Low-viscosity high-density water-based talc tape casting slurry and preparation method thereof

Abstract

The invention relates to the technical field of sealing materials, and discloses low-viscosity high-density water-based talc tape casting slurry and a preparation method thereof.The water-based talc tape casting slurry is prepared from acidified talcum powder, a composite dispersing agent, a water-based adhesive and water, and the composite dispersing agent is composed of a polycarboxylate dispersing agent and a phosphate dispersing agent; the tape-casting slurry adopts acidified talcum powder and a composite dispersant, the acidified talcum powder is prepared by acidizing talcum powder, the acidizing treatment can remove carbonate impurities and form silicon hydroxyl on the surface of the talcum powder, so that the high-temperature performance and hydrophilicity of the talcum powder are enhanced, and the composite dispersant is prepared by compounding polycarboxylate and phosphate. The composite dispersant can significantly reduce the viscosity of the slurry; the method is simple in process, low in energy consumption, small in organic solvent dosage and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing materials, and in particular to a low-viscosity and high-density water-based talc casting slurry and a preparation method thereof. Background Art

[0002] With the development of industrial technology towards extreme environments, high-temperature working conditions (such as aerospace, energy chemistry, solid oxide fuel cells) have strict requirements for the heat resistance (≥800 °C) of sealing materials. Talc, due to its high melting point (about 1550 °C), lubricity and chemical stability brought by its lamellar structure, has become one of the choices for preparing high-temperature resistant sealing materials. In the prior art, most talc-based sealing materials are organic systems and the treatment process is complex, with problems such as high production risk, large environmental pollution and complex process. For example, a talc-based high-temperature resistant sealing material and its preparation method disclosed in CN115537181A. In this method, talc, glass fiber, adhesive, etc. are ball-milled to make a slurry, and then the sealing material is prepared by a casting forming method. The talc in this method also needs to be pretreated such as calcination, modification, impregnation, etc. before use, with defects such as complex process flow, high risk of safe production and large environmental pollution. Therefore, there is an urgent need for an environmentally friendly and simple process for preparing talc-based casting slurry.

[0003] A water-based casting slurry with ceramic powder as the main phase and water as the solvent is disclosed in the prior art. This casting slurry has the advantages of environmental protection, safety and low cost. Therefore, the present invention envisions using talc as the main phase to provide a water-based talc casting slurry for high-temperature sealing. However, when the present invention verifies this idea, it is found that the following problems exist in the preparation of the water-based talc casting slurry for high-temperature sealing: (1) Talc is a layered magnesium silicate mineral, and its surface is mainly composed of non-polar silicon-oxygen tetrahedrons and magnesium-oxygen octahedrons, lacking hydrophilic groups, showing lipophilic and hydrophobic properties, making it difficult to disperse in the water-based system. (2) Natural talc ore usually contains carbonate impurities such as dolomite. These carbonate impurities are easily decomposed under high-temperature conditions, which will greatly reduce its high-temperature applications. (3) Using small-particle-size talc particles can improve the density of the formed material, but reducing the particle size will cause a significant increase in the viscosity of the casting slurry, resulting in problems in casting. Therefore, how to solve the above problems is of great significance for the preparation of water-based talc casting slurry for high-temperature sealing. Summary of the Invention

[0004] The present invention aims at the problems of water-based talc casting slurry for high-temperature sealing, such as difficult dispersion of talc in water, many high-temperature intolerant impurities in talc, and high viscosity of small-particle talc slurry, and provides a low-viscosity and high-density water-based talc casting slurry and a preparation method thereof. Acidified talc powder and a composite dispersant are adopted in the casting slurry. The acidified talc powder is made by acidifying talc powder. The acidification treatment can remove carbonate impurities and form silanol groups on the surface of talc powder, enhancing the high-temperature performance and hydrophilicity of talc powder. The composite dispersant is prepared by compounding polycarboxylate and phosphate ester. The composite dispersant can significantly reduce the viscosity of the slurry.

[0005] The specific technical solution of the present invention is as follows: A low-viscosity and high-density water-based talc casting slurry, the raw materials of which include, by mass, acidified talc powder, 1-2 parts of a composite dispersant, 3-5 parts of a water-based adhesive, and 25-35 parts of water. The composite dispersant is composed of a polycarboxylate dispersant and a phosphate ester dispersant.

