weight of DBTL dropwise. After reacting for 2 hours, add 1410 parts by weight of polypropylene glycol with a molecular weight of Mn1000 dropwise and react for 3 hours to obtain a semi-addition product (SAP) with a hydroxyl group at one end and an acrylate group at the other end. Seal and store for later use. A3. Weigh 562 parts by weight of SAP and add it to the prepared HPP, and add 3 parts by weight of DBTL. React at a constant temperature of 70℃ for 4 hours. The characteristic peak of the NCO group disappears after infrared testing, and the hyperbranched polyurethane acrylate resin is obtained.

[0021] Furthermore, the preparation of the 3D printing photosensitive resin composition using the above-mentioned hyperbranched polyurethane acrylate resin includes the following steps: B1. Weigh 50 parts by weight of the synthesized hyperbranched polyurethane acrylate resin, 20 parts by weight of diethylene glycol di(meth)acrylate, 2% by weight of photoinitiator, and 0.4% by weight of additives and add them to the reactor. B2. Mix thoroughly by mechanical stirring at a speed of 800~1500 r / min for 0.5 h, then vacuum to remove air bubbles for 15 min. B3. Fill and seal the product.

[0022] The preparation methods described above were followed for Examples 2 to 10, with adjustments made to the components between each example, while all other conditions remained the same. Example

[0023] Ingredients (parts by weight): Isophorone diisocyanate IPDI: 280; Polypropylene glycol Mn 200: 126; Polytetrahydrofuran ether diol: Mn = 1500: 1420; Trimethylolpropane (TMP): 38; Hydroxypropyl acrylate: 324.

[0024] Example 3 Ingredients (parts by weight): Bicycloethylmethane diisocyanate HMDI: 260; Polytetrahydrofuran ether diol Mn = 300:250; Polycaprolactone diol: Mn = 1500:1600; Trimethylolpropane (TMP): 38; Hydroxypropyl acrylate: 324.

[0025] Example 4 Ingredients (parts by weight): Hexamethylene diisocyanate (HDI): 265; Polyethylene glycol Mn = 400:150; Polycaprolactone diol: Mn = 2000: 1600; Trimethylolpropane (TMP): 38; Hydroxypropyl acrylate: 324.

[0026] Example 5 Ingredients (parts by weight): Lysine diisocyanate LDI: 270; Polyethylene glycol Mn = 300:150; Polycaprolactone diol: Mn = 2000: 1600; Trimethylolpropane (TMP): 38; Hydroxyethyl methacrylate: 297.

[0027] Example 6 Ingredients (parts by weight): Trimethylhexamethylene diisocyanate (2,2,4- and 2,4,4- mixture): 260; Polycaprolactone diol Mn = 300:150; Polyethylene glycol Mn = 1800:1600; Trimethylolpropane (TMP): 38; Hydroxypropyl methacrylate: 315.

[0028] Example 7 Ingredients (parts by weight): Trimethylhexamethylene diisocyanate (2,2,4-,2,4,4- mixture): 275; Polypropylene glycol Mn = 250:150; Polycarbonate diol Mn = 1500:1600; Trimethylolpropane (TMP): 38; Hydroxyethyl acrylate: 320 Example

[0029] Ingredients (parts by weight): Bicycloethylmethane diisocyanate (HMDI): 283; Polycarbonate diol Mn = 350:150; Polypropylene glycol Mn = 1600:1600; Trimethylolpropane (TMP): 38; 3-(acryloyloxy)-2-hydroxypropyl methacrylate: 304. Example

[0030] Ingredients (parts by weight): Hexamethylene diisocyanate (HDI): 265; Polytetrahydrofuran ether diol Mn = 250:160; Polypropylene glycol Mn = 1800:1500; Trimethylolpropane (TMP): 38; 2-[2-[2-(2-hydroxyethoxy)ethoxy]ethoxy]ethyl acrylate: 278.

[0031] Example 10 Ingredients (parts by weight): Isophorone diisocyanate (IPDI): 280; Polycaprolactone diol Mn = 350:160; Polycaprolactone diol Mn = 2000:1500; Trimethylolpropane (TMP): 38; Polyethylene glycol monomaleate: 260. To verify the beneficial effects of the present invention, the following comparative examples were provided. Comparative Example 1 The difference between this comparison and Example 1 is that the branching monomer trimethylolpropane is replaced with the chain extender 1,3-propanediol, while the other conditions are the same.

