Alcohol-based paint for water glass sand cast steel parts and preparation method thereof

Abstract

The application discloses a kind of alcohol-based paint for water glass sand cast steel and its preparation method, the paint includes: aggregate, suspending agent, binder, penetrant, additive and ethanol;The mass ratio of each component is as follows: aggregate: 60%-65%;Suspending agent: 4%-4.5%;Binder: 4%-4.5%;Penetrant: 1%-3%;Additive: 0.4%-1.5%;Ethanol: 28%-30%;Aggregate is composed of high bauxite powder, mullite powder, sillimanite powder, brown corundum powder, chromite powder, magnesium aluminate spinel;Suspending agent includes lithium-based bentonite and polyvinyl butyral, binder uses thermoplastic phenolic resin and rosin;Penetrant uses fatty alcohol polyoxyethylene ether, other additives include sodium pyrophosphate and trimethyl stearamide chloride.The paint prepared by the application has good brushability, long brushable distance after one-time dipping, and is easy to brush;It has good suspending property, and the refractory filler is uniformly suspended in the medium without sedimentation, delamination or caking;The coating is uniform, and the combustion is stable and sufficient when ignited and dried without blistering.

Description

Technical Field

[0001] This invention relates to an alcohol-based coating for water glass sand cast steel parts and its preparation method, belonging to the field of casting coatings. Background Technology

[0002] In the casting production process, coatings play a very important role. Their main functions are: (1) They can form a barrier with higher density, fire resistance and thermochemical stability on the surface of the mold (core), which can effectively prevent the penetration of molten metal or thermochemical reaction, thereby preventing the mechanical and chemical adhesion of castings and reducing the amount of cleaning work; (2) The surface of the mold (core) coated with coatings is smoother and denser and is not easily wetted by molten metal, which can improve the surface roughness grade of castings; (3) They improve the erosion resistance of the mold (core), reduce the heat radiation of molten metal to the sand mold, and prevent or reduce defects such as sand holes or sand inclusions in castings caused by sand erosion or thermal expansion.

[0003] In the production of water glass sand cast steel parts, zircon powder coatings are commonly used to achieve the above-mentioned purposes. However, the price of zircon powder coatings is significantly higher than other types of coatings, and the large-scale use of zircon powder coatings will significantly increase the production cost of castings. This invention provides a coating that can effectively replace zircon powder coatings and significantly reduce the cost of coatings, thereby lowering the production cost of castings. Summary of the Invention

[0004] The present invention aims to provide an alcohol-based coating that can effectively replace zircon powder coatings, suitable for the production of water glass sand cast steel parts, and has better overall performance in terms of effectiveness and economy.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides an alcohol-based coating for water glass sand cast steel parts, comprising: aggregate, suspending agent, binder, penetrant, additives and ethanol; the mass ratio of each component is as follows: aggregate: 60%-65%; suspending agent: 4%-4.5%; binder: 4%-4.5%; penetrant: 1%-3%; additives: 0.4%-1.5%; ethanol: 28%-30%.

[0006] Furthermore, the refractory filler (i.e., aggregate) of the coating is composed of high-alumina bauxite powder, mullite powder, sillimanite powder, brown corundum powder, chromite powder, and magnesium aluminum spinel; the mass ratio of high-alumina bauxite powder, mullite powder, sillimanite powder, brown corundum powder, chromite powder, and magnesium aluminum spinel is 40-70∶6-30∶4-15∶3.5-15∶3-10∶2-15.

[0007] The coating uses ethanol as a carrier, which can be ignited and dried, has a moderate burning rate, and is non-toxic and odorless. The suspending agent for the coating is lithium-based bentonite and polyvinyl butyral, with a mass ratio of 2.5-3.5:1-2.5. The binder for the coating is thermoplastic phenolic resin and rosin; the mass ratio of the two is 1.5-3:0.5-1.5. The penetrant used in the coating is fatty alcohol polyoxyethylene ether; Other additives for the coating: sodium pyrophosphate and trimethylstearamide chloride, with a mass ratio of 0.2-1.5:0.1-1.

