Preparation method of foamed gypsum lightweight board

Abstract

The invention discloses a preparation method of a foamed gypsum lightweight board, which comprises the following steps: taking starch as a shell of a microcapsule, wrapping an admixture in the microcapsule, then uniformly distributing the microcapsule and gypsum powder by using a stirrer, and then realizing uniform distribution of the gypsum powder and the admixture through water absorption expansion of the starch. And on the other hand, based on constant-temperature treatment of the foaming agent solution, optimization of the uniformity and stability of the foam, and combination of a porous foam regulation and control system with filtration and separation effects, regulation and control are enhanced, and the foam pore diameter is stabilized, so that the prepared foamed gypsum lightweight board is rich in a large number of uniformly dispersed foam pores, and the stability of the foam pore diameter structure is realized. The foamed gypsum lightweight board has the advantages of high strength, low thermal conductivity, stable pore structure, small density, light weight and the like, can integrate decoration and heat preservation, and can be widely applied to heat preservation decorative boards of building walls.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a method for preparing a foamed gypsum lightweight board. Background Art

[0002] Foamed gypsum board usually adopts physical foaming, that is, using a foaming machine to pressurize the foaming agent into foam, and then the foam is mixed into the gypsum slurry and stirred evenly. The added foam is evenly dispersed in the gypsum slurry after stirring to form a cavity bubble structure, and the foamed gypsum material is obtained with the gypsum gel. Most of the space inside the foamed gypsum material is occupied by pores, so the density of the foamed gypsum is low, and the dispersed pores make the foamed gypsum material have excellent light weight, thermal insulation and sound insulation properties. It is often used in indoor partitions and ceilings, exterior wall insulation systems and special places (such as theaters, concert halls, etc.).

[0003] When preparing foamed gypsum lightweight boards, in order to meet the required physical properties, a variety of admixtures are usually added, such as water reducers, water retainers, retarders, defoamers and thickeners. However, most studies simply mix these admixtures with gypsum powder, which may lead to uneven mixing between gypsum powder and admixtures, thereby affecting the effectiveness of the admixtures and ultimately leading to unstable performance of the prepared foamed gypsum lightweight boards. In addition, the quality of the foaming effect has a great influence on the quality of the gypsum board. In the process of introducing foam into the gypsum mortar, the physical foaming technology is difficult to effectively control the size of the foam pore size, resulting in a random pore structure, uneven foaming, poor foam stability, stratification and other phenomena, and it is impossible to fully optimize the mechanical properties and lightweight characteristics. Therefore, it is necessary to explore a more efficient mixing method to ensure the uniform distribution of admixtures and gypsum powder and achieve the stability of the foam pore structure, so as to improve the overall performance of the foamed gypsum lightweight board. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a method for preparing a foamed gypsum lightweight board to solve the problems commonly existing in the existing preparation process, such as uneven mixing of gypsum powder and admixtures, uneven foaming, poor foam stability, resulting in random pore structure, and poor overall performance of the board.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for preparing a foamed gypsum lightweight board, comprising the following steps:

[0006] S1: Add starch into water and heat and stir to form a uniform colloidal solution.

[0007] S2: placing an admixture in the colloidal solution prepared in step S1, subjecting the solution to ultrasonic treatment to uniformly distribute the admixture, then adding a surfactant to improve the dispersibility of the core material and avoid particle agglomeration, and stirring the solution to uniformly obtain an emulsion; the admixture comprises one or more of cellulose ether, naphthalene-based water reducer and air entraining agent.

[0008] S3: Cooling the emulsion prepared in step S2 (such as in a water bath, an ice bath or a freezing device), and after a microcapsule structure with starch as a shell and an additive as a core is formed, taking out the microcapsules, washing them and drying them; wherein starch has excellent film-forming properties, and can form a uniform microcapsule core-shell, protecting the additive components inside the microcapsules, and avoiding direct contact between the additives and gypsum powder, etc.

