A high-toughness photosensitive resin composition and a method for preparing the same

Abstract

This invention discloses a high-toughness photosensitive resin composition and its preparation method. The high-toughness photosensitive resin composition comprises, by weight, 52-58 parts of epoxy resin oligomer; 22-28 parts of acrylate oligomer; 4-6 parts of polyurethane acrylate; 0.3-0.4 parts of DOQDS with surface-grafted acrylate groups; 1.5-2.5 parts of surface-modified nano-silica; 0.6-0.8 parts of fumed silica; 3.4-4.5 parts of core-shell toughened epoxy resin; 6.5-7.5 parts of photoinitiator; 6-9 parts of reactive diluent; and 0.1-0.2 parts of imidazole catalyst. In this application, the GOQDs in the photosensitive resin composition are embedded in the epoxy resin backbone through chemical bonding rather than physical mixing. After the photosensitive resin is cross-linked, the flexible core layer of the core-shell toughening resin can improve the network's extensibility through chain segment slippage. Under stress, it assists the network in buffering stress and promoting chain segment movement. The GOQDs are dispersed in the cross-linked network as "reinforcing points," enhancing the network's rigidity and inhibiting chain segment movement. The GOQDs can work synergistically with the core-shell toughening resin to achieve the technical effect of reinforcement and toughening.

Description

Technical Field

[0001] This application relates to organic polymer compounds; their preparation or chemical processing; compositions based thereon, and specifically to a high-toughness photosensitive resin composition and its preparation method. Background Technology

[0002] 3D printing is a computer-aided, layer-by-layer manufacturing process. Among 3D printing technologies, stereolithography (SLA) is the most common. It mainly uses laser irradiation to cause photosensitive resin to undergo radiation polymerization, forming cross-linked polymers and producing solid materials.

[0003] Existing SLA photosensitive resins generally suffer from problems such as insufficient toughness. The invention patent document with announcement number CN114805702B describes an SLA photosensitive resin. This SLA high-toughness photosensitive resin performs outstandingly in terms of toughness optimization and hardness. However, the excessively high impact strength of this SLA photosensitive resin leads to a decrease in tensile strength. For example, the tensile strength of Example 2, which has the highest impact strength of 137 J / m as described in the above patent document, is only 22 MPa, while the impact strength of Example 5, which has the highest tensile strength of 46 MPa, drops to 83 J / m. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a high-toughness photosensitive resin composition that synergistically improves elongation at break and impact resistance, the technical solution of which includes:

[0005] A high-toughness photosensitive resin composition, comprising, by weight parts:

[0006] 52-58 parts of epoxy resin oligomer;

[0007] 22-28 parts of acrylate oligomer;

[0008] 4-6 parts of polyurethane acrylate;

[0009] 0.3-0.4 parts of DOQDS with surface-grafted acrylate groups.

[0010] 1.5-2.5 parts of surface-modified nano-silica;

[0011] Fumed silica 0.6-0.8 parts;

[0012] 3.4-4.5 parts of core-shell toughened epoxy resin;

[0013] Photoinitiator 6.5-7.5 parts;

[0014] 6-9 parts reactive diluent;

[0015] 0.1-0.2 parts of imidazole catalyst.

[0016] One embodiment of the present invention addresses the technical problem by employing the following technical solution: The preparation method of the DOQDS grafted with acrylate groups includes: taking 10-50 mL of DOQDs aqueous dispersion with a concentration of 1-5 mg / mL and stirring in a water bath at 50℃-70℃; adding a mixture of GMA and triethylamine dropwise, with GMA dosage of 250-500 mg and triethylamine dosage of 5-25 mg; maintaining the temperature for 4-6 hours; filtering the reaction solution through a 0.20-0.30 μm filter membrane; washing multiple times by centrifugation with anhydrous ethanol; and vacuum drying at 50℃-70℃ for 10-12 hours to obtain DOQDS with surface-grafted acrylate groups.

[0017] One embodiment of the present invention uses a technical solution to solve its technical problem: the polyurethane acrylate is a polyether-type polyurethane acrylate.

