Aluminum alloy 3D printing photosensitive resin mold and investment casting coating and its preparation method

Abstract

The present application provides a photosensitive resin mold for investment casting of 3D printing of aluminum alloy. By weight, it includes 7-10 parts of active magnesium oxide, 16-20 parts of silica sol, the solid content of the silica sol is 20%-32%, 12-18 parts of bentonite, 2-6 parts of cellulose, and 16-30 parts of epoxy resin. The present application also provides a preparation method of the coating. The coating provided by the present application is beneficial to improving the fire resistance, crack resistance and adhesion.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and particularly to a photosensitive resin mold for 3D printing of aluminum alloy and a method for preparing a investment casting coating. Background Art

[0002] Investment casting is an advanced near-net-shape forming process that can produce precision and complex castings of various alloys. The castings are close to the final shape and size of the parts and can be used directly without machining or with minimal machining. The investment casting method usually uses a fusible material to make a model, and then a refractory coating is applied to the surface of the model. After the coating hardens, dries, and cures, the model is heated to melt out the mold material to form a hollow shell. The hollow shell is sintered at high temperature and then poured with molten metal to cast metal castings.

[0003] With the development of 3D printing technology, photosensitive resin can be used as a model material. Due to the molecular characteristics of the photosensitive resin, the adhesion of the existing refractory coatings does not meet the usage requirements. In addition, the existing refractory materials crack after high-temperature sintering, thus affecting the forming quality of the castings. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide an investment casting coating for 3D printing of aluminum alloy photosensitive resin mold, which is beneficial to improving fire resistance, crack resistance, and adhesion.

[0005] The present application also provides a method for preparing the coating.

[0006] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0007] An investment casting coating for 3D printing of aluminum alloy photosensitive resin mold, by weight, comprises 7-10 parts of active magnesium oxide, 16-20 parts of silica sol, the solid content of the silica sol is 20%-32%, 12-18 parts of bentonite, 2-6 parts of cellulose, and 16-30 parts of epoxy resin.

[0008] In some possible embodiments, by weight, the silicon dioxide in the silica sol: the active magnesium oxide: the bentonite is 1:1.2-1.5:2.5-2.6.

[0009] In some possible embodiments, by weight, the epoxy resin: the cellulose is 3-7:1.

[0010] In some possible embodiments, the amount of the silica sol is 17-18 parts.

[0011] In some possible embodiments, the amount of the bentonite is 12-16 parts.

[0012] In some possible embodiments, the amount of the epoxy resin is 18 - 25 parts by weight.

[0013] In some possible embodiments, the epoxy resin is selected from one of glycidyl ether epoxy resins, glycidyl ester epoxy resins or glycidyl amine epoxy resins.

[0014] In some possible embodiments, by weight, the coating further comprises 1 - 2 parts of an additive, and the additive includes an antifoaming agent.

[0015] The present application also provides a method for preparing a coating for investment casting of an aluminum alloy 3D printing photosensitive resin mold, the preparation method uses the components of the coating as described above, and the preparation method includes the following steps:

[0016] Mix the reactive magnesium oxide into the silica sol according to a set ratio to obtain a first mixture;

[0017] Mix the bentonite and cellulose into the epoxy resin according to a set ratio to obtain a second mixture;

[0018] Mix the first mixture into the second mixture to obtain the coating.

[0019] In some possible embodiments, the mixing temperature for obtaining the first mixture is 20 - 40°C, the mixing speed is 1500 - 2000 rpm, the mixing temperature for obtaining the second mixture is 20 - 40°C, the mixing speed is 1000 - 3000 rpm, and the mixing temperature for obtaining the coating is 20 - 40°C, the mixing speed is 2000 - 3000 rpm.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] In the present application, the fire resistance of the coating is improved through the synergistic effect of reactive magnesium oxide, silica sol and bentonite. In addition, the cellulose disperses the silica in the reactive magnesium oxide, bentonite and silica sol into the epoxy resin system through polar groups such as hydroxyl groups, thereby further improving the fire resistance of the coating. In addition, the dispersion of the above-mentioned refractory particles synergistically with cellulose and epoxy resin is also beneficial to improving the crack resistance and adhesion of the coating, so that the coating of the present application can be used for the coating of investment casting of aluminum alloy 3D printing photosensitive resin mold.