[0009] S4: Gypsum powder, sulfate cement, heavy calcium powder and silica fume are mixed, and then preliminarily mixed by ball milling. After adding vitrified microspheres, the mixture is placed in a cement mortar mixer and stirred to obtain a uniform powder. In this way, the uniformity of the distribution of each component is ensured, and the ground gypsum powder has a larger specific surface area, which can more effectively contact and react with other materials, thereby increasing the hydration rate in the later stage.

[0010] S5: Evenly mix the microcapsules prepared in step S3 with the powder prepared in step S4, then add water and continue to stir evenly to obtain a uniform slurry. In this way, on the one hand, the presence of the microcapsules can make the microcapsules encapsulating the admixtures evenly mixed with the powders such as gypsum powder. In addition, starch can absorb water and swell in water, thereby gradually releasing the admixture in the microcapsules into the slurry. This controlled release property allows the admixture to continue to play a role in the hydration process of the slurry and improve the performance of gypsum.

[0011] S6: Pour the foaming agent into a foamer equipped with a constant temperature control device and a porous foam control system for foaming. The foaming temperature is 15-25°C, and the pore size range of the porous foam control system is controlled at 1.0-2.0 mm to obtain uniform and stable foam. First, the constant temperature control system is used to control the size of the bubbles during the foaming process, so that they are evenly distributed within a certain range. Adjusting the appropriate temperature can reduce the surface tension of the surfactant, reduce the diameter of the bubbles, and delay the coarsening of the bubbles, thereby enhancing the stability of the foam. The new foamed gypsum board with a foam temperature of about 20°C shows the highest stability level, so that the prepared foamed gypsum lightweight board has a more uniform pore structure. Secondly, the polypropylene porous foam control system is used to control the pore size range of the foamer, effectively controlling the uniformity of the foam pore size, so that the bubbles reach a consistent size. At the same time, the foam passes through the filter medium, the liquid is separated, and the bubbles are retained. The selection of a filter medium with an appropriate pore size can ensure that the bubbles will not be squeezed or broken when passing through, thereby maintaining their shape and size.

[0012] S7: adding the foam obtained in step S6 to the slurry prepared in step S5 in batches, mixing with a stirrer, hydrating, condensing and drying to obtain the foamed gypsum lightweight board. In this way, the foamed foam is added to the uniformly mixed slurry in batches and quantitatively, and mixed with a stirrer at an appropriate speed, ensuring the uniform combination of the foam and the slurry, and improving the overall performance of the foamed gypsum lightweight board.

[0013] Preferably, the starch in step S1 is corn starch or potato starch; and the mass ratio of the starch to water is 1:1.5 to 1:2.

[0014] Preferably, in step S1, the heating temperature is 80-90° C. and the stirring speed is 450-500 r / min.

[0015] Preferably, the surfactant in step S2 is sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate or dodecyl polyoxyethylene ether, and the amount of the surfactant used is 0.5wt% to 1.3wt% of the additive.

[0016] Preferably, during the ultrasonic treatment in step S2, the ultrasonic power is 50-60 W, the frequency is 20 kHz, and the treatment time is 25-30 min.

[0017] Preferably, the cooling temperature in step S3 is 4-15°C.

[0018] Preferably, the powder in step S4 includes the following raw materials in parts by weight: 73 to 74 parts of gypsum powder, 3 to 4 parts of sulfate cement, 1 to 1.5 parts of heavy calcium powder, 13 parts of silica fume and 3.5 to 4 parts of vitrified microspheres; the ball milling time is 5 to 10 minutes; the mixer speed is 90 to 120 r / min, and the time is 90 to 120 seconds.

[0019] Preferably, in step S5, the mass ratio of water to powder is 0.62-0.65:1, the stirring speed is 90-120 r / min, and the running time is 90-120 s.

[0020] Preferably, the foaming agent in step S6 is one or more of sodium bicarbonate, sodium peroxide and foam glass powder; the operating pressure of the porous foam control system is 0.1-0.3 MPa, and the flow rate is 0.1-1.5 L / min. In this way, the operating pressure and flow rate are controlled at the same time, which effectively prevents the foam from breaking and being damaged during the filtration process, and further optimizes the foaming effect. By adjusting the appropriate flow rate, the controlled release and uniform distribution of bubbles can be achieved.

