SLA3D printing photosensitive resin material for industrial-grade precision casting and preparation method of SLA3D printing photosensitive resin material

Abstract

The invention discloses an industrial-grade SLA3D printing photosensitive resin material for precision casting and a preparation method of the SLA3D printing photosensitive resin material. The SLA3D printing photosensitive resin material is prepared from 50 to 70 parts of active oligomer, 15 to 25 parts of active diluent, 15 to 25 parts of high-reactivity monomer, 25 to 35 parts of photoinitiator A, 1.5 to 2.5 parts of photoinitiator B and 0.02 to 0.03 part of color paste, the ratio of the photoinitiator A to the photoinitiator B is (15-17): 1; and the tolerance of the color paste is + / -2.38%. According to the SLA3D printing photosensitive resin material, the residual ash rate can be effectively reduced by precisely regulating and controlling the components and the proportion, and the sand hole defect of a casting is greatly reduced; the linear shrinkage rate and the casting size deviation can be stabilized, and precise forming is guaranteed; the preparation process comprises the steps of yellow light feeding, vacuum stirring, 100-mesh filtering and the like, raw material prepolymerization and bubble residues can be avoided, stable material performance is ensured, and large-scale application of the SLA technology in industrial-grade precision casting is assisted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of 3D printing, and particularly relates to an SLA 3D printing photosensitive resin material for industrial precision casting and a preparation method thereof. BACKGROUND

[0002] Since the invention of stereolithography (SLA) 3D printing technology in the early 1980s, it has been widely used in the fields of industrial design and mold manufacturing by virtue of the core principle of layer-by-layer scanning and curing of photosensitive resin with ultraviolet laser. In particular, it has shown outstanding advantages in the precision casting industry. Traditional precision casting (such as sand casting and investment casting) needs complex pre-processes such as manual or mechanical manufacturing of wax molds and ceramic shells. However, relying on digital design and rapid prototyping capabilities, SLA technology can not only ensure high precision and excellent surface quality of the prototype, but also adapt to small batch production and customized manufacturing of complex parts, effectively solving the industry demand for efficient and accurate manufacturing of complex structure castings, and becoming a key technology direction to promote the innovation of precision casting process.

[0003] Although SLA technology has great potential in the field of precision casting, its application scale is still limited by the performance bottleneck of existing photosensitive resin materials. The general photosensitive resin on the market often has high residual ash rate, poor thermal stability and large linear shrinkage rate during high-temperature baking, which cannot meet the stringent requirements of size accuracy and surface quality in the casting process. For example, the existing resin is not completely decomposed under high-temperature conditions, and the residual ash rate is generally higher than 0.3%, which easily forms sand eye defects in the casting, seriously affecting the flaw detection qualification rate. At the same time, due to the superposition of polymerization shrinkage, thermal shrinkage and post-curing shrinkage during the curing process, the linear shrinkage rate exceeds 1.5%, causing the size deviation of the mold, which is difficult to meet the industry standards in the aviation industry. In addition, the existing resin also has process shortcomings in the aspects of photoinitiator ratio and colorant control. The instability of the photoinitiator system leads to uneven curing depth, affecting the interlayer bonding strength; and the lack of colorant addition precision causes the fluctuation of ultraviolet absorption rate, which further affects the stability of the critical curing energy, resulting in the decline of the surface quality of the printed part.

[0004] In summary, the development of an SLA 3D printing photosensitive resin material and its preparation method specially used for industrial precision casting has key significance for breaking through the performance bottleneck of current resin materials in high-temperature casting environment. The breakthrough in this direction is expected to significantly improve the control of residual ash and shrinkage rate, and provide a reliable forming basis for the rapid and high-precision manufacturing of complex structure castings, thereby further promoting the in-depth application and continuous development of 3D printing technology in the precision casting industry, and enabling the efficient production of high-end equipment manufacturing and complex parts. SUMMARY

[0005] In view of the problems of high residual ash rate of photosensitive resin in the prior art, causing casting sand eye, linear shrinkage >1.5% causing size out-of-tolerance, synergistic failure of photoinitiator and insufficient color paste precision, etc., the application provides a kind of SLA 3D printing photosensitive resin material for industrial precision casting and a preparation method thereof.