[0008] The aggregates in this invention include high-alumina bauxite powder, mullite powder, sillimanite powder, brown corundum powder, chromite powder, and magnesium aluminum spinel. High-alumina bauxite powder is abundant and free from silica dust and radioactive hazards. Before grinding, the raw bauxite ore undergoes thorough calcination at 1300-1500℃, effectively preventing coating cracking and casting porosity defects. High-alumina bauxite powder has high refractoriness, stable thermal properties, and is not easily reacted with metal oxides to produce low-melting-point substances. It is also not easily wetted by molten metal or metal oxides, and its material cost is significantly lower than zircon powder. Mullite powder is a product obtained by sintering natural mullite concentrate at 1600℃. It has high purity, good performance, and is inexpensive, making it suitable as a refractory filler for coatings, with a refractoriness greater than 1850℃. Magnesium aluminum spinel is a novel synthetic refractory material with excellent properties such as a low coefficient of thermal expansion, strong resistance to chemical corrosion, good thermal conductivity, and high melting point. When formulated into coatings according to the proportions provided in this invention, it synergistically interacts with high-alumina bauxite powder, mullite powder, and sillimanite powder, exhibiting superior suspension, leveling, and brushability compared to other types of coatings. Chromite powder has high refractoriness, good thermal stability, strong resistance to alkaline slag, does not chemically react with iron oxides, is not wetted by molten metal, and has a thermal conductivity many times greater than silica sand. During the pouring of molten metal, the chromite powder in the coating undergoes solid-phase sintering, which helps improve the coating's resistance to sand adhesion and makes it easier to peel off the casting during cleaning.

[0009] Furthermore, suspending agents are used in coatings to form stable colloidal systems, ensuring uniform composition and preventing sedimentation and stratification during use, storage, or transportation. They also prevent the carrier from detaching from the refractory filler and penetrating the molding (core) sand independently. Suspension agents play a decisive role in the rheological properties and processing performance of coatings. Currently, most alcohol-based coatings used for cast steel parts in China employ organobentonite as a suspending agent, but organobentonite is expensive, significantly increasing coating costs. This invention uses lithium-based bentonite as a suspending agent, which has a strong suspending effect and is much cheaper than organobentonite. The polyvinyl butyral used in this invention also has a suspending effect, further enhancing the suspension performance of the coating.

[0010] This invention provides a method for preparing the above-mentioned alcohol-based coating for water glass sand cast steel parts, the specific steps of which are as follows: Step 1: Preparation of aggregate: Put high-alumina bauxite powder (40%-70%), mullite powder (10%-30%), sillimanite powder (5%-15%), brown corundum powder (5%-15%), chromite powder (5%-10%), and magnesium aluminum spinel (3%-15%) into a colloid mill for pulverization (particle size 200-300 mesh), grind, and mix thoroughly to obtain aggregate; Step 2: Preparation of the suspending agent: (1) The lithium-based bentonite is activated using the following process: I. Dry the lithium-based bentonite to a moisture content of less than 15% and pulverize it to (100-200) mesh.

[0011] II. Acidification. Activation is performed using hydrochloric acid at a dosage of (300-600) kg / 100 kg lithium-based bentonite, at an activation temperature of (50-100) ℃, for a time of (2-8) h. Continuous stirring is required during activation.

[0012] III. Washing. After activation, wash repeatedly with water until the washing solution is neutral. To accelerate sedimentation, an appropriate amount of high-efficiency flocculant polyacrylamide can be added. The dosage of flocculant is 0.01 kg / 100 kg lithium-based bentonite.

[0013] IV. Filtration. A pressure filtration process is used to remove most of the water from the washed activated clay slurry.

[0014] V. Drying. The moisture content of the product after drying must be less than 8%.

[0015] (2) Mix lithium-based bentonite, polyvinyl butyral, and ethanol in a ratio of (1.6-2):1:(1.6-2) and stir evenly to obtain a suspending agent. The suspending agent needs to be left for 36 hours before it can be used. Step 3: Thoroughly mix the binder, suspending agent, and ethanol; then add the aggregate and penetrant, and mix thoroughly; then add sodium pyrophosphate and trimethylstearamide chloride, and mix thoroughly to obtain the alcohol-based coating.