[0018] One embodiment of the present invention uses a technical solution to solve its technical problem: the grade of polyether-type polyurethane acrylate is CN991.

[0019] One embodiment of the present invention uses a technical solution to solve its technical problem: the particle size of the surface-modified nano-silica is 20-50 nm.

[0020] One embodiment of the present invention uses the following technical solution to solve its technical problem: the surface-modified nano-silica is nano-silica modified with a silane coupling agent.

[0021] This application also provides a method for preparing the above-mentioned high-toughness photosensitive resin composition, comprising:

[0022] Step 1: GOQDs Pretreatment: Add epoxy resin oligomer to the reaction vessel, heat to 60℃, add GOQDS with surface-grafted acrylate groups, perform ultrasonic dispersion, add imidazole catalyst, heat to 80-90℃, mechanically stir the reaction for 0.5-1h, monitor viscosity in real time until the viscosity increases by 20%-25%, 910cm -1 After the peak intensity of the epoxy group decreases by 20%-25%, the temperature is lowered to 40-42℃;

[0023] Step 2: Keep the temperature at 40-42℃, add acrylate oligomer and polyurethane acrylate in sequence, and after stirring evenly, add surface-modified nano silica and fumed silica. Shear at high speed until evenly dispersed, then cool down to 25-30℃, add core-shell toughening resin and reactive diluent, and stir for 20-30 minutes to obtain a product with a viscosity of 5000-8000 mPa·s.

[0024] Step 4: After adding the photoinitiator under light-protected conditions and stirring until there is no particle agglomeration, vacuum degassing is performed to obtain the photosensitive resin composition.

[0025] One embodiment of the present invention adopts the following technical solution to solve its technical problem: In step 3, if the viscosity of the product is greater than 8000 mPa·s, 0.5-1 part of 1,6-hexanediol diacrylate is added, and stirring is continued until the viscosity of the product is 5000-8000 mPa·s.

[0026] In the preparation of the high-toughness photosensitive resin composition, step 2 of this application promotes and controls the ring-opening of oligomeric epoxy resin by using reaction temperature and imidazole catalyst. After the ring-opening reaction, the oligomeric epoxy resin forms ether or ester bonds with GOQDs. GOQDs form denser covalent bonds of ether and ester bonds with epoxy resin. The dense interfacial covalent bonds make it easier to disperse impact energy to the surrounding matrix and avoid local stress concentration. GOQDs are embedded in the epoxy resin skeleton through chemical bonding (rather than physical mixing). The high modulus and nano-size effect of GOQDs act as "reinforcing points" dispersed in the cross-linked network. Under stress, they can resist external deformation through their own deformation and absorb energy through interfacial slip, crack deflection, etc., reducing crack propagation.

[0027] Viscosity and 910 cm -1 Dual peak intensity monitoring controls the ring-opening reaction of oligomeric epoxy resin, avoiding excessive consumption of epoxy groups which would affect the epoxy group density of the epoxy resin and thus the density of the three-dimensional crosslinking network. After subsequent crosslinking, GOQDs are covalently embedded in the three-dimensional crosslinking network of the epoxy resin to form an "organic-inorganic hybrid material".

[0028] After crosslinking the photosensitive resin, the shell of the core-shell toughening resin is a polymer containing acrylate groups. Its chemical structure is combined with the main body of the crosslinking network through van der Waals forces and a small number of covalent bonds (shell double bonds participate in crosslinking), ensuring that the core layer can be uniformly dispersed in the network. This allows the flexible core of the core-shell toughening epoxy resin to be embedded in the crosslinking network. The flexible core layer can improve the network's ductility through chain segment slippage, and assist the network in buffering stress and promoting chain segment movement under stress. GOQDs are dispersed in the crosslinking network as "reinforcing points" to enhance network rigidity and inhibit chain segment movement. GOQDs can work synergistically with the core-shell toughening resin to achieve the technical effect of reinforcement and toughening, improving the tensile strength and fracture toughness of the photosensitive resin.

[0029] GOQDs have high thermal conductivity, and their inorganic properties inhibit the high-temperature decomposition of polymer chain segments, resulting in high thermal stability. Detailed Implementation

[0030] Unless otherwise stated, the terms used in this invention generally have the meanings commonly understood by those skilled in the art.