[0006] According to one aspect of the application, an SLA 3D printing photosensitive resin material for industrial precision casting is provided, comprising, by mass fraction, 50-70 parts of active oligomer, 15-25 parts of active diluent, 15-25 parts of high-reactivity monomer, 25-35 parts of A photoinitiator, 1.5-2.5 parts of B photoinitiator, and 0.02-0.03 parts of color paste; the ratio of A photoinitiator to B photoinitiator is 15-17:1; the tolerance of the color paste is ±2.38%.

[0007] This scheme can make the obtained material have low residual ash rate and low linear shrinkage rate while maintaining high printing precision, fully meeting the stringent requirements of industrial precision casting on model size stability and surface integrity.

[0008] Specifically, the ratio of A photoinitiator to B photoinitiator is limited to the range of 15-17:1, which can ensure the optimal balance between the rate and depth of photocuring reaction, allowing the resin to be fully cured within 10±1 seconds, while effectively inhibiting the problem of decreased interlayer peeling strength caused by improper photoinitiator ratio.

[0009] Specifically, the addition of color paste is controlled with a precision tolerance of ±2.38%, which can significantly reduce the fluctuation of ultraviolet light absorption rate and ensure the stability of critical curing energy, thereby avoiding periodic stripe defects on the surface of the printed part and improving the quality of the formed surface.

[0010] Preferably, the active oligomer includes at least one of difunctional aliphatic polyurethane acrylate, epoxy acrylate, and polyester acrylate. As the main skeletal component of the resin system, active oligomer builds the basic structure of photosensitive resin, providing flexibility, low shrinkage, and sufficient mechanical strength.

[0011] Preferably, the active diluent includes at least one of dipropylene glycol diacrylate, tripropylene glycol diacrylate, and ethoxylated trimethylolpropane triacrylate. As an active dilution component, active diluent is used to reduce the viscosity of the resin system, improve printing fluidity, and participate in photocuring cross-linking reaction.

[0012] Preferably, the high-reactivity monomer includes at least one of acryloyl morpholine, N-vinyl pyrrolidone, and isobornyl acrylate. As a curing promotion and surface optimization component, high-reactivity monomer is used to improve the photocuring rate and improve the surface flatness and curing uniformity of the printed prototype.

[0013] Preferably, the A photoinitiator includes at least one of a heat-resistant trifunctional acrylate resin, an alpha-hydroxy ketone photoinitiator, and an acyl phosphine oxide; and the B photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, and 1-hydroxycyclohexyl phenyl ketone. The A photoinitiator, as the main photoinitiator, can enhance the cross-linking density of the resin and improve the heat resistance and dimensional stability of the material; and the B photoinitiator, as a high-efficiency free radical photoinitiator, is used to cooperatively control the curing depth with the A photoinitiator.

[0014] Preferably, the color paste includes at least one of an iron red-titanium composite inorganic color paste, an iron oxide black-titanium composite color paste, and a titanium white-based color paste. The color paste can be used as an ultraviolet light absorption regulator to accurately control the penetration depth of ultraviolet light in the resin and ensure the stability of the critical curing energy (Ec) of SLA printing.

[0015] According to a second aspect of the present application, a preparation method of an industrial-grade SLA 3D printing photosensitive resin material for precision casting is provided, including the following steps:

[0016] S1. In a yellow light environment with an illumination intensity of ≤500 lux, the active oligomer, active diluent, A photoinitiator, and B photoinitiator are sequentially added to a reaction container; the ratio of the A photoinitiator to the B photoinitiator is 15-17:1;

[0017] S2. The color paste is added to the mixed system obtained in S1 to uniformly disperse the color paste in the mixed system; the tolerance of the color paste is ±2.38%;

[0018] S3. After the dispersion of the color paste is completed, the high-reactivity monomer is added, and stirring is performed under vacuum conditions. After the stirring is completed, a resin mixed solution is obtained.

[0019] S4. The resin mixed solution is filtered to obtain the industrial-grade SLA 3D printing photosensitive resin material for precision casting.

[0020] Preferably, in S3, the reaction conditions are 40℃ and -0.08MPa under vacuum stirring. In a vacuum environment (-0.08MPa), the dissolved or entrained bubbles in the mixed solution during stirring can be effectively removed. At 40℃, the viscosity of the resin system is moderately reduced, and the fluidity is enhanced, which greatly promotes the full and uniform mixing of the high-reactivity monomer with other components, ensuring the uniformity of the chemical properties of the entire resin system and the consistency of each layer of the printing.