[0016] The coating prepared by this invention has good brushability, with a long brushing distance after a single dip, and is easy to apply; it has good suspension properties, with the refractory filler uniformly suspended in the medium without sedimentation, stratification, or clumping; the coating is uniform, and it burns steadily and completely during ignition and drying without bubbling.

[0017] This invention provides a method for applying alcohol-based coatings to the above-mentioned water glass sand cast steel parts, the specific steps of which are as follows: Step 1: Smooth out any protrusions on the surface of the sand core and clean away any loose sand.

[0018] Step 2: Stir the coating thoroughly until it is evenly mixed.

[0019] Step 3: Use a soft brush to fully dip into the paint and apply it to the sand core. Apply the paint in one direction only, and ignite it immediately after painting.

[0020] The beneficial effects of this invention are: (1) The high-alumina bauxite powder added in this invention has high refractoriness, stable thermal performance, is not easy to form low-melting-point substances with metal oxides, and is not easy to be wetted by molten metal and metal oxides. It is also cheaper than zircon powder. (2) Mullite powder is a high-performance refractory filler. The mullite powder added in this invention is sintered mullite, which is a product made by sintering natural mullite concentrate at a high temperature of 1600℃. It is inexpensive and its purity and performance are similar to those of fused mullite. (3) The magnesium aluminum spinel added in this invention has excellent properties such as small thermal expansion coefficient, strong resistance to chemical corrosion, good thermal conductivity and high melting point. When the coating is prepared according to the addition ratio provided in this invention, it works synergistically with high alumina bauxite powder, mullite powder and sillimanite powder, and has excellent suspension, leveling and brushability compared with other types of coatings. (4) The present invention uses lithium-based bentonite as a suspending agent, which has a strong suspending effect and is much cheaper than organic bentonite; the polyvinyl butyral used has a suspending effect and can enhance the suspension performance of the coating; therefore, the coating prepared by the present invention has good suspension properties and no sedimentation or stratification during use, storage and transportation. (5) The present invention uses a mixture of rosin and thermoplastic phenolic resin as a binder for coatings, which has good bonding strength, the coating is not easy to crack, the price is low, and the surface of the casting is smooth.

[0021] (6) The coating described in this invention has good brushability, and the brushing operation is time-saving and labor-saving; (7) The coating described in this invention burns stably when ignited and dried, without bubbling, and burns completely without any localized areas that are not fully dried. Detailed Implementation

[0022] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments.

[0023] This invention provides an alcohol-based coating for water glass sand cast steel parts, comprising: aggregate, suspending agent, binder, penetrant, additives and ethanol; the mass ratio of each component is as follows: aggregate: 60%-65%; suspending agent: 4%-4.5%; binder: 4%-4.5%; penetrant: 1%-3%; additives: 0.4%-1.5%; ethanol: 28%-30%.

[0024] The aggregates include high-alumina bauxite powder, mullite powder, sillimanite powder, brown corundum powder, chromite powder, and magnesium aluminum spinel; the penetrant is fatty alcohol polyoxyethylene ether. Examples 1 to 5 provide five experimental formulations. The proportions of each component of the coating in Examples 1 to 5 are shown in Table 1.

[0025] Table 1. Composition ratio of alcohol-based coatings (wt%)

[0026] The above Examples 1-5 were prepared using the following preparation method.

[0027] This invention provides a method for preparing the above-mentioned alcohol-based coating for water glass sand cast steel parts, the specific steps of which are as follows: Step 1: Preparation of aggregate: Put high-alumina bauxite powder, mullite powder, sillimanite powder, brown corundum powder, chromite powder, and magnesium aluminum spinel into a colloid mill for crushing (particle size of 200-300 mesh), grinding, and mixing thoroughly to obtain aggregate; Step 2: Preparation of the suspending agent: (1) The lithium-based bentonite is activated using the following process: I. Dry the bentonite to a moisture content of less than 15% and pulverize it to 100-200 mesh.

[0028] II. Acidification. Activation is performed using hydrochloric acid at a dosage of 300-600 kg / 100 kg, at a temperature of 50-100℃, for 2-8 hours. Continuous stirring is required during activation.

[0029] III. Washing. After activation, wash repeatedly with water until the washing solution is neutral. To accelerate sedimentation, an appropriate amount of high-efficiency flocculant polyacrylamide can be added during the process.