[0032] Comparative Example 2 This comparative example prepared a 3D printing photosensitive resin composition. The difference between this comparative example and Example 1 is that the hyperbranched polyurethane acrylate resin is commercial product 1, while the other conditions are the same.

[0033] Comparative Example 3 This comparative example prepared a 3D printing photosensitive resin composition. The difference between this comparative example and Example 1 is that the hyperbranched polyurethane acrylate resin is commercial product 2, while the other conditions are the same.

[0034] Experiments showed that Examples 1 to 10 had similar performance characteristics. Examples 1 to 4 and Comparative Examples 1 to 3 were then selected for performance testing. Samples were taken and their viscosity was measured using a viscometer. Test specimens were then printed using a photopolymer 3D printer (Sonic Mini 8K S), and the mechanical properties, surface hardness, viscosity, and thermal stability of the specimens were tested sequentially. The test results are as follows:

[0035] Therefore, the performance of the above embodiments is superior to that of the comparative examples. The branching process is easier to control, avoiding gelation and simplifying the preparation process. Furthermore, it can obtain hyperbranched polymers with high molecular weight and high branching degree, thus optimizing resin performance. Moreover, it can specifically regulate the thermal stability of the cured product, broadening the application scenarios of the material.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for the preparation of a hyperbranched polyurethane acrylate resin, characterized in that, The raw materials include diisocyanate, diol A, trimethylolpropane, diol B and monohydroxy acrylate, wherein: The molecular weight Mn of the diol A is 200-400; The molecular weight Mn of the diol B is 1000-2000; The preparation method comprises the following steps: The diol A is capped with the diisocyanate under the catalysis of dibutyltin dilaurate, and then branched chain extension is performed with the trimethylolpropane to form an isocyanate group capped hyperbranched polyurethane prepolymer (HPP); The diisocyanate and the monohydroxy acrylate are reacted to obtain an intermediate with one end being an isocyanate group and the other end being an acrylate group, and then the diol B is added to form a semi-addition product (SAP) with one end being a hydroxyl group and the other end being an acrylate group; The hyperbranched polyurethane prepolymer (HPP) and the semi-addition product (SAP) with the acrylate group are reacted to obtain the hyperbranched polyurethane acrylate resin.

2. The production method according to claim 1, characterized by, The diol A and the diol B are independently selected from any one of polyethylene glycol, polypropylene glycol, polytetrahydrofuran ether diol, polycarbonate diol and polycaprolactone diol.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the diisocyanate, diol A, trimethylolpropane, diol B and monohydroxy acrylate is 7-9:2.5-3.5:1-1.5:1.5-3:1.5-3.

4. The production method according to claim 1, characterized by, The diisocyanate is selected from isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), trimethylhexane diisocyanate (2,2,4- and 2,4,4-mixture), trimethylhexamethylene diisocyanate (2,2,4-, 2,4,4-mixture).

5. The method of claim 1, wherein, The monohydroxy acrylate is selected from hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 3-(acryloyloxy)-2-hydroxypropyl methacrylate, polyethylene glycol monomaleate and 2-[2-[2-(2-hydroxyethoxy)ethoxy]ethoxy]ethyl acrylate.

6. The method of claim 1, wherein, The molar number of the intermediate with one end being an isocyanate group and the other end being an acrylate group is approximately equal to that of the diol B.

7. A method for preparing a 3D printing photosensitive resin composition from the hyperbranched polyurethane acrylate resin according to any one of claims 1 to 6, characterized by the steps of It comprises: The hyperbranched polyurethane acrylate resin, acrylate monomer, photoinitiator and auxiliary agent are placed in a reaction kettle in parts by weight, stirred and mixed uniformly, vacuumed to exhaust air bubbles, and the obtained composition is filled and stored.

8. The preparation method according to claim 7, characterized in that, The acrylate monomer is selected from propoxylated neopentyl glycol dipropyl acrylate, propoxylated glycerol triacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, acrylate ethoxyethoxyethyl ester, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate and propylene glycol di(meth)acrylate.

9. The preparation method according to claim 7, characterized in that, The photoinitiator is selected from the group consisting of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

10. The preparation method according to claim 7, characterized in that, The auxiliary agent includes at least one of polymerization inhibitor, defoaming agent, leveling agent, organic pigment.

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