[0031] The present invention will now be described in further detail with reference to specific embodiments and data. It should be understood that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention in any way.

[0032] In the following embodiments, the various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, apparatus, instruments, equipment, etc., used in the following examples are commercially available.

[0033] In this application, the epoxy resin oligomer is a blend of DYD-128 and HE-2025, which has a high Tg, which is beneficial to improving the heat resistance of the photosensitive resin composition; the photoinitiator is TPO-L and 819, which has a fast curing speed.

[0034] The preparation method of DOQDS with surface-grafted acrylate groups includes: taking 10 mL of DOQDs aqueous dispersion with a concentration of 5 mg / mL and stirring in a 60℃ water bath, adding dropwise a mixture of glycidyl methacrylate and triethylamine (GMA 250 mg, triethylamine 5 mg), incubating the reaction for 5 h, filtering through a 0.22 μm filter membrane, centrifuging with anhydrous ethanol at 10000 rpm for 8 min, repeating the centrifugation and washing three times, and drying in a vacuum environment at 60℃ for 10 h to obtain DOQDS with grafted acrylate groups. In this example, the DOQDS with grafted acrylate groups has acrylate grafted on the surface and still has residual active hydroxyl groups. Infrared verification showed that the product was soluble in 1725 cm⁻¹. -1 An acrylate carbonyl peak is present at 3400 cm⁻¹. -1 The intensity of the hydroxyl peak at that location is 30% of the intensity of the hydroxyl peak in GOQDs.

[0035] Based on the content of this invention, Examples 1-3 and Comparative Examples of this application are proposed. The raw materials and weight parts used in Examples 1-3 and Comparative Examples are shown in Table 1.

[0036] Table 1

[0037]

[0038] The preparation methods of the photosensitive resin compositions in Examples 1-3 and Comparative Example 1 include:

[0039] Step 1, GOQDs Pretreatment: Heat the epoxy resin oligomer to 60℃, add DOQDS with surface-grafted acrylate groups, and ultrasonically disperse for 40 min.

[0040] Step 2: Add 2-methylimidazole, heat to 85℃, mechanically stir at 800 rpm, react for 45 minutes, monitoring viscosity and infrared spectrum in real time, until the viscosity increases to 20%-25% of the initial value, and 910 cm⁻¹ -1 The peak intensity of the epoxy group decreases by 20%-25%, and the temperature drops rapidly to 40℃;

[0041] Step 3: At 40°C, add acrylate oligomer and polyurethane acrylate in sequence. Stir at 1200 rpm for 15 min, then add surface-modified nano silica and fumed silica. Shear at 5000 rpm for 30 min to form a uniformly dispersed inorganic-organic hybrid system. Then cool down to 30°C, add core-shell toughening resin and reactive diluent, and stir for 20 min to finally obtain a product with a viscosity of 5000-8000 mPa·s.

[0042] Step 4: Add the photoinitiator under light-protected conditions, and continue stirring at 800 rpm for 15 minutes to ensure no particle agglomeration. Then, degas under vacuum for 15 minutes at -0.1 MPa and 30°C to remove bubbles and obtain the photosensitive resin composition.

[0043] Comparative examples of this application are provided, and the raw materials used in the comparative examples are shown in Table 2.

[0044] In Comparative Example 1, the photosensitive resin composition did not contain DOQDS with surface-grafted acrylate groups or imidazole catalysts. The preparation method of the photosensitive resin composition in Comparative Example 1 is as follows:

[0045] The epoxy resin oligomer was heated to 40°C, and acrylate oligomer and polyurethane acrylate were added sequentially. After stirring at 1200 rpm for 15 min, surface-modified nano silica and fumed silica were added. The mixture was then sheared at 5000 rpm for 30 min to form a uniformly dispersed inorganic-organic hybrid system. The temperature was then lowered to 30°C, and core-shell toughening resin and reactive diluent were added. The mixture was stirred for 20 min to finally obtain a product with a viscosity of 5000-8000 mPa·s.