[0021] Preferably, in the S4, the filter mesh number is 100 meshes. This mesh number can effectively trap mechanical impurities, insufficiently dispersed particles or environmental dust that may be introduced during feeding and stirring, and avoid casting sand holes.

[0022] Preferably, the prepared industrial-grade SLA 3D printing photosensitive resin material for precision casting is stored in a light-proof black glue jar and sealed with nitrogen. Light-proof storage can prevent premature curing of the resin, and nitrogen sealing can effectively isolate oxygen and block oxidation.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] (1) The industrial-grade SLA 3D printing photosensitive resin material for precision casting of the present application can control the resin residual ash rate to 0.17%-0.20%, which is much lower than the general 0.35%-0.5% of the prior art, and can greatly reduce the risk of casting sand hole defects; at the same time, the linear shrinkage rate is stable at 0.73%-0.81%, which is lower than the industry standard of 1.5%, and the casting size deviation is also within the range of ≤25μm;

[0025] (2) The industrial-grade SLA 3D printing photosensitive resin material for precision casting of the present application realizes rapid and uniform depth curing under the synergistic action of two kinds of photoinitiators, effectively avoiding the problem of decreased interlayer bonding force caused by poor synergistic action of photoinitiators; at the same time, strict tolerance control is implemented on the amount of colorant added, which significantly reduces the fluctuation of ultraviolet light absorption rate, thereby ensuring the stability of the critical curing energy, fundamentally inhibiting the appearance of periodic stripes and other defects on the surface of the printed part, and significantly improving the surface quality of the formed part;

[0026] (3) The preparation method of the industrial-grade SLA 3D printing photosensitive resin material for precision casting of the present application effectively avoids pre-polymerization through optimized feeding sequence, vacuum stirring and nitrogen sealing process steps, ensuring the uniformity and storage stability of the resin components, and the obtained material has excellent printing suitability and operation window, providing a high-reliability and repeatable 3D printing material solution for industrial-grade precision casting, and effectively promoting the technical progress of the precision casting industry. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments and, together with the description, serve to explain the principles of the present application. Other embodiments and many of the intended advantages of the present application will be readily appreciated as the same becomes better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale. Like reference numerals designate corresponding similar parts throughout the various views.

[0028] Figure 1A flow chart of a preparation method of an SLA 3D printing photosensitive resin material for industrial precision casting according to an embodiment of the present application is shown.

[0029] Figures 2a-2c A physical map of the SLA 3D printing photosensitive resin material prepared in different color paste amounts is shown. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for ease of description.

[0031] The embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0032] Figure 1 A flow chart of a preparation method of an SLA 3D printing photosensitive resin material for industrial precision casting is shown, referring to Figure 1 , the specific preparation method is as follows:

[0033] S1, in a yellow light environment with an illumination intensity not exceeding 500 lux, sequentially add the pre-weighed active oligomer, active diluent, A photoinitiator and B photoinitiator into a clean reaction container; the ratio of A photoinitiator to B photoinitiator is in the range of 15-17:1. Continuous slow stirring is required during the addition process to ensure that the components are initially mixed uniformly and to avoid local high concentration leading to pre-polymerization. After completing the initial mixing, it is necessary to stand still to make the bubbles float up.

[0034] S2, slowly inject the color paste into the mixed system after S1 standing, continuously stir at a speed of 800 rpm during the injection process, the dispersion time is 20 min, and the color uniformity of the mixed system is observed in real time during the dispersion process to ensure that the color paste forms a stable dispersion in the resin matrix. The color paste addition amount is controlled within ±2.38% of the theoretical value.

[0035] S3, after the color paste dispersion verification is qualified, add high reactivity monomers for stirring, the stirring needs to be carried out in a vacuum environment, the vacuum degree is maintained at-0.08 MPa, and the stirring temperature is controlled at 40°C, which not only ensures the fluidity of the resin system, but also avoids overheating to cause the photoinitiator to decompose in advance. The whole stirring process lasts for 1 h.

[0036] S4, filter the resin mixed liquid prepared in S3 through a 100 mesh stainless steel filter screen, and install the filter screen in a closed filtration system to prevent oxygen contact. The filtered resin is immediately transferred into a pre-nitrogen-filled light-proof black glue tank for sealed storage.

[0037] Specifically, the active oligomer includes at least one of difunctional aliphatic polyurethane acrylate, epoxy acrylate and polyester acrylate.

[0038] Specifically, the active diluent includes at least one of dipropylene glycol diacrylate, tripropylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate.