[0006] Preferably, the mass ratio of the polycarboxylate dispersant to the phosphate ester dispersant is 1.5-2:1 Preferably, the polycarboxylate dispersant is sodium polyacrylate, and the phosphate ester dispersant is triethyl phosphate.

[0007] Preferably, the water-based adhesive is one or more of styrene-acrylic emulsion, styrene-butadiene emulsion, and acrylic emulsion.

[0008] Preferably, the raw materials further include a plasticizer, and the plasticizer is polyethylene glycol.

[0009] The present invention provides a low-viscosity and high-density water-based talc casting slurry. Acidified talc powder and a composite dispersant are adopted in the raw materials of the casting slurry. The acidified talc powder is made by acidifying talc powder with acid solution. Silanol groups (Si-OH) will be formed on the surface of the prepared acidified talc powder, which can significantly enhance hydrophilicity and solve the problem of poor dispersion of talc in water. After acidification treatment, the acidified talc powder can remove carbonate impurities of dolomite in talc, avoid the decomposition of talc to produce pores in a high-temperature environment, and improve the high-temperature resistance of talc powder, thus solving the problem of poor high-temperature resistance of talc powder. The composite dispersant in the present invention is prepared by compounding a polycarboxylate dispersant and a phosphate ester dispersant. The polycarboxylate dispersant disperses particles through steric hindrance effect, and the phosphate ester dispersant stabilizes the slurry through electrostatic repulsion. The two cooperate to reduce the viscosity of the water-based talc casting slurry, solving the problems of high viscosity and difficult casting of small-particle talc casting slurry. The low-viscosity and high-density water-based talc casting slurry of the present invention adopts a water-based system without toxic solvents, and the production cost is reduced by 25% compared with the traditional organic system. When the casting slurry is cured and applied in the sealing field, the temperature resistance can reach above 1000°C.

[0010] The adhesive of the present invention uses a water-based adhesive, reducing the use of organic solvents and further enhancing the environmental performance of the casting slurry.

[0011] A preparation method of the above-mentioned low-viscosity and high-density water-based talc casting slurry includes the following steps: (1) Mix coarse-particle talc powder, medium-particle talc powder, and fine-particle talc powder and then perform ball milling to produce multi-stage talc powder; (2) Soak the multi-stage talc powder in an acid solution for acidification treatment to produce acidified talc powder; (3) Ultrasonically disperse the acidified talc powder, composite dispersant, and deionized water to produce a mixed solution, and then add a water-based adhesive and a plasticizer to the mixed solution for stirring and vacuum defoaming to produce a low-viscosity and high-density water-based talc casting slurry.

[0012] Preferably, the mass ratio of the coarse-particle talc powder, medium-particle talc powder, and fine-particle talc powder is 50-60:20-30:10-20.

[0013] Preferably, the D50 of the coarse-particle talc powder is 14-16 μm, the D50 of the medium-particle talc powder is 6-7 μm, and the D50 of the fine-particle talc powder is 2-3 μm.

[0014] Preferably, the conditions of the ultrasonic dispersion treatment include: ultrasonic frequency 30-50 kHz, ultrasonic power 750-850 w, and rotation speed 800-1000 rpm.

[0015] Preferably, the acid solution is a 1-3 mol / L hydrochloric acid solution.

[0016] Preferably, the conditions of the acidification treatment include: temperature 60-80 °C, reaction time 2-4 h, rotation speed 400-500 rpm, and wash to neutral after acidification.

[0017] Preferably, the vacuum degree of the vacuum defoaming treatment is -0.01 to -0.09 MPa.

[0018] The present invention also provides a method for preparing the above-mentioned low-viscosity and high-density water-based talc casting slurry. In this method, talc powders of three particle size levels, namely coarse particle talc powder, medium particle talc powder, and fine particle talc powder, are used for multi-scale grading design. The coarse particle talc powder can form a skeleton, and the medium particle talc powder and the fine particle talc powder can fill the gaps in the skeleton, forming a dense packing structure, significantly increasing the solid content of the slurry, and further improving the curing density after the casting slurry is cured. In this method, an acid solution is also used to acidify and ultrasonically disperse the talc powder. The acidification treatment can remove carbonate impurities in the talc and improve the hydrophilicity of the talc surface. Ultrasonic dispersion can exfoliate the talc lamellae and improve the dispersion efficiency. Using the acidification treatment and ultrasonic dispersion treatment, the process flow time can be shortened by more than 30% compared with the existing talc powder calcination, impregnation, and modification steps. The above method disclosed by the present invention has the characteristics of simple process, low energy consumption, and environmental protection.