[0021] Preferably, the speed of the stirrer in step S7 is 100-150 rpm, and the stirring time is 60-90 seconds. Thus, by adjusting the stirring time and speed during foaming, the uniform size of the bubbles can be further optimized.

[0022] Another object of the present invention is to provide a lightweight foamed gypsum board prepared by the above method.

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

[0024] 1. The present invention uses starch as the shell of microcapsules, wraps the admixture in the microcapsules, and then uses a mixer to evenly distribute the microcapsules and gypsum powder. The water absorption and expansion of starch achieves even distribution of gypsum powder and admixtures, thereby improving the mechanical properties, durability, and crack resistance of the foamed gypsum lightweight board. On the other hand, based on the constant temperature treatment of the foaming agent solution, the uniformity and stability of the foam are optimized, and the filtration separation method is combined to enhance the regulation and control of the stable foam pore size, so that the prepared foamed gypsum lightweight board is rich in a large number of evenly dispersed pores, and the stability of the foam pore size structure is achieved, the thermal conductivity and apparent density of the material are reduced, and the lightweight thermal insulation performance of the material is improved. The present invention solves the problems of uneven mixing of gypsum powder and admixtures and unstable foaming structure that are common in existing preparation processes, and comprehensively improves the performance of the foamed gypsum lightweight board.

[0025] 2. The compressive strength of the foamed gypsum lightweight board prepared by the present invention is 5.2-6.2 MPa, the flexural strength is 2.3-3.4 MPa, the thermal conductivity is between 0.145 W ( / m·k) and 0.162 W ( / m·k), the softening coefficient can reach 0.52, and the absolute dry apparent density is 497-554 kg / m 3 , significantly improving the sound insulation and heat insulation performance. Compared with the comparative example, the compressive strength of the foamed gypsum lightweight board of the present invention is increased by 17-40%, and the flexural strength is increased by 27-61%. The pore size is uniform and dispersed, and it has the advantages of high strength, low thermal conductivity, stable structure, low density and light weight. It can integrate decorative and thermal insulation properties and can be widely used as thermal insulation decorative panels for building walls.

[0026] 3. The present invention is easy to operate, does not introduce toxic or environmentally polluting chemicals, is cost-saving, safe and environmentally friendly, has a simple process and a short production cycle. In addition, the foamed gypsum lightweight board uses industrial solid wastes such as phosphogypsum and silica fume as raw materials, which can not only significantly reduce production costs and energy consumption, but also provide technical support for the recycling and reuse of waste materials and ecological environment restoration, and can achieve huge social and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1It is a cross-sectional view of the foamed gypsum lightweight board of the present invention.

[0028] Figure 2 This is a pore size distribution diagram of the foamed gypsum lightweight board of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the examples. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources. The parts in the following examples are by weight unless otherwise specified.

[0030] 1. A method for preparing a lightweight foamed gypsum board

[0031] Embodiment 1 A method for preparing a foamed gypsum lightweight board is provided, comprising the following steps:

[0032] S1: Take 3 parts of corn starch and add it to 6 parts of water, heat and stir to fully dissolve or disperse the starch. The heating temperature is 85°C and the stirring speed is 500r / min to form a uniform colloidal solution.

[0033] S2: Adding an admixture (0.45 parts of cellulose ether, 0.45 parts of naphthalene-based water-reducing agent and 0.035 parts of air-entraining agent) to the colloidal solution prepared in step S1, and subjecting the solution to ultrasonic treatment, wherein the ultrasonic power is 50 to 60 W, the frequency is 20 kHz, and the treatment time is 25 to 30 min to ensure that the admixture is evenly distributed, and then adding sodium lauryl sulfate according to 0.5 wt % of the total mass of the admixture, and stirring to obtain an emulsion.

[0034] S3: The emulsion prepared in step S2 is cooled in a water bath at a temperature of 15° C. After a microcapsule structure with starch as a shell and an additive as a core is formed, the microcapsules are taken out and washed and dried.