[0039] Specifically, the high-reactivity monomer includes at least one of acryloyl morpholine, N-vinyl pyrrolidone and isobornyl acrylate.

[0040] Specifically, the A photoinitiator includes at least one of heat-resistant trifunctional acrylate resin, alpha-hydroxy ketone photoinitiator and acyl phosphine oxide; the B photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide and 1-hydroxycyclohexyl phenyl ketone.

[0041] Specifically, the color paste includes at least one of iron red-titanium-based composite inorganic color paste, iron oxide black-titanium-based composite color paste and titanium white-based color paste.

[0042] Embodiment one

[0043] An industrial-grade SLA 3D printing photosensitive resin material for precision casting, by mass fraction, includes difunctional aliphatic polyurethane acrylate 50 parts, dipropylene glycol diacrylate 25 parts, acryloyl morpholine 25 parts, heat-resistant trifunctional acrylate resin 35 parts, 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide 2.19 parts and iron red-titanium-based composite inorganic color paste (Fe2O3 / TiO4) 0.021 parts; the ratio of heat-resistant trifunctional acrylate resin to 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 16:1. The preparation method is as follows:

[0044] S101, in a yellow light environment with an illumination intensity not exceeding 500 lux, sequentially add 50 parts of difunctional aliphatic polyurethane acrylate, 25 parts of dipropylene glycol diacrylate, 35 parts of heat-resistant trifunctional acrylate resin and 2.19 parts of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide into a clean reaction container. Slowly stir during the addition process, and after the initial mixing is completed, let the bubbles float up.

[0045] S102, slowly inject 0.021 parts of iron red-titanium-based composite inorganic color paste into the mixed system after S101 is placed, continuously stir at a speed of 800 rpm during the injection process, and the dispersion time is 20 min.

[0046] S103, after the color paste dispersion verification is qualified, 25 parts of acryloyl morpholine is added for stirring, the stirring needs to be carried out in a vacuum environment, the vacuum degree is maintained at-0.08 MPa, and the stirring temperature is controlled at 40 DEG C.

[0047] S104, the resin mixed solution prepared in S103 is filtered through a 100 mesh stainless steel filter screen, and the filtered resin is immediately transferred into a pre-charged nitrogen light-proof black glue tank for sealing and preservation.

[0048] Example two

[0049] An industrial-grade SLA 3D printing photosensitive resin material for precision casting, by mass fraction, includes 60 parts of difunctional aliphatic polyurethane acrylate, 20 parts of dipropylene glycol diacrylate, 20 parts of acryloyl morpholine, 30 parts of heat-resistant trifunctional acrylate resin, 1.88 parts of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide and 0.021 parts of iron red-titanium composite inorganic color paste (Fe2O3 / TiO4); the ratio of heat-resistant trifunctional acrylate resin to 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 16:1. The preparation method is as follows:

[0050] S201, in a yellow light environment with an illumination intensity of not more than 500 lux, 60 parts of difunctional aliphatic polyurethane acrylate, 20 parts of dipropylene glycol diacrylate, 30 parts of heat-resistant trifunctional acrylate resin and 1.88 parts of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide are sequentially added into a clean reaction container. Slow stirring is continuously carried out during the adding process, and after the initial mixing is completed, the gas bubbles are allowed to float up.

[0051] S202, 0.021 parts of iron red-titanium composite inorganic color paste is slowly injected into the mixed system after S201 is placed, and stirring is continuously carried out at a speed of 800 rpm during the injection process, and the dispersion time is 20 min.

[0052] S203, after the color paste dispersion verification is qualified, 20 parts of acryloyl morpholine is added for stirring, the stirring needs to be carried out in a vacuum environment, the vacuum degree is maintained at-0.08 MPa, and the stirring temperature is controlled at 40 DEG C.

[0053] S204, the resin mixed solution prepared in S203 is filtered through a 100 mesh stainless steel filter screen, and the filtered resin is immediately transferred into a pre-charged nitrogen light-proof black glue tank for sealing and preservation.