[0019] Compared with the prior art, the present application has the following technical effects: (1) The present invention uses a composite dispersant made of a polycarboxylate dispersant and a phosphate ester dispersant. This composite dispersant can synergistically reduce the viscosity of the water-based talc casting slurry, solving the problem of high viscosity of the small particle water-based talc casting slurry.

[0020] (2) In the present invention, the acidified talc powder adopts multi-scale powder grading of coarse particles, medium particles, and fine particles to form a dense packing structure, which can significantly increase the solid content of the slurry and improve the curing density of the casting slurry.

[0021] (3) The present invention uses an acid solution to acidify the talc powder to make acidified talc powder, removing carbonate impurities in the talc powder and at the same time improving the hydrophilicity of the talc surface, increasing the dispersibility of the talc powder in water, and solving the problems of poor high-temperature resistance and poor water dispersibility of the talc powder.

[0022] (4) In the preparation method of the present invention, the combination of acidification treatment and ultrasonic dispersion treatment is adopted. Compared with the traditional calcination, impregnation, and modification processes, the operation is simple and the process flow is short.

[0023] (5) The adhesive in the present invention uses a water-based adhesive. Compared with the traditional polyvinyl butyral adhesive, the amount of organic solvent used is small, and it is safe and environmentally friendly. Detailed Embodiments

[0024] The present invention will be further described below in conjunction with embodiments.

[0025] Example 1: A method for preparing a low-viscosity and high-density water-based talc casting slurry includes the following steps: (1) Inject coarse talc powder (D50 is 15 μm), medium talc powder (D50 is 6.5 μm), and fine talc powder (D50 is 2.5 μm) into a dry ball mill at a mass ratio of 60:25:15 and mix at a speed of 200 rpm for 30 min to make multi-stage talc powder; (2) Add the above multi-stage talc powder to the acid solution at a solid-liquid volume ratio of 3:1, magnetically stir and react for 3 h under the conditions of a rotation speed of 500 rpm and a temperature of 70 °C. After the reaction is completed, filter the liquid and wash the solid with deionized water until the pH is neutral to make acidified talc powder; (3) Add 100 parts of the above acidified talc powder, 2 parts of a composite dispersant (composed of 1.33 kg of sodium polyacrylate and 0.67 kg of triethyl phosphate), and 30 kg of deionized water to an ultrasonic magnetic stirring tank, and ultrasonically stir for 30 min under the conditions of an ultrasonic frequency of 40 kHz, an ultrasonic power of 800 w, and a stirring speed of 900 rpm to make a mixed solution; then transfer the mixed solution to an ultrasonic reactor and treat the mixed slurry for 30 min under certain conditions; then add 4 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) in sequence and stir at a speed of 500 rpm for 20 min to make a slurry, and then place the slurry under a vacuum degree of -0.095 MPa for vacuum degassing treatment for 15 min to make a low-viscosity high-density water-based talc casting slurry.

[0026] Example 2: A preparation method of a low-viscosity high-density water-based talc casting slurry, comprising the following steps: (1) Inject coarse talc powder (D50 is 14 μm), medium talc powder (D50 is 6 μm), and fine talc powder (D50 is 2 μm) into a dry ball mill at a mass ratio of 50:20:10 and mix at a speed of 200 rpm for 30 min to make multi-stage talc powder; (2) Add the above multi-stage talc powder to the acid solution at a solid-liquid volume ratio of 3:1, magnetically stir and react for 2 h under the conditions of a rotation speed of 500 rpm and a temperature of 60 °C. After the reaction is completed, filter the liquid and wash the solid with deionized water until the pH is neutral to make acidified talc powder; (3) Add 100 parts of the above acidified talc powder, 1.5 parts of a composite dispersant (2 kg of sodium polyacrylate and 1 kg of triethyl phosphate), and 25 parts of deionized water to an ultrasonic magnetic stirring tank, and ultrasonically stir for 30 min under the conditions of an ultrasonic frequency of 30 kHz, an ultrasonic power of 750 w, and a stirring speed of 800 rpm to make a mixed solution; then add 3 - 5 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) in sequence and stir at a speed of 500 rpm for 20 min to make a slurry, and then place the slurry under a vacuum degree of -0.1 MPa for vacuum degassing treatment for 15 min to make a low-viscosity high-density water-based talc casting slurry.