[0022] The present invention will be further described in detail below in conjunction with specific embodiments. Specific Embodiments

[0023] Next, in combination with the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0025] Some embodiments of the present invention will be described in detail below. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0026] An embodiment of the present application provides a photosensitive resin mold for 3D printing of aluminum alloy and an investment casting coating. By weight, it includes 7-10 parts of active magnesium oxide, 16-20 parts of silica sol, the solid content of the silica sol is 20%-32%, 12-18 parts of bentonite, 2-6 parts of cellulose, and 16-30 parts of epoxy resin.

[0027] In some embodiments, by weight, the silicon dioxide in the silica sol: the active magnesium oxide: the bentonite is 1:1.2-1.5:2.5-2.6. The selection of this ratio is beneficial to regulating the stacking distribution density between the refractory additives, thereby facilitating further improving the synergistic effect between the refractory additives, and thus facilitating further improving the refractoriness.

[0028] In some embodiments, by weight, the epoxy resin: the cellulose is 3-7:1. The selection of this ratio is beneficial to further improving the crack resistance and adhesion of the coating, and at the same time, in coordination with the ratio selection of the refractory additives, it is beneficial to further improve the refractoriness of the coating.

[0029] In some embodiments, the amount of the silica sol is 17-18 parts.

[0030] In some embodiments, the amount of the bentonite is 12-16 parts.

[0031] In some embodiments, the amount of the epoxy resin is 18-25 parts.

[0032] The further limitation of the above amounts is beneficial in adjusting the viscosity of the coating system for easy construction on the one hand, and also beneficial in adjusting the dispersibility of the refractory additives to facilitate further improving the refractoriness on the other hand.

[0033] In some embodiments, the epoxy resin is selected from one of glycidyl ether epoxy resins, glycidyl ester epoxy resins, or glycidyl amine epoxy resins. Due to the introduction of polar groups, the specific types of the above epoxy resins are beneficial to enhancing the adhesion of the epoxy resin and also to assisting the dispersion of fillers in the epoxy resin, such as cellulose, bentonite, silica, and reactive magnesium oxide, thereby facilitating the further improvement of the fire resistance and crack resistance of the coating.

[0034] In other embodiments, the epoxy resin can be one of alicyclic epoxy resins or linear aliphatic epoxy resins.

[0035] In some embodiments, by weight, the coating further includes 1 - 2 parts of an auxiliary agent, and the auxiliary agent includes an antifoaming agent to eliminate the bubbles in the coating. Exemplarily, the antifoaming agent can include a waterborne epoxy resin antifoaming agent.

[0036] In the present application, the fire resistance of the coating is improved through the synergistic effect of reactive magnesium oxide, silica sol, and bentonite. Additionally, cellulose, through polar groups such as hydroxyl groups, assists in dispersing silica in reactive magnesium oxide, bentonite, and silica sol into the epoxy resin system, thereby further improving the fire resistance of the coating. Moreover, the dispersion of the above fire-resistant particles, in conjunction with cellulose and epoxy resin, is also beneficial to improving the crack resistance and adhesion of the coating, enabling the coating of the present application to be applied to the coating for investment casting of photosensitive resin molds in 3D printing of aluminum alloys.

[0037] Another embodiment of the present application further provides a preparation method for a coating for investment casting of photosensitive resin molds in 3D printing of aluminum alloys. The preparation method uses the components of the coating in any of the above embodiments. Therefore, the proportion selection and specific type selection of each component will not be elaborated herein. The preparation method includes the following steps:

[0038] Mix reactive magnesium oxide into silica sol according to a set ratio to obtain a first mixture.

[0039] In some embodiments, the mixing temperature for obtaining the first mixture is 20 - 40°C, and the mixing speed is 1500 - 2000 revolutions per minute. Exemplarily, the mixing speed can be 1500 revolutions per minute, 1600 revolutions per minute, 1700 revolutions per minute, 1800 revolutions per minute, 1900 revolutions per minute, or 2000 revolutions per minute, as well as the ranges between the above values. Exemplarily, the mixing temperature can be 20°C, 25°C, 30°C, 35°C, or 40°C, as well as the ranges between the above values. The selection of the above speed and temperature is to ensure the mixing and dispersion of reactive magnesium oxide.