[0035] S4: Mix 74 parts of gypsum powder, 4 parts of sulfate cement, 1.5 parts of heavy calcium powder and 13 parts of silica fume, and then use a ball mill for preliminary mixing. After adding 4 parts of vitrified microspheres, place it in a cement mortar mixer and stir it at a speed of 90 to 120 r / min for 90 to 120 seconds to obtain a uniform powder.

[0036] S5: The microcapsules prepared in step S3 and the powder prepared in step S4 are uniformly mixed, and then water is added to make the mass ratio of water to powder be 0.62, and stirring is continued at a speed of 90 to 120 r / min for 90 to 120 s to obtain a uniform slurry.

[0037] S6: Pour the foaming agent into a foaming machine equipped with a constant temperature control device and a porous foam control system for foaming, the foaming temperature is 20°C, the pore size range of the porous foam control system is controlled within the range of 1.0 to 2.0 mm, the operating pressure is within the range of 0.1 to 0.3 MPa, and the flow rate is controlled within the range of 0.1 to 1.5 L / min to obtain a uniform and stable foam.

[0038] S7: Take 4.5 parts of the foam obtained in step S6 and add them into the slurry prepared in step S5 in three times, use a stirrer to mix at a speed of 100-150 rpm for 60-90 seconds, and obtain the foamed gypsum lightweight board through hydration, coagulation and drying.

[0039] Embodiment 2 A method for preparing a foamed gypsum lightweight board is carried out by the following steps:

[0040] S1: Take 3 parts of corn starch and add it to 6 parts of water, heat and stir to fully dissolve or disperse the starch. The heating temperature is 85°C and the stirring speed is 500r / min to form a uniform colloidal solution.

[0041] S2: Adding an admixture (0.45 parts of cellulose ether, 0.45 parts of naphthalene-based water-reducing agent and 0.035 parts of air-entraining agent) to the colloidal solution prepared in step S1, and subjecting the solution to ultrasonic treatment, wherein the ultrasonic power is 50-60 W, the frequency is 20 kHz, and the treatment time is 25-30 min to ensure that the admixture is evenly distributed, and then adding sodium lauryl sulfate according to 0.5 wt % of the total mass of the admixture, and stirring evenly to obtain an emulsion.

[0042] S3: The emulsion prepared in step S2 is cooled in a water bath at a temperature of 15° C. After a microcapsule structure with starch as a shell and an additive as a core is formed, the microcapsules are taken out and washed and dried.

[0043] S4: Mix 73 parts of gypsum powder, 3 parts of sulfate cement, 1 part of heavy calcium powder and 13 parts of silica fume, and then use a ball mill for preliminary mixing. After adding 3.5 parts of vitrified microspheres, place it in a cement mortar mixer and stir it at a speed of 90 to 120 r / min for 90 to 120 seconds to obtain a uniform powder.

[0044] S5: The microcapsules prepared in step S3 and the powder prepared in step S4 are uniformly mixed, and then water is added to make the mass ratio of water to powder be 0.65, and stirring is continued at a speed of 90 to 120 r / min for 90 to 120 s to obtain a uniform slurry.

[0045] S6: Pour the foaming agent into a foaming machine equipped with a constant temperature control device and a porous foam control system for foaming. The foaming temperature is 20°C, the pore size range of the porous foam control system is controlled within the range of 1.0 to 2.0 mm, the operating pressure is within the range of 0.1 to 0.3 MPa, and the flow rate is controlled within the range of 0.1 to 1.5 L / min to obtain uniform and stable foam.

[0046] S7: Take 4 portions of the foam obtained in step S6 and add them into the slurry prepared in step S5 in three times, and mix them with an agitator at a speed of 100 to 150 rpm for 60 to 90 seconds. After hydration, coagulation and drying, the foamed gypsum lightweight board is obtained.