[0027] Example 3: A preparation method of a low-viscosity and high-density water-based talc casting slurry, comprising the following steps: (1) Coarse talc powder (D50 is 16 μm), medium talc powder (D50 is 7 μm), and fine talc powder (D50 is 3 μm) are injected into a dry ball mill according to a mass ratio of 60:30:20 and mixed at a rotation speed of 200 rpm for 30 min to make multi-stage talc powder; (2) The above multi-stage talc powder is added to the acid solution according to a solid-liquid volume ratio of 3:1, magnetically stirred and reacted at a rotation speed of 500 rpm and a temperature of 80 °C for 4 h. After the reaction is completed, the liquid is filtered and the solid is washed with deionized water until the pH is neutral to make acidified talc powder; (3) 100 parts of the above acidified talc powder, 1 part of a composite dispersant (1.5 kg of sodium polyacrylate and 1 kg of triethyl phosphate), and 35 parts of deionized water are added to an ultrasonic magnetic stirring tank and ultrasonically stirred for 30 min under the conditions of an ultrasonic frequency of 50 kHz, an ultrasonic power of 850 w, and a stirring rotation speed of 1000 rpm to make a mixed solution; then 5 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) are added in sequence and stirred at a rotation speed of 500 rpm for 20 min to make a slurry, and then the slurry is placed under a vacuum degree of -0.09 MPa for vacuum degassing treatment for 15 min to make a low-viscosity and high-density water-based talc casting slurry.

[0028] Example 4: A preparation method of a low-viscosity and high-density water-based talc casting slurry, comprising the following steps: (1) Coarse talc powder (D50 is 15 μm), medium talc powder (D50 is 6.5 μm), and fine talc powder (D50 is 2.5 μm) are injected into a dry ball mill according to a mass ratio of 60:25:15 and mixed at a rotation speed of 200 rpm for 30 min to make multi-stage talc powder; (2) The above multi-stage talc powder is added to the acid solution according to a solid-liquid volume ratio of 3:1, magnetically stirred and reacted at a rotation speed of 500 rpm and a temperature of 70 °C for 2 h. After the reaction is completed, the liquid is filtered and the solid is washed with deionized water until the pH is neutral to make acidified talc powder; (3) Add 100 parts of the above acidified talc powder, 2 parts of a composite dispersant (composed of 1.33 kg of sodium polyacrylate and 0.67 kg of triethyl phosphate), and 30 kg of deionized water into an ultrasonic magnetic stirring tank. Under the conditions of an ultrasonic frequency of 40 kHz, an ultrasonic power of 800 w, and a stirring speed of 900 rpm, ultrasonically stir for 30 min to prepare a mixed solution; then sequentially add 4 parts of a water-based adhesive (styrene-acrylic emulsion) and a plasticizer (polyethylene glycol 400) and stir at a speed of 500 rpm for 20 min to prepare a slurry. Then place the slurry under a vacuum degree of -0.095 MPa for vacuum degassing treatment for 15 min to prepare a low-viscosity and high-density water-based talc casting slurry.

[0029] Example 5: A method for preparing a low-viscosity and high-density water-based talc casting slurry, comprising the following steps: (1) Inject coarse-particle talc powder (D50 is 15 μm), medium-particle talc powder (D50 is 6.5 μm), and fine-particle talc powder (D50 is 2.5 μm) into a dry ball mill according to a mass ratio of 60:25:15 and mix at a speed of 200 rpm for 30 min to prepare multi-stage talc powder; (2) Add the above multi-stage talc powder to an acid solution according to a solid-liquid volume ratio of 3:1, magnetically stir and react at a speed of 500 rpm and a temperature of 70 °C for 4 h. After the reaction is completed, filter the liquid and wash the solid with deionized water until the pH is neutral to prepare acidified talc powder; (3) Add 100 parts of the above acidified talc powder, 2 parts of a composite dispersant (composed of 1.33 kg of sodium polyacrylate and 0.67 kg of triethyl phosphate), and 30 kg of deionized water into an ultrasonic magnetic stirring tank. Under the conditions of an ultrasonic frequency of 40 kHz, an ultrasonic power of 800 w, and a stirring speed of 900 rpm, ultrasonically stir for 30 min to prepare a mixed solution; then sequentially add 4 parts of a water-based adhesive (styrene-butadiene emulsion) and a plasticizer (polyethylene glycol 400) and stir at a speed of 500 rpm for 20 min to prepare a slurry. Then place the slurry under a vacuum degree of -0.095 MPa for vacuum degassing treatment for 15 min to prepare a low-viscosity and high-density water-based talc casting slurry.