[0040] Mix bentonite and cellulose into the epoxy resin according to a set ratio to obtain a second mixture.

[0041] In some embodiments, the mixing temperature for obtaining the second mixture is 20 - 40°C, and the mixing speed is 1000 - 3000 revolutions per minute. Exemplarily, the mixing speed can be 1000 revolutions per minute, 1500 revolutions per minute, 1700 revolutions per minute, 1800 revolutions per minute, 1900 revolutions per minute, 2000 revolutions per minute, 2500 revolutions per minute, or 3000 revolutions per minute, as well as the ranges between the above values. Exemplarily, the mixing temperature can be 20°C, 25°C, 30°C, 35°C, or 40°C, as well as the ranges between the above values. The selection of the above speeds and temperatures is to ensure the mixing and dispersion of bentonite and cellulose.

[0042] Mix the first mixture into the second mixture to obtain a coating.

[0043] In some embodiments, the mixing temperature for obtaining the coating is 20 - 40°C, and the mixing speed is 2000 - 3000 revolutions per minute. Exemplarily, the mixing speed can be 2000 revolutions per minute, 2100 revolutions per minute, 2200 revolutions per minute, 2300 revolutions per minute, 2400 revolutions per minute, 2500 revolutions per minute, 2600 revolutions per minute, 2700 revolutions per minute, 2800 revolutions per minute, 2900 revolutions per minute, or 3000 revolutions per minute, as well as the ranges between the above values. Exemplarily, the mixing temperature can be 20°C, 25°C, 30°C, 35°C, or 40°C, as well as the ranges between the above values. The selection of the above speeds and temperatures is to ensure the mixing and dispersion of refractory fillers. The mixing speed can fluctuate within a certain range according to the stirring condition.

[0044] A high-speed shearing machine can be used to mix the above materials. In specific use, the mixed coating can be loaded into a coating spray gun, shaken evenly, and then sprayed on a 3D printing photosensitive resin model.

[0045] Specifically:

[0046] Example 1:

[0047] A photosensitive resin mold for investment casting coating for 3D printing of aluminum alloy, by weight, includes 7 parts of active magnesium oxide (Zehui magnesium-based, ZH-M600), 20 parts of silica sol (Huierte R & D Company, HS-830A), the solid content of the silica sol is 30% (average value), 12 parts of bentonite (sodium-based bentonite, Dongguan Ruiheng Mineral Products Co., Ltd.), 4 parts of cellulose (sigma-AIdrich, S6790), 16 parts of epoxy resin and 1 part of defoaming agent (aqueous epoxy resin defoaming agent, Guangzhou Yang's Chemical Technology Co., Ltd., YS-T118). The silica in the silica sol: the active magnesium oxide: the bentonite is 1:1.16:2. The average particle size of the active magnesium oxide is 1 µm, and the average particle size of the bentonite is 5 µm. The epoxy resin: the cellulose is 4:1. The epoxy resin is a glycidyl ether type epoxy resin, specifically tetraphenylethane tetraglycidyl ether epoxy resin (Wengjiang reagent - PA40079).

[0048] The specific preparation method is as follows:

[0049] Mix the active magnesium oxide into the silica sol according to the set ratio to obtain the first mixture. The mixing temperature for obtaining the first mixture is 30 °C, and the mixing speed is 1800 - 2000 rpm.

[0050] Mix the bentonite and cellulose into the epoxy resin according to the set ratio to obtain the second mixture. The mixing temperature for obtaining the second mixture is 30 °C, and the mixing speed is 2400 - 2500 rpm;

[0051] Mix the first mixture into the second mixture to obtain the coating. The mixing temperature for obtaining the coating is 30 °C, and the mixing speed is 2900 - 3000 rpm.

[0052] Example 2:

[0053] The difference from Example 1 is that, by weight, the coating includes 10 parts of active magnesium oxide, 16 parts of silica sol, 18 parts of bentonite, 2 parts of cellulose, 30 parts of epoxy resin and 1 part of defoaming agent. The silica in the silica sol: the active magnesium oxide: the bentonite is 1:2.1:3.8. The epoxy resin: the cellulose is 15:1. The epoxy resin is a glycidyl ester type epoxy resin (4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester epoxy resin, TDE-85, Guangzhou Xian'an Chemical Co., Ltd.).