[0030] IV. Filtration. A pressure filtration process is used to remove most of the water from the washed activated clay slurry.

[0031] V. Drying. The moisture content of the product after drying must be less than 8%.

[0032] (2) Mix lithium-based bentonite, polyvinyl butyral and ethanol in a mass ratio of 1.6:1:1.8 and stir evenly to obtain a suspending agent. The suspending agent needs to be left for 36 hours before it can be used. Step 3: Thoroughly mix the binder, suspending agent, and remaining ethanol; then add the aggregate and penetrant, and mix thoroughly; finally add sodium pyrophosphate and trimethylstearamide chloride, and mix thoroughly to obtain the alcohol-based coating.

[0033] In Example 1: The suspending agent is lithium-based bentonite and polyvinyl butyral, with a mass ratio of 2.7:1.6. Binder: thermoplastic phenolic resin and rosin; the mass ratio of the two is 2.7:1.3; Additives: sodium pyrophosphate and trimethylstearamide chloride, in a mass ratio of 0.25:0.15.

[0034] The process for preparing the suspension is as follows: (1) The lithium-based bentonite is activated using the following process: I. Dry the bentonite to a moisture content of less than 15% and then pulverize it to 200 mesh.

[0035] II. Acidification. Activation is performed using hydrochloric acid at a rate of 360 kg / 100 kg, at a temperature of 100°C for 3 hours. Continuous stirring is required during activation.

[0036] III. Washing. After activation, wash repeatedly with water until the washing solution is neutral. To accelerate sedimentation during the process, high-efficiency flocculant polyacrylamide can be added at a rate of 0.01 kg / 100 kg.

[0037] IV. Filtration. A pressure filtration process is used to remove most of the water from the washed activated clay slurry.

[0038] V. Drying. The moisture content of the product after drying must be less than 8%.

[0039] (2) Mix lithium-based bentonite, polyvinyl butyral and ethanol in a mass ratio of 1.7:1:2 and stir evenly to obtain a suspending agent. The suspending agent needs to be left for 36 hours before it can be used.

[0040] The remaining ethanol is added in step three.

[0041] In Example 2: The suspending agent is lithium-based bentonite and polyvinyl butyral, with a mass ratio of 3:1.6. Binder: thermoplastic phenolic resin and rosin; the mass ratio of the two is 2.75:1.35; Additives: sodium pyrophosphate and trimethylstearamide chloride, in a mass ratio of 0.25:0.25; The process for preparing the suspension is as follows: (1) The lithium-based bentonite is activated using the following process: I. Dry the bentonite to a moisture content of less than 15% and then pulverize it to 200 mesh.

[0042] II. Acidification. Activation is performed using hydrochloric acid at a rate of 360 kg / 100 kg, at a temperature of 100°C for 3 hours. Continuous stirring is required during activation.

[0043] III. Washing. After activation, wash repeatedly with water until the washing solution is neutral. To accelerate sedimentation during the process, high-efficiency flocculant polyacrylamide can be added at a rate of 0.01 kg / 100 kg.

[0044] IV. Filtration. A pressure filtration process is used to remove most of the water from the washed activated clay slurry.

[0045] V. Drying. The moisture content of the product after drying must be less than 8%.

[0046] (2) Mix lithium-based bentonite, polyvinyl butyral and ethanol in a mass ratio of 1.75:1:1.85 and stir evenly to obtain a suspending agent. The suspending agent needs to be left for 36 hours before it can be used.

[0047] In Example 3: The suspending agent is lithium-based bentonite and polyvinyl butyral, with a mass ratio of 3:1.6. Binder: thermoplastic phenolic resin and rosin; the mass ratio of the two is 2.8:1.4; Additives: sodium pyrophosphate and trimethylstearamide chloride, in a mass ratio of 0.25:0.25; The process for preparing the suspension is as follows: (1) The lithium-based bentonite is activated using the following process: I. Dry the bentonite to a moisture content of less than 15% and then pulverize it to 200 mesh.

[0048] II. Acidification. Activation is performed using hydrochloric acid at a rate of 360 kg / 100 kg, at a temperature of 100°C for 3 hours. Continuous stirring is required during activation.