[0030] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that no composite dispersant is used in Comparative Example 1; it includes the following steps: (1) Inject coarse-particle talc powder (D50 is 15 μm), medium-particle talc powder (D50 is 6.5 μm), and fine-particle talc powder (D50 is 2.5 μm) into a dry ball mill according to a mass ratio of 60:25:15 and mix at a speed of 200 rpm for 30 min to prepare multi-stage talc powder; (2) Add the above-mentioned multi-stage talcum powder to the acid solution at a solid-liquid volume ratio of 3:1, magnetically stir and react for 3 h at a rotation speed of 500 rpm and a temperature of 70 °C. After the reaction is completed, filter the liquid and wash the solid with deionized water until the pH is neutral to prepare acidified talcum powder; (3) Add 100 parts of the above-mentioned acidified talcum powder and 30 kg of deionized water to an ultrasonic magnetic stirring tank, and ultrasonically stir for 30 min under the conditions of an ultrasonic frequency of 40 kHz, an ultrasonic power of 800 w, and a stirring speed of 900 rpm to prepare a mixed solution; then sequentially add 4 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) and stir at a rotation speed of 500 rpm for 20 min to prepare a slurry, and then place the slurry under a vacuum degree of -0.095 MPa for vacuum degassing treatment for 15 min to prepare a low-viscosity and high-density water-based talc casting slurry.

[0031] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the composite dispersant in Comparative Example 2 is composed of 1.33 kg of sodium polyacrylate and 0.67 kg of deionized water; it includes the following steps: (1) Inject coarse-particle talcum powder (D50 is 15 μm), medium-particle talcum powder (D50 is 6.5 μm), and fine-particle talcum powder (D50 is 2.5 μm) into a dry ball mill at a mass ratio of 60:25:15 and mix at a rotation speed of 200 rpm for 30 min to prepare multi-stage talcum powder; (2) Add the above-mentioned multi-stage talcum powder to the acid solution at a solid-liquid volume ratio of 3:1, magnetically stir and react for 3 h at a rotation speed of 500 rpm and a temperature of 70 °C. After the reaction is completed, filter the liquid and wash the solid with deionized water until the pH is neutral to prepare acidified talcum powder; (3) Add 100 parts of the above-mentioned acidified talcum powder, 2 parts of a composite dispersant (composed of 1.33 kg of sodium polyacrylate and 0.67 kg of deionized water), and 30 kg of deionized water to an ultrasonic magnetic stirring tank, and ultrasonically stir for 30 min under the conditions of an ultrasonic frequency of 40 kHz, an ultrasonic power of 800 w, and a stirring speed of 900 rpm to prepare a mixed solution; then sequentially add 4 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) and stir at a rotation speed of 500 rpm for 20 min to prepare a slurry, and then place the slurry under a vacuum degree of -0.095 MPa for vacuum degassing treatment for 15 min to prepare a low-viscosity and high-density water-based talc casting slurry.

[0032] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the composite dispersant in Comparative Example 3 is composed of 1.33 kg of deionized water and 0.67 kg of triethyl phosphate, and it includes the following steps: (1) Coarsely grained talcum powder (D50 is 15 μm), medium grained talcum powder (D50 is 6.5 μm) and finely grained talcum powder (D50 is 2.5 μm) are injected into a dry ball mill at a mass ratio of 60:25:15 and mixed at a rotational speed of 200 rpm for 30 min to produce multi-stage talcum powder; (2) The above multi-stage talcum powder is added to the acid solution at a solid-liquid volume ratio of 3:1, and magnetically stirred and reacted for 3 h under the conditions of a rotational speed of 500 rpm and a temperature of 70 °C. After the reaction is completed, the liquid is filtered and the solid is washed with deionized water until the pH is neutral to produce acidified talcum powder; (3) 100 parts of the above acidified talcum powder, 2 parts of a composite dispersant (composed of 1.33 kg of deionized water and 0.67 kg of triethyl phosphate), and 30 kg of deionized water are added to an ultrasonic magnetic stirring tank and ultrasonically stirred for 30 min under the conditions of an ultrasonic frequency of 40 kHz, an ultrasonic power of 800 w, and a stirring rotational speed of 900 rpm to produce a mixed solution; then 4 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) are added in sequence and stirred at a rotational speed of 500 rpm for 20 min to produce a slurry, and then the slurry is subjected to vacuum degassing treatment at a vacuum degree of -0.095 MPa for 15 min to produce a low-viscosity and high-density water-based talcum casting slurry.