[0054] Example three

[0055] An industrial-grade SLA 3D printing photosensitive resin material for precision casting, comprising, by mass fraction, 70 parts of difunctional aliphatic polyurethane acrylate, 15 parts of dipropylene glycol diacrylate, 15 parts of acryloyl morpholine, 25 parts of heat-resistant trifunctional acrylate resin, 1.56 parts of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, and 0.021 parts of iron red-titanium composite inorganic color paste (Fe2O3 / TiO4); the ratio of heat-resistant trifunctional acrylate resin to 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 16:1. The preparation method is as follows:

[0056] S301, in a yellow light environment with an illumination intensity not exceeding 500 lux, 70 parts of difunctional aliphatic polyurethane acrylate, 15 parts of dipropylene glycol diacrylate, 25 parts of heat-resistant trifunctional acrylate resin, and 1.56 parts of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide are sequentially added into a clean reaction container. Slow stirring is continuously performed during the addition process, and after the preliminary mixing is completed, standing is performed to make the gas bubbles float up.

[0057] S302, 0.021 parts of iron red-titanium composite inorganic color paste are slowly injected into the mixed system after standing in S301, and stirring is continuously performed at a speed of 800 rpm during the injection process, and the dispersion time is 20 min.

[0058] S303, after the color paste dispersion verification is qualified, 15 parts of acryloyl morpholine is added for stirring, and the stirring needs to be performed in a vacuum environment, the vacuum degree is maintained at-0.08 MPa, and the stirring temperature is controlled at 40°C.

[0059] S304, the resin mixed solution prepared in S303 is filtered through a 100-mesh stainless steel filter screen, and the filtered resin is immediately transferred into a pre-charged nitrogen light-proof black glue tank for sealed storage.

[0060] Example Four

[0061] An industrial-grade SLA 3D printing photosensitive resin material for precision casting, which is different from example two in that the heat-resistant trifunctional acrylate resin is 30 parts, the 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 2.0 parts, and the ratio of the two is 15:1. The preparation method is consistent with example two.

[0062] Example Five

[0063] An industrial-grade SLA 3D printing photosensitive resin material for precision casting, which is different from example two in that the heat-resistant trifunctional acrylate resin is 30 parts, the 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 1.76 parts, and the ratio of the two is 17:1. The preparation method is consistent with example two.

[0064] Comparative Example One

[0065] An SLA 3D printing photosensitive resin material, comprising 60wt% of epoxy acrylate (active oligomer), 30wt% of tripropylene glycol diacrylate (active diluent), 2.5wt% of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide (photoinitiator), 5wt% of polypropylene glycol with a molecular weight of 400 (inert additive), and 2.5wt% of modified polydimethylsiloxane (leveling agent).

[0066] Comparative Example Two

[0067] An SLA 3D printing photosensitive resin material, comprising, by mass fraction, 60 parts of difunctional aliphatic polyurethane acrylate, 20 parts of dipropylene glycol diacrylate, 20 parts of acryloyl morpholine, 30 parts of heat-resistant trifunctional acrylate resin, 2.14 parts of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, and 0.021 parts of iron red-titanium-based composite inorganic color paste; the ratio of heat-resistant trifunctional acrylate resin to 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 14:1. The preparation method is the same as that of Example Two.

[0068] Comparative Example Three

[0069] An SLA 3D printing photosensitive resin material, comprising, by mass fraction, 60 parts of difunctional aliphatic polyurethane acrylate, 20 parts of dipropylene glycol diacrylate, 20 parts of acryloyl morpholine, 30 parts of heat-resistant trifunctional acrylate resin, 1.5 parts of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, and 0.021 parts of iron red-titanium-based composite inorganic color paste; the ratio of heat-resistant trifunctional acrylate resin to 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 20:1. The preparation method is the same as that of Example Two.

[0070] Comparative Example Four

[0071] An SLA 3D printing photosensitive resin material, which is different from Example Two in that the iron red-titanium-based composite inorganic color paste is 0.01 part.

[0072] Comparative Example Five

[0073] An SLA 3D printing photosensitive resin material, which is different from Example Two in that the iron red-titanium-based composite inorganic color paste is 0.06 part.

[0074] The performance index test results of the SLA 3D printing photosensitive resin materials prepared in each example and Comparative Example One are shown in Table 1.