[0049] III. Washing. After activation, wash repeatedly with water until the washing solution is neutral. To accelerate sedimentation during the process, high-efficiency flocculant polyacrylamide can be added at a rate of 0.01 kg / 100 kg.

[0050] IV. Filtration. A pressure filtration process is used to remove most of the water from the washed activated clay slurry.

[0051] V. Drying. The moisture content of the product after drying must be less than 8%.

[0052] (2) Mix lithium-based bentonite, polyvinyl butyral and ethanol in a mass ratio of 1.7:1:1.8 and stir evenly to obtain a suspending agent. The suspending agent needs to be left for 36 hours before it can be used.

[0053] In Example 4: The suspending agent is lithium-based bentonite and polyvinyl butyral, with a mass ratio of 3:1.67. Binder: thermoplastic phenolic resin and rosin; the mass ratio of the two is 2.75:1.35; Additives: sodium pyrophosphate and trimethylstearamide chloride, in a mass ratio of 0.26:0.14; The process for preparing the suspension is as follows: (1) The lithium-based bentonite is activated using the following process: I. Dry the bentonite to a moisture content of less than 15% and then pulverize it to 200 mesh.

[0054] II. Acidification. Activation is performed using hydrochloric acid at a rate of 360 kg / 100 kg, at a temperature of 100°C for 3 hours. Continuous stirring is required during activation.

[0055] III. Washing. After activation, wash repeatedly with water until the washing solution is neutral. To accelerate sedimentation during the process, high-efficiency flocculant polyacrylamide can be added at a rate of 0.01 kg / 100 kg.

[0056] IV. Filtration. A pressure filtration process is used to remove most of the water from the washed activated clay slurry.

[0057] V. Drying. The moisture content of the product after drying must be less than 8%.

[0058] (2) Mix lithium-based bentonite, polyvinyl butyral and ethanol in a mass ratio of 2:1:1.8 and stir evenly to obtain a suspending agent. The suspending agent needs to be left for 36 hours before it can be used.

[0059] In Example 5: The suspending agent is lithium-based bentonite and polyvinyl butyral, with a mass ratio of 3:1.58. Binder: thermoplastic phenolic resin and rosin; the mass ratio of the two is 2.79:1.41; Additives: sodium pyrophosphate and trimethylstearamide chloride, in a mass ratio of 0.27:0.13; The process for preparing the suspension is as follows: (1) The lithium-based bentonite is activated using the following process: I. Dry the bentonite to a moisture content of less than 15% and then pulverize it to 200 mesh.

[0060] II. Acidification. Activation is performed using hydrochloric acid at a rate of 360 kg / 100 kg, at a temperature of 100°C for 3 hours. Continuous stirring is required during activation.

[0061] III. Washing. After activation, wash repeatedly with water until the washing solution is neutral. To accelerate sedimentation during the process, high-efficiency flocculant polyacrylamide can be added at a rate of 0.01 kg / 100 kg.

[0062] IV. Filtration. A pressure filtration process is used to remove most of the water from the washed activated clay slurry.

[0063] V. Drying. The moisture content of the product after drying must be less than 8%.

[0064] (2) Mix lithium-based bentonite, polyvinyl butyral and ethanol in a mass ratio of 1.9:1:2 and stir evenly to obtain a suspending agent. The suspending agent needs to be left for 36 hours before it can be used.

[0065] Implementation effect

[0066] 1. The coatings prepared in this invention are tested according to "JB / T9226 Coatings for Sand Casting". The performance indicators of the alcohol-based coatings in Examples 1-5 are shown in Table 2.

[0067] Table 2 Coating Performance Indicators

[0068] 2. The appearance of the alcohol-based coatings prepared in Examples 1-5 was inspected. The coatings were uniform, and the combustion was stable and complete when ignited and dried, without any bubbling.

[0069] 3. The coating prepared by this invention can seal a large number of pores on the surface of the core, providing a barrier with higher density, fire resistance and thermochemical stability, effectively preventing the penetration of molten metal or thermochemical reaction, preventing the mechanical and chemical adhesion of castings, and reducing the amount of cleaning work required for castings.