[0033] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that the talcum powder in Comparative Example 4 was not acidified, and it includes the following steps: (1) Coarsely grained talcum powder (D50 is 15 μm), medium grained talcum powder (D50 is 6.5 μm) and finely grained talcum powder (D50 is 2.5 μm) are injected into a dry ball mill at a mass ratio of 60:25:15 and mixed at a rotational speed of 200 rpm for 30 min to produce multi-stage talcum powder; (2) 100 parts of the above multi-stage talcum powder, 2 parts of a composite dispersant (composed of 1.33 kg of sodium polyacrylate and 0.67 kg of triethyl phosphate), and 30 kg of deionized water are added to an ultrasonic magnetic stirring tank and ultrasonically stirred for 30 min under the conditions of an ultrasonic frequency of 40 kHz, an ultrasonic power of 800 w, and a stirring rotational speed of 900 rpm to produce a mixed solution; then 4 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) are added in sequence and stirred at a rotational speed of 500 rpm for 20 min to produce a slurry, and then the slurry is subjected to vacuum degassing treatment at a vacuum degree of -0.095 MPa for 15 min to produce a low-viscosity and high-density water-based talcum casting slurry.

[0034] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that multi-stage talcum powder was not used, and all the talcum powder was coarsely grained talcum powder, including the following steps: (1) Add coarse talc powder (D50 is 15 μm) to the acid solution at a solid-liquid volume ratio of 3:1, and magnetically stir and react for 3 h at a rotation speed of 500 rpm and a temperature of 70 °C. After the reaction, filter the liquid and wash the solid with deionized water until the pH is neutral to make acidified talc powder; (2) Add 100 parts of the above acidified talc powder, 2 parts of a composite dispersant (composed of 1.33 kg of sodium polyacrylate and 0.67 kg of triethyl phosphate), and 30 kg of deionized water to an ultrasonic magnetic stirring tank, and ultrasonically stir for 30 min under the conditions of an ultrasonic frequency of 40 kHz, an ultrasonic power of 800 w, and a stirring speed of 900 rpm to make a mixed solution; then sequentially add 4 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) and stir at a rotation speed of 500 rpm for 20 min to make a slurry, and then place the slurry under a vacuum degree of -0.095 MPa for vacuum degassing treatment for 15 min to make a low-viscosity and high-density water-based talc casting slurry.

[0035] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that no multi-stage talc powder is used, and all the talc powder is fine-particle talc powder, including the following steps: (1) Add coarse talc powder (D50 is 2.5 μm) to the acid solution at a solid-liquid volume ratio of 3:1, and magnetically stir and react for 3 h at a rotation speed of 500 rpm and a temperature of 70 °C. After the reaction, filter the liquid and wash the solid with deionized water until the pH is neutral to make acidified talc powder; (2) Add 100 parts of the above acidified talc powder, 2 parts of a composite dispersant (composed of 1.33 kg of sodium polyacrylate and 0.67 kg of triethyl phosphate), and 30 kg of deionized water to an ultrasonic magnetic stirring tank, and ultrasonically stir for 30 min under the conditions of an ultrasonic frequency of 40 kHz, an ultrasonic power of 800 w, and a stirring speed of 900 rpm to make a mixed solution; then sequentially add 4 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) and stir at a rotation speed of 500 rpm for 20 min to make a slurry, and then place the slurry under a vacuum degree of -0.095 MPa for vacuum degassing treatment for 15 min to make a low-viscosity and high-density water-based talc casting slurry.