[0075] Table 1

[0076]

[0077] The results show that the residual ash rates of Examples 1-3 were controlled at 0.19%, 0.17%, and 0.20%, respectively, which are far lower than the 0.42% of Comparative Example 1. This indicates that optimizing the resin composition and ratio can effectively reduce the risk of sand hole defects in castings. The linear shrinkage rate was stable within the range of 0.73%-0.81%, significantly better than the 1.58% of the Comparative Example, ensuring the dimensional accuracy of the castings. The dimensional deviation of the casting in Example 2 was 22 μm, while that in Comparative Example 1 reached 53 μm, further verifying the accuracy of dimensional control of the material in this application. In addition, the X-ray flaw detection pass rate of Example 2 reached 99.5%, and the surface roughness Ra was as low as 3.8, both of which were better than the 90.8% and 8.2 of Comparative Example 1, indicating that the material has a significant improvement in internal quality and surface forming effect.

[0078] Furthermore, the key indicators of Comparative Example 1, such as residual ash rate and linear shrinkage rate, were significantly worse than those of the Example. The pass rate of X-ray flaw detection was only 90.8%, and the surface roughness Ra was as high as 8.2. This indicates that the traditional formula has obvious limitations in precision casting applications.

[0079] Table 2 shows the performance test results of SLA 3D printing photosensitive resin materials prepared with different photoinitiator ratios (Examples 2, 4, 5, and Comparative Examples 2-3).

[0080] Table 2

[0081]

[0082] As shown in Table 2, the ratio of photoinitiator has a significant impact on the material properties.

[0083] When the ratio of heat-resistant trifunctional acrylate resin to 2,4,6-trimethylbenzoyl-diphenylphosphine oxide was 16:1 (Example 2), the curing depth fluctuation was only ±5 μm, the interlayer peel strength reached 12.5 MPa, and the material achieved optimal applicability within 10 ± 1 s of complete curing, indicating the best material performance. In Comparative Example 2, when the ratio was changed to 14:1, the curing depth fluctuation increased to ±18 μm, and the interlayer peel strength decreased to 8.2 MPa, exhibiting uneven curing and easy delamination. In Comparative Example 3, when the ratio was adjusted to 20:1, the curing depth fluctuation was ±12 μm, and the interlayer peel strength was 9.1 MPa, indicating insufficient curing and weakened strength. This shows that the photoinitiator ratio is a key factor in controlling the uniformity of resin curing depth; improper ratios can lead to weakened interlayer bonding, resulting in dimensional expansion and internal defects. Example 2, by strictly maintaining a 16:1 ratio, achieved synergistic optimization of shrinkage rate, dimensional accuracy, and surface quality, verifying the performance improvement effect of the dual photoinitiator synergistic system on precision casting materials.

[0084] Figures 2a-2cThe images show physical images of the SLA 3D printing photosensitive resin materials prepared in Example 2, Comparative Example 4, and Comparative Example 5, respectively. As can be seen from the images, the SLA 3D printing photosensitive resin liquid prepared in Example 2 (… Figure 2a The pigment exhibits a uniform, delicate dark red color with rich hue, even light transmission, and no visible impurities or layering. At this concentration, the pigment can precisely and stably control the penetration of ultraviolet light, ensuring a high degree of consistency in the critical curing energy. This results in a stripe-free, high-precision printing surface (surface roughness Ra = 3.8) and an extremely low residual ash rate (0.17%), perfectly meeting the stringent requirements of industrial-grade precision casting for model quality.

[0085] The SLA 3D printing photosensitive resin liquid prepared in Comparative Example 4 ( Figure 2b The color is noticeably lighter and yellowish. This is because the content of the pigment paste, acting as a UV light absorption regulator, is insufficient, failing to effectively and stably control the penetration depth of UV light in the resin. This causes fluctuations in the critical curing energy (Ec) during printing, resulting in uneven curing depth. Specifically, this manifests on the printed parts as obvious periodic laser scanning stripes on the surface. Furthermore, due to localized over-curing, the residual ash rate increases to 0.35% during subsequent firing, severely impacting the internal quality of the casting.

[0086] In addition, the SLA 3D printing photosensitive resin liquid prepared in Comparative Example 5 ( Figure 2c The color is too dark, appearing as an almost opaque dark brownish-red. This is because excessive pigment absorbs too much ultraviolet light, severely hindering light penetration and resulting in insufficient depth of the photocuring reaction. This leads to incomplete curing of the bottom layer or thick-walled areas of the printed part, a significant decrease in interlayer adhesion (interlayer peel strength drops to 8.8 MPa), and a tendency to deform or crack during demolding and post-curing. Simultaneously, excessive inorganic pigment also contributes to high-temperature residual ash, increasing its residual ash rate to 0.38%.