[0054] The specific preparation method is as follows:

[0055] Mix the reactive magnesium oxide into the silica sol in a set ratio to obtain a first mixture. The mixing temperature for obtaining the first mixture is 25 °C, and the mixing speed is 1900 - 2000 rpm.

[0056] Mix bentonite and cellulose into the epoxy resin in a set ratio to obtain a second mixture. The mixing temperature for obtaining the second mixture is 25 °C, and the mixing speed is 2900 - 3000 rpm;

[0057] Mix the first mixture into the second mixture to obtain a coating. The mixing temperature for obtaining the coating is 25 °C, and the mixing speed is 2900 - 3000 rpm.

[0058] Example 3:

[0059] The difference from Example 1 is that, by weight, the coating includes 9 parts of reactive magnesium oxide, 19 parts of silica sol, 17 parts of bentonite, 5 parts of cellulose, 26 parts of epoxy resin, and 2 parts of defoamer. The silica in the silica sol: the reactive magnesium oxide: the bentonite is 1:1.58:2.98. The epoxy resin: the cellulose is 5.2:1. The epoxy resin is a glycidylamine epoxy resin (4,4-diaminodiphenylmethane tetraglycidylamine epoxy resin, Huineng - AG80).

[0060] The specific preparation method is as follows:

[0061] Mix the reactive magnesium oxide into the silica sol in a set ratio to obtain a first mixture. The mixing temperature for obtaining the first mixture is 40 °C, and the mixing speed is 1500 - 1600 rpm.

[0062] Mix bentonite and cellulose into the epoxy resin in a set ratio to obtain a second mixture. The mixing temperature for obtaining the second mixture is 40 °C, and the mixing speed is 1000 - 1200 rpm;

[0063] Mix the first mixture into the second mixture to obtain a coating. The mixing temperature for obtaining the coating is 40 °C, and the mixing speed is 2100 - 2200 rpm.

[0064] Example 4:

[0065] The difference from Example 1 is that the weight fraction of the silica sol is 17 parts, the weight fraction of the reactive magnesium oxide is 7.65 parts, the weight fraction of the bentonite is 12.75 parts, and the silica in the silica sol: the reactive magnesium oxide: the bentonite is 1:1.5:2.5.

[0066] Example 5:

[0067] Differing from Example 1, the weight fraction of the active magnesium oxide is 7.2 parts, the weight fraction of the bentonite is 15.6 parts, and the silicon dioxide in the silica sol: the active magnesium oxide: the bentonite is 1:1.2:2.6.

[0068] Example 6:

[0069] Differing from Example 1, the weight fraction of the silica sol is 18 parts, the weight fraction of the active magnesium oxide is 7.56 parts, the weight fraction of the bentonite is 13.5 parts, and the silicon dioxide in the silica sol: the active magnesium oxide: the bentonite is 1:1.4:2.5.

[0070] Example 7:

[0071] Differing from Example 6, the weight fraction of the cellulose is 4.2 parts, the weight fraction of the epoxy resin is 29.7 parts, and the epoxy resin: the cellulose is 7:1.

[0072] Example 8:

[0073] Differing from Example 6, the weight fraction of the cellulose is 6 parts, the weight fraction of the epoxy resin is 18 parts, and the epoxy resin: the cellulose is 3:1

[0074] Example 9:

[0075] Differing from Example 6, the weight fraction of the cellulose is 5 parts, the weight fraction of the epoxy resin is 25 parts, and the epoxy resin: the cellulose is 5:1.

[0076] Comparative Example 1:

[0077] Differing from Example 1, the coating lacks active magnesium oxide. During preparation, the silica sol is mixed into the premixed bentonite, cellulose, and epoxy resin. The mixing conditions are the same as those in the second and third steps of Example 1.

[0078] Comparative Example 2:

[0079] Differing from Example 1, the coating lacks bentonite. During preparation, only the cellulose is mixed into the epoxy resin, and other conditions or steps remain unchanged.