[0046] Add the photoinitiator under light-protected conditions, and continue stirring at 800 rpm for 15 min to ensure no particle agglomeration. Then, degas under vacuum for 15 min at -0.1 MPa and 30°C to remove bubbles and obtain the photosensitive resin composition.

[0047] Table 2

[0048]

[0049] In Comparative Example 2, DOQDS without acrylate grafted groups were added to the photosensitive resin composition. The preparation method of the photosensitive resin composition in Comparative Example 2 is as follows:

[0050] The epoxy resin oligomer was heated to 60°C, and 10 mL of GOQDs aqueous dispersion with a concentration of 5 mg / mL was added. The mixture was then ultrasonically dispersed for 40 min.

[0051] The mixture was cooled to 40°C, and then acrylate oligomer and polyurethane acrylate were added sequentially. After stirring at 1200 rpm for 15 min, surface-modified nano silica and fumed silica were added. The mixture was then sheared at 5000 rpm for 30 min to form a uniformly dispersed inorganic-organic hybrid system. The mixture was then cooled to 30°C, and core-shell toughening resin and reactive diluent were added. The mixture was stirred for 20 min to finally obtain a product with a viscosity of 5000-8000 mPa·s.

[0052] Add the photoinitiator under light-protected conditions, and continue stirring at 800 rpm for 15 min to ensure no particle agglomeration. Then, degas under vacuum for 15 min at -0.1 MPa and 30°C to remove bubbles and obtain the photosensitive resin composition.

[0053] In Comparative Example 3, DOQDS with surface-grafted acrylate groups were added to the photosensitive resin composition. The preparation method of the photosensitive resin composition in Comparative Example 3 is as follows:

[0054] The epoxy resin oligomer was heated to 60°C, and DOQDS with surface-grafted acrylate groups was added. The mixture was then ultrasonically dispersed for 40 min.

[0055] The mixture was cooled to 40°C, and acrylate oligomer and polyurethane acrylate were added sequentially. After stirring at 1200 rpm for 15 min, surface-modified nano silica and fumed silica were added. The mixture was then sheared at 5000 rpm for 30 min to form a uniformly dispersed inorganic-organic hybrid system. The mixture was then cooled to 30°C, and core-shell toughening resin and reactive diluent were added. The mixture was stirred for 20 min to finally obtain a product with a viscosity of 5000-8000 mPa·s.

[0056] Add the photoinitiator under light-protected conditions, and continue stirring at 800 rpm for 15 min to ensure no particle agglomeration. Then, degas under vacuum for 15 min at -0.1 MPa and 30°C to remove bubbles and obtain the photosensitive resin composition.

[0057] In Comparative Example 4, the photosensitive resin composition contained DOQDS with surface-grafted acrylate groups, but no core-shell toughened epoxy resin was added. The preparation method of the photosensitive resin composition in Comparative Example 4 is as follows:

[0058] The epoxy resin oligomer was heated to 60°C, and DOQDS with surface-grafted acrylate groups was added. The mixture was ultrasonically dispersed for 40 min. 2-Methylimidazole was added, and the temperature was raised to 85°C. The mixture was mechanically stirred at 800 rpm for 45 min, with viscosity and infrared spectroscopy monitored in real time until the viscosity increased to 20%-25% of the initial value. (910 cm⁻¹) -1 The peak intensity of the epoxy group decreases by 20%-25%, and the temperature drops rapidly to 40℃;

[0059] At 40°C, acrylate oligomer and polyurethane acrylate were added sequentially. After stirring at 1200 rpm for 15 min, surface-modified nano silica and fumed silica were added. The mixture was then sheared at 5000 rpm for 30 min to form a uniformly dispersed inorganic-organic hybrid system. The temperature was then lowered to 30°C, an active diluent was added, and the mixture was stirred for 20 min to finally obtain a product with a viscosity of 5000-8000 mPa·s.

[0060] Add the photoinitiator under light-protected conditions, and continue stirring at 800 rpm for 15 min to ensure no particle agglomeration. Then, degas under vacuum for 15 min at -0.1 MPa and 30°C to remove bubbles and obtain the photosensitive resin composition.