[0087] This indicates that the amount of pigment is not necessarily better the more or the less, but rather there is a precise optimal window (0.02-0.03 parts). The amount of pigment used in the industrial-grade precision casting SLA 3D printing photosensitive resin material of this application ensures that the resin material has stable and reliable curing performance during the SLA printing process, which plays an important role in achieving the technical effects of low residual ash, low shrinkage, and high-precision casting.

[0088] In summary, the industrial-grade precision casting SLA 3D printing photosensitive resin material proposed in this application, through the combined innovation of "aliphatic oligomers replacing benzene ring components," "synergistic effect of A / B photoinitiators," and "highly reactive monomers optimizing curing performance," not only solves the core pain points of existing technologies, such as residual ash causing casting pinholes and uncontrolled shrinkage leading to dimensional deviations, but also avoids the risks of raw material prepolymerization and uneven component dispersion through the process design of "yellow light environment feeding + 40℃ / -0.08MPa vacuum stirring + 100-mesh filtration," ensuring consistent performance during mass production.

[0089] The specific embodiments of this application have been described above, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0090] In the description of this application, it should be understood that the terms "upper," "lower," "inner," "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and for simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The simple fact that certain measures are recited in mutually different dependent claims does not indicate that combinations of these measures cannot be used for improvement. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. An SLA 3D printing photosensitive resin material for industrial precision casting, characterized in that, According to mass parts, including 50-70 parts of active oligomer, 15-25 parts of active diluent, 15-25 parts of high reactivity monomer, 25-35 parts of A photoinitiator, 1.5-2.3 parts of B photoinitiator and 0.02-0.03 parts of color paste; the ratio of the A photoinitiator and the B photoinitiator is 15-17:1; the tolerance of the color paste is ±2.38%.

2. The SLA 3D printing photosensitive resin material for industrial grade precision casting according to claim 1, characterized in that, The active oligomer includes at least one of difunctional aliphatic polyurethane acrylate, epoxy acrylate and polyester acrylate. 3.The SLA 3D printing photosensitive resin material for industrial-grade precision casting according to claim 1, characterized in that, The active diluent includes at least one of dipropylene glycol diacrylate, tripropylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate. 4.The SLA 3D printing photosensitive resin material for industrial-grade precision casting of claim 1, characterized in that, The high reactivity monomer includes at least one of acryloyl morpholine, N-vinyl pyrrolidone and isobornyl acrylate. 5.The SLA 3D printing photosensitive resin material for industrial-grade precision casting of claim 1, characterized in that, The A photoinitiator includes at least one of heat-resistant trifunctional acrylate resin, alpha-hydroxy ketone photoinitiator and acyl phosphine oxide; the B photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide and 1-hydroxycyclohexyl phenyl ketone. 6.The SLA 3D printing photosensitive resin material for industrial-grade precision casting of claim 1, characterized in that, The color paste includes at least one of iron red-titanium composite inorganic color paste, iron oxide black-titanium composite color paste and titanium white-based color paste.

7. A method for preparing an industrial grade precision casting SLA 3D printing photosensitive resin material according to any one of claims 1-6, characterized in that, Including the following steps: S1, under the yellow light environment with light intensity ≤500 lux, the active oligomer, the active diluent, the A photoinitiator and the B photoinitiator are sequentially added to the reaction container; the ratio of the A photoinitiator and the B photoinitiator is 15-17:1; S2, the color paste is added to the mixed system obtained in S1, so that the color paste is uniformly dispersed in the mixed system; the tolerance of the color paste is ±2.38%; S3, after the dispersion of the color paste is completed, the high reactivity monomer is added, and stirring is carried out under vacuum condition, and the resin mixed solution is obtained after the stirring is completed; S4, the resin mixed solution is filtered, and an industrial-grade SLA 3D printing photosensitive resin material for precision casting is obtained.

8. The method for preparing SLA 3D printing photosensitive resin material for industrial-grade precision casting according to claim 7, characterized in that, In S3, the reaction condition is vacuum stirring at 40°C and -0.08MPa.

9. The method for preparing the SLA 3D printing photosensitive resin material for industrial-grade precision casting according to claim 7, characterized in that, In S4, the filtering mesh size is 100 meshes.

10. The method for preparing the SLA 3D printing photosensitive resin material for industrial-grade precision casting according to claim 7, characterized in that, The prepared industrial-grade SLA 3D printing photosensitive resin material for precision casting is stored in a light-proof black glue tank and sealed by nitrogen.

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