[0047] Embodiment 3 A method for preparing a foamed gypsum lightweight board is carried out by the following steps:

[0048] S1: Take 3 parts of corn starch and add it to 6 parts of water, heat and stir to fully dissolve or disperse the starch. The heating temperature is 85°C and the stirring speed is 500r / min to form a uniform colloidal solution.

[0049] S2: Adding an admixture (0.45 parts of cellulose ether, 0.45 parts of naphthalene-based water-reducing agent and 0.04 parts of air-entraining agent) to the colloidal solution prepared in step S1, and subjecting the solution to ultrasonic treatment, wherein the ultrasonic power is 50-60 W, the frequency is 20 kHz, and the treatment time is 25-30 min to ensure that the admixture is evenly distributed, and then adding sodium lauryl sulfate according to 0.5 wt % of the total mass of the admixture, and stirring evenly to obtain an emulsion.

[0050] S3: The emulsion prepared in step S2 is cooled in a water bath at a temperature of 15° C. After a microcapsule structure with starch as a shell and an additive as a core is formed, the microcapsules are taken out and washed and dried.

[0051] S4: Mix 73 parts of gypsum powder, 3 parts of sulfate cement, 1 part of heavy calcium powder and 13 parts of silica fume, and then use a ball mill for preliminary mixing. After adding 3.5 parts of vitrified microspheres, place it in a cement mortar mixer and stir it at a speed of 90 to 120 r / min for 90 to 120 seconds to obtain a uniform powder.

[0052] S5: The microcapsules prepared in step S3 and the powder prepared in step S4 are uniformly mixed, and then water is added to make the mass ratio of water to powder be 0.62, and stirring is continued to be uniform, the operating speed of the stirrer is 90-120 r / min, and the operating time is 90-120 s to obtain a uniform slurry.

[0053] S6: Pour the foaming agent into a foaming machine equipped with a constant temperature control device and a porous foam control system for foaming. The foaming temperature is 20°C, the pore size range of the porous foam control system is controlled within the range of 1.0 to 2.0 mm, the operating pressure is within the range of 0.1 to 0.3 MPa, and the flow rate is controlled within the range of 0.1 to 1.5 L / min to obtain uniform and stable foam.

[0054] S7: Take 4 portions of the foam obtained in step S6 and add them into the slurry prepared in step S5 in three times, and mix them with an agitator at a speed of 100 to 150 rpm for 60 to 90 seconds. After hydration, coagulation and drying, the foamed gypsum lightweight board is obtained.

[0055] Embodiment 4 A method for preparing a foamed gypsum lightweight board is carried out by the following steps:

[0056] S1: Take 3 parts of corn starch and add it to 6 parts of water, heat and stir to fully dissolve or disperse the starch. The heating temperature is 85°C and the stirring speed is 500r / min to form a uniform colloidal solution.

[0057] S2: Adding an admixture (0.45 parts of cellulose ether, 0.45 parts of naphthalene-based water-reducing agent and 0.035 parts of air-entraining agent) to the colloidal solution prepared in step S1, and subjecting the solution to ultrasonic treatment, wherein the ultrasonic power is 50-60 W, the frequency is 20 kHz, and the treatment time is 25-30 min to ensure that the admixture is evenly distributed, and then adding sodium lauryl sulfate according to 0.5 wt % of the total mass of the admixture, and stirring evenly to obtain an emulsion.

[0058] S3: The emulsion prepared in step S2 is cooled in a water bath at a temperature of 15° C. After a microcapsule structure with starch as a shell and an additive as a core is formed, the microcapsules are taken out and washed and dried.

[0059] S4: Mix 73 parts of gypsum powder, 3 parts of sulfate cement, 1 part of heavy calcium powder and 13 parts of silica fume, and then use a ball mill for preliminary mixing. After adding 3.5 parts of vitrified microspheres, place it in a cement mortar mixer and stir it at a speed of 90 to 120 r / min for 90 to 120 seconds to obtain a uniform powder.

[0060] S5: The microcapsules prepared in step S3 and the powder prepared in step S4 are uniformly mixed, and then water is added to make the mass ratio of water to powder be 0.65, and stirring is continued at a speed of 90 to 120 r / min for 90 to 120 s to obtain a uniform slurry.