[0080] Comparative Example 3:

[0081] Differing from Example 1, the coating lacks silica sol. During preparation, the active magnesium oxide is mixed into the premixed bentonite, cellulose, and epoxy resin. The mixing conditions are the same as those in the second and third steps of Example 1.

[0082] Comparative Example 4:

[0083] It is different from Example 1 in that the coating lacks cellulose. During preparation, in the second step, bentonite is mixed into the epoxy resin, and other operation steps and conditions remain unchanged.

[0084] The performance of the coating in this application is tested through the following standards.

[0085] 1. Fire resistance: Test the fire resistance limit of the coating. Test according to the national standard GB / T 9978 to measure the highest temperature that the coating can withstand.

[0086] 2. Crack resistance: Coat the coating on a photosensitive resin plate and cure it to prepare a specimen. Place the specimen in a high-temperature tensile testing machine for tensile testing to measure the elongation at break. The test temperature is 750 °C.

[0087] 3. Adhesion: Test by the pull-off method. Specifically, apply the test sample with a uniform thickness on a flat plate with a consistent surface structure (the material of the flat plate is photosensitive resin). After waiting for the coating system to dry or cure, place it in a high-temperature furnace and bake it at 750 °C for 30 min (the pouring temperature of aluminum alloys). Take out the baked coating sample and let it cool naturally at room temperature. Use an adhesive to directly bond the test column to the surface of the coating. After the adhesive cures, place the bonded test combination on a suitable tensile testing machine. The bonded test combination undergoes a controlled tensile test to measure the tensile force required to break the adhesion between the coating and the substrate, and use the tensile force to represent the adhesion strength.

[0088] During the above tests, the dry film thickness of the coating can be controlled at 1 mm.

[0089] The test results of the above examples and comparative examples of this application are shown in the following table.

[0090]

[0091] From the test results of the above examples and comparative examples, it can be seen that active magnesium oxide, silica sol, and bentonite play a synergistic role with the assistance of cellulose, which is beneficial to improving the fire resistance, crack resistance, and adhesion of the coating. Comparing Examples 1 to 3 with Examples 4 to 9, it can be seen that restricting the proportion of specific components is beneficial to further improving the fire resistance, crack resistance, and adhesion of the coating.

[0092] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

Claims

1. A 3D printing photosensitive resin mold investment casting coating for aluminum alloy, characterized in that: By weight, it comprises 7-10 parts of active magnesium oxide, 16-20 parts of silica sol, wherein the solid content of the silica sol is 20%-32%, 12-18 parts of bentonite, 2-6 parts of cellulose and 16-30 parts of epoxy resin.

2. The coating according to claim 1, characterized in that By weight, the ratio of silicon dioxide in the silica sol: the active magnesium oxide: the bentonite is 1:1.2-1.5:2.5-2.

6.

3. The coating according to claim 2, characterized in that By weight, the epoxy resin: the cellulose is 3-7:

1.

4. The coating according to claim 3, characterized in that The amount of the silica sol is 17-18 parts.

5. The coating according to claim 4, characterized in that The amount of bentonite is 12-16 parts.

6. The coating according to claim 5, characterized in that The epoxy resin is present in an amount of 18 to 25 parts.

7. The coating according to claim 1, characterized in that The epoxy resin is selected from one of glycidyl ether epoxy resin, glycidyl ester epoxy resin or glycidyl amine epoxy resin.

8. The coating according to claim 1, characterized in that The coating further comprises 1-2 parts of an auxiliary agent by weight, and the auxiliary agent comprises a defoaming agent.

9. A method for preparing an aluminum alloy 3D printing photosensitive resin mold investment casting coating, characterized in that: The preparation method uses the coating component according to any one of claims 1 to 8, and the preparation method comprises the following steps: Mixing active magnesium oxide into silica sol according to a set ratio to obtain a first mixture; mixing bentonite and cellulose into epoxy resin in a set ratio to obtain a second mixture; The first mixture is mixed into the second mixture to obtain a coating.

10. The preparation method according to claim 9, characterized in that The mixing temperature of the first mixture is 20-40°C and the mixing speed is 1500-2000 rpm, the mixing temperature of the second mixture is 20-40°C and the mixing speed is 1000-3000 rpm, and the mixing temperature of the coating is 20-40°C and the mixing speed is 2000-3000 rpm.

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