[0036] Comparative Example 7: The difference between Comparative Example 7 and Example 1 is that no ultrasonic dispersion treatment is carried out, including the following steps: (1) Inject coarse talc powder (D50 is 15 μm), medium-particle talc powder (D50 is 6.5 μm), and fine-particle talc powder (D50 is 2.5 μm) into a dry ball mill at a mass ratio of 60:25:15 and mix at a rotation speed of 200 rpm for 30 min to make multi-stage talc powder; (2) Add the above-mentioned multi-stage talcum powder to the acid solution at a solid-liquid volume ratio of 3:1, and magnetically stir and react for 3 h under the conditions of a rotation speed of 500 rpm and a temperature of 70 °C. After the reaction is completed, filter the liquid and wash the solid with deionized water until the pH is neutral to prepare acidified talcum powder; (3) Add 100 parts of the above-mentioned acidified talcum powder, 2 parts of a composite dispersant (composed of 1.33 kg of sodium polyacrylate and 0.67 kg of triethyl phosphate), and 30 kg of deionized water to a stirring tank, and stir at a high speed of 9000 rpm for 20 min to prepare a mixed solution; then sequentially add 4 parts of a water-based adhesive (acrylic emulsion) and a plasticizer (polyethylene glycol 400) and stir at a rotation speed of 500 rpm for 20 min to prepare a slurry. Then place the slurry under a vacuum degree of -0.095 MPa for vacuum defoaming treatment for 15 min to prepare a low-viscosity and high-density water-based talcum casting slurry.

[0037] Test Example 1: Test the properties of the low-viscosity and high-density water-based talcum casting slurries prepared in Examples 1 to 5 and Comparative Examples 1 to 7. The test items include: viscosity, solid content, cured density, and high-temperature resistance; The viscosity was tested according to the method disclosed in "QB / T 1545-2015 Determination Method for Relative Viscosity, Relative Fluidity and Thixotropy of Ceramic Slurries"; The solid content was tested according to the method disclosed in "GB / T 8077-2012 Test Methods for the Homogeneity of Concrete Admixtures"; The cured density was tested according to the method of "JB / T 9141.1-2013 Flexible Graphite Sheets Part 1 Density Test Method"; the high-temperature resistance was tested according to the method of "GB / T 27970-2011 Test Method for Burning Loss of Non-Metallic Gasket Materials"; The test results are shown in Table 1.

[0038] Table 1 Test Results Viscosity (mPa·s) Solid content (vol%) <![CDATA[Solidification density (g / cm 3 )]]> High temperature resistance performance (°C) Example 1 650 60 2.2 1000 Example 2 720 60 2.2 1000 Example 3 780 60 2.3 1000 Example 4 665 60 2.2 1000 Example 5 660 60 2.2 1000 Comparative Example 1 950 / / / Comparative Example 2 850 / / / Comparative Example 3 880 / / / Comparative Example 4 / / / 900 Comparative Example 5 750 / 1.7 / Comparative Example 6 1100 / 2.3 / Comparative Example 7 700 / / / As shown in Table 1, the viscosity of the low-viscosity and high-density water-based talcum casting slurries prepared in Examples 1 to 5 is 650-780 mPa·s, the solid content is 60 vol%, and the cured density is 2.2-2.3 g / cm 3 , and the high-temperature resistance can reach 1000 °C. The above results show that the low-viscosity and high-density water-based talcum casting slurry provided by the present invention has a small viscosity, excellent casting effect, and excellent high-temperature resistance of the prepared product, and can meet the use environment above 1000 °C.

[0039] In Comparative Example 1, no composite dispersant was used. It was found that the viscosity of the slurry prepared in Comparative Example 1 was 950 mPa·s, and the viscosity of the slurry in Comparative Example 1 was significantly higher than that in Example 1. This result indicates that the use of the composite dispersant can significantly reduce the viscosity of the talc slurry.

[0040] In Comparative Examples 2 and 3, polyacrylate and phosphate ester were used alone as dispersants. It was found that the viscosity of the slurry in Comparative Example 2 was 850 mPa·s, and the viscosity of the slurry in Comparative Example 3 was 880 mPa·s. Although the viscosities of the slurries in Comparative Examples 2 and 3 were lower than that in Comparative Example 1, they were still significantly higher than that in Example 1. This result indicates that although polyacrylate and phosphate ester can also significantly reduce the viscosity of the talc slurry when used alone as dispersants, the dispersant prepared by compounding polyacrylate and phosphate ester can further reduce the viscosity of the talc slurry, and the synergistic effect of polyacrylate and phosphate ester can extremely significantly reduce the viscosity of the talc slurry.