[0061] The photosensitive resin compositions prepared in Examples 1-3 and Comparative Examples 1-4 were used to form films with a thickness of 50 micrometers. After being irradiated with ultraviolet light at a wavelength of 365 nm and a light intensity of 1000 mW / cm² for 30 seconds, the films were cut into test samples that met the specifications and various performance tests were performed. The test results are shown in Table 2.

[0062] Table 3

[0063]

[0064] The impact strength test references the standard GB / T 1843-2008; the tensile strength and elongation at break test reference the standard GB / T 1040.1-2018.

[0065] Of course, the present invention is not limited to the above-described embodiments. Those skilled in the art can make equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications and substitutions are all included within the scope defined by the claims of this application.

Claims

1. A high-toughness photosensitive resin composition, characterized in that, By weight, it includes: 52-58 parts of epoxy resin oligomer; 22-28 parts of acrylate oligomer; 4-6 parts of polyurethane acrylate; 0.3-0.4 parts of GOQDs with surface-grafted acrylate groups. 1.5-2.5 parts of surface-modified nano-silica; Fumed silica 0.6-0.8 parts; 3.4-4.5 parts of core-shell toughened epoxy resin EPX-125; Photoinitiator 6.5-7.5 parts; 6-9 parts reactive diluent; 0.1-0.2 parts of imidazole catalyst.

2. The high-toughness photosensitive resin composition according to claim 1, characterized in that, The preparation method of the GOQDs grafted with acrylate groups includes: taking 10-50 mL of GOQDs aqueous dispersion with a concentration of 1-5 mg / mL and stirring in a water bath at 50℃-70℃, adding dropwise a mixture of GMA and triethylamine, with GMA amounting to 250-500 mg and triethylamine amounting to 5-25 mg, keeping the reaction at this temperature for 4-6 h, filtering the reaction solution through a 0.20-0.30 μm filter membrane, washing it multiple times by centrifugation with anhydrous ethanol, and vacuum drying it at 50℃-70℃ for 10-12 h to obtain GOQDs with surface grafted acrylate groups.

3. The high-toughness photosensitive resin composition according to claim 1, characterized in that, The polyurethane acrylate is a polyether-type polyurethane acrylate.

4. The high-toughness photosensitive resin composition according to claim 2, characterized in that, The grade of polyether-type polyurethane acrylate is CN991.

5. The high-toughness photosensitive resin composition according to claim 1, characterized in that, The particle size of the surface-modified nano-silica is 20-50 nm.

6. The high-toughness photosensitive resin composition according to claim 5, characterized in that, The surface-modified nano-silica is nano-silica modified with a silane coupling agent.

7. A method for preparing a high-toughness photosensitive resin composition as described in any one of claims 1-6, characterized in that, include: Step 1: GOQDs Pretreatment: Add epoxy resin oligomer to the reaction vessel, heat to 60℃, add GOQDS with surface-grafted acrylate groups, perform ultrasonic dispersion, add imidazole catalyst, heat to 80-90℃, mechanically stir the reaction for 0.5-1h, monitor viscosity in real time until the viscosity increases by 20%-25%, 910cm -1 After the peak intensity of the epoxy group decreases by 20%-25%, the temperature is lowered to 40-42℃; Step 2: Maintaining a temperature of 40-42℃, add the acrylate oligomer and polyurethane acrylate sequentially. After stirring until homogeneous, add the surface-modified nano-silica and fumed silica. Perform high-speed shearing until uniformly dispersed. Then, cool to 25-30℃ and add the core-shell toughening resin and reactive diluent. Stir for 20-30 minutes to obtain a viscosity of 5000-8000 mPa. The product of s; Step 4: After adding the photoinitiator under light-protected conditions and stirring until there is no particle agglomeration, vacuum degassing is performed to obtain the photosensitive resin composition.

8. The method for preparing the high-toughness photosensitive resin composition according to claim 7, characterized in that, In step 3, if the product viscosity is greater than 8000 mPa Add 0.5-1 part of 1,6-hexanediol diacrylate and continue stirring until the viscosity of the product is 5000-8000 mPa. s.

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