Claims

1. An alcohol-based coating for water glass sand cast steel parts, characterized in that... include: Aggregates, suspending agents, binders, penetrants, additives, and ethanol; the mass ratio of each component is as follows: Aggregates: 60%-65%; Suspension agent: 4%-4.5%; binder: 4%-4.5%; penetrant: 1%-3%; additives: 0.4%-1.5%; ethanol: 28%-30%; the aggregate is composed of high-alumina bauxite powder, mullite powder, sillimanite powder, brown corundum powder, chromite powder, and magnesium aluminum spinel, with a mass ratio of 40-70:6-30:4-15:3.5-15:3-10:2-15; the binder is thermoplastic phenolic resin and rosin, with a mass ratio of 1.5-3:0.5-1.5; the additives include sodium pyrophosphate and trimethylstearamide chloride, with a mass ratio of 0.2-1.5:0.1-1; The suspending agent comprises lithium-based bentonite and polyvinyl butyral; the preparation process of the suspending agent is as follows: (1) The lithium-based bentonite is activated using the following process: I. Dry the lithium-based bentonite to a moisture content of less than 15% and pulverize it to 100-200 mesh; II. Acidification: Activation is carried out using hydrochloric acid at a dosage of 300-600 kg / 100 kg lithium-based bentonite. The activation temperature is 50-100℃, and the activation time is 2-8 hours. Continuous stirring is required during activation. III. Washing: After activation, wash with water multiple times until the washing solution is neutral; during the process, add an appropriate amount of high-efficiency flocculant polyacrylamide to accelerate sedimentation; IV. Filtration: Pressure filtration is used to remove most of the water from the washed activated clay slurry; V. Drying: The moisture content of the product after drying must be less than 8%; (2) Mix lithium-based bentonite, polyvinyl butyral and ethanol in a mass ratio of 1.6-2:1:1.6-2 and stir evenly to obtain a suspending agent. The suspending agent needs to be left for 36 hours before it can be used.

2. The alcohol-based coating for water glass sand cast steel parts according to claim 1, characterized in that: The penetrant used in the coating is fatty alcohol polyoxyethylene ether.

3. A method for preparing an alcohol-based coating for water glass sand cast steel parts according to any one of claims 1 to 2, characterized in that... The specific steps are as follows: Step 1: Preparation of aggregate: Put high-alumina bauxite powder, mullite powder, sillimanite powder, brown corundum powder, chromite powder, and magnesium aluminum spinel into a colloid mill and grind them to a particle size of 200-300 mesh. Grind, mix and stir thoroughly to obtain aggregate. Step 2: Preparation of the suspending agent: (1) The lithium-based bentonite is activated using the following process: I. Dry the lithium-based bentonite to a moisture content of less than 15% and pulverize it to 100-200 mesh; II. Acidification: Activation is carried out using hydrochloric acid at a dosage of 300-600 kg / 100 kg lithium-based bentonite. The activation temperature is 50-100℃, and the activation time is 2-8 hours. Continuous stirring is required during activation. III. Washing: After activation, wash with water multiple times until the washing solution is neutral; during the process, add an appropriate amount of high-efficiency flocculant polyacrylamide to accelerate sedimentation; IV. Filtration: Pressure filtration is used to remove most of the water from the washed activated clay slurry; V. Drying: The moisture content of the product after drying must be less than 8%; (2) Mix lithium-based bentonite, polyvinyl butyral and ethanol in a mass ratio of 1.6-2:1:1.6-2 and stir evenly to obtain a suspending agent. The suspending agent needs to be left for 36 hours before it can be used. Step 3: Thoroughly mix the binder, suspending agent, and ethanol; then add the aggregate and penetrant, and mix thoroughly; then add sodium pyrophosphate and trimethylstearamide chloride, and mix thoroughly to obtain the alcohol-based coating.

4. A method for applying an alcohol-based coating to water glass sand cast steel parts according to any one of claims 1 to 2, characterized in that... The specific steps are as follows: Step 1: Smooth out the protrusions on the surface of the sand core and clean the loose sand from the surface of the sand core. Step 2: Stir the coating thoroughly until it is evenly mixed; Step 3: Use a soft brush to fully dip into the paint and apply it to the sand core. Apply the paint in one direction only, and ignite it immediately after painting.

Images