[0041] In Comparative Example 4, the talc powder was not acidified. It was found that the high-temperature resistance of Comparative Example 4 was only 900 °C, and the high-temperature resistance of Comparative Example 4 was significantly lower than that in Example 1. In addition, the talc powder without acidification treatment had poor dispersibility in water, and the uniformity of the formed material was extremely poor. This result indicates that the non-acidification treatment of the talc powder will result in low high-temperature resistance of the product after the talc slurry is cured, poor uniformity of the product, and low quality.

[0042] In Comparative Example 5, all coarse-grained talc powder was used. It was found that although the viscosity of the slurry made of coarse-grained talc powder was low, the density of the coarse-grained talc powder was low.

[0043] In Comparative Example 6, all fine-grained talc powder was used. It was found that the viscosity of the slurry made of fine-grained talc powder reached 1100 mPa·s, and the slurry casting performance was poor.

[0044] In Comparative Example 7, ultrasonic dispersion was not carried out. It was found that the viscosity of Comparative Example 7 was higher than that of Example 1. This result indicates that ultrasonic dispersion can also reduce the viscosity of the talc sizing material and increase the dispersibility of the talc slurry.

[0045] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent transformations made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A low-viscosity and high-density water-based talc casting slurry, characterized in that, The raw materials by mass parts include acidified talc powder, 1 - 2 parts of composite dispersant, 3 - 5 parts of water - based adhesive, and 25 - 35 parts of water. The composite dispersant is composed of polycarboxylate dispersant and phosphate ester dispersant.

2. The low-viscosity and high-density water-based talc casting slurry according to claim 1, characterized in that, The mass ratio of polycarboxylate dispersant to phosphate ester dispersant is 1.5 - 2:

1.

3. The low-viscosity high-density aqueous talc casting slurry according to claim 1 or 2, characterized in that, The polycarboxylate dispersant is sodium polyacrylate, and the phosphate ester dispersant is triethyl phosphate.

4. The low-viscosity high-density water-based talc casting slurry according to claim 1, characterized in that, The water - based adhesive is one or more of styrene - acrylic emulsion, styrene - butadiene emulsion, and acrylic emulsion; the raw materials also include a plasticizer, and the plasticizer is polyethylene glycol.

5. A method for preparing a low-viscosity and high-density aqueous talc casting slurry according to any one of claims 1 to 4, characterized in that, It includes the following steps: (1) Mix coarse - grained talc powder, medium - grained talc powder, and fine - grained talc powder and then conduct ball - milling treatment to make multi - level talc powder; (2) Immerse the multi - level talc powder in acid solution for acidification treatment to make acidified talc powder; (3) Ultrasonically disperse the acidified talc powder, composite dispersant, and deionized water to make a mixed solution, and then add the water - based adhesive and plasticizer to the mixed solution for stirring and vacuum defoaming to make a low - viscosity and high - density water - based talc casting slurry.

6. The preparation method according to claim 5, characterized in that, The mass ratio of coarse - grained talc powder, medium - grained talc powder, and fine - grained talc powder is 50 - 60:20 - 30:10 - 20.

7. The preparation method according to claim 5 or 6, characterized in that, The D50 of the coarse - grained talc powder is 14 - 16 μm, the D50 of the medium - grained talc powder is 6 - 7 μm, and the D50 of the fine - grained talc powder is 2 - 3 μm.

8. The preparation method according to claim 5, characterized in that, The acid solution is a 1 - 3 mol / L hydrochloric acid solution. The conditions of the acidification treatment include: temperature 60 - 80 °C, reaction time 2 - 4 h, rotation speed 400 - 500 rpm, and wash to neutral after acidification.

9. The preparation method according to claim 5, characterized in that, The conditions of the ultrasonic dispersion treatment include: ultrasonic frequency 30 - 50 kHz, ultrasonic power 750 - 850 w, and rotation speed 800 - 1000 rpm.

10. The preparation method according to claim 5, characterized in that, The vacuum degree of the vacuum defoaming treatment is - 0.01 - - 0.09 MPa.