[0061] S6: Pour the foaming agent into a foaming machine equipped with a constant temperature control device and a porous foam control system for foaming. The foaming temperature is 20°C, the pore size range of the porous foam control system is controlled within the range of 1.0 to 2.0 mm, the operating pressure is within the range of 0.1 to 0.3 MPa, and the flow rate is controlled within the range of 0.1 to 1.5 L / min to obtain uniform and stable foam.

[0062] S7: Take 4.5 parts of the foam obtained in step S6 and add them into the slurry prepared in step S5 in three times, use a stirrer to mix at a speed of 100-150 rpm for 60-90 seconds, and obtain the foamed gypsum lightweight board through hydration, coagulation and drying.

[0063] Embodiment 5 A method for preparing a foamed gypsum lightweight board is carried out by the following steps:

[0064] S1: Take 3 parts of corn starch and add it to 6 parts of water, heat and stir to fully dissolve or disperse the starch. The heating temperature is 85°C and the stirring speed is 500r / min to form a uniform colloidal solution.

[0065] S2: Adding an admixture (0.45 parts of cellulose ether, 0.45 parts of naphthalene-based water-reducing agent and 0.04 parts of air-entraining agent) to the colloidal solution prepared in step S1, and subjecting the solution to ultrasonic treatment, wherein the ultrasonic power is 50-60 W, the frequency is 20 kHz, and the treatment time is 25-30 min to ensure that the admixture is evenly distributed, and then adding sodium lauryl sulfate according to 0.5 wt % of the total mass of the admixture, and stirring evenly to obtain an emulsion.

[0066] S3: The emulsion prepared in step S2 is cooled in a water bath at a temperature of 15° C. After a microcapsule structure with starch as a shell and an additive as a core is formed, the microcapsules are taken out and washed and dried.

[0067] S4: Mix 73 parts of gypsum powder, 3 parts of sulfate cement, 1 part of heavy calcium powder and 13 parts of silica fume, and then use a ball mill for preliminary mixing. After adding 3.5 parts of vitrified microspheres, place it in a cement mortar mixer and stir it at a speed of 90 to 120 r / min for 90 to 120 seconds to obtain a uniform powder.

[0068] S5: The microcapsules prepared in step S3 and the powder prepared in step S4 are uniformly mixed, and then water is added to make the mass ratio of water to powder be 0.62, and stirring is continued at a speed of 90 to 120 r / min for 90 to 120 s to obtain a uniform slurry.

[0069] S6: Pour the foaming agent into a foaming machine equipped with a constant temperature control device and a porous foam control system for foaming. The foaming temperature is 20°C, the pore size range of the porous foam control system is controlled within the range of 1.0 to 2.0 mm, the operating pressure is within the range of 0.1 to 0.3 MPa, and the flow rate is controlled within the range of 0.1 to 1.5 L / min to obtain uniform and stable foam.

[0070] S7: Take 4.5 parts of the foam obtained in step S6 and add them into the slurry prepared in step S5 in three times, use a stirrer to mix at a speed of 100-150 rpm for 60-90 seconds, and obtain the foamed gypsum lightweight board through hydration, coagulation and drying.

[0071] Embodiment 6 A method for preparing a foamed gypsum lightweight board is carried out by the following steps:

[0072] S1: Take 3 parts of corn starch and add it to 6 parts of water, heat and stir to fully dissolve or disperse the starch. The heating temperature is 85°C and the stirring speed is 500r / min to form a uniform colloidal solution.

[0073] S2: Adding an admixture (0.45 parts of cellulose ether, 0.45 parts of naphthalene-based water-reducing agent and 0.04 parts of air-entraining agent) to the colloidal solution prepared in step S1, and subjecting the solution to ultrasonic treatment, wherein the ultrasonic power is 50 to 60 W, the frequency is 20 kHz, and the treatment time is 25 to 30 min to ensure that the admixture is evenly distributed, and then adding sodium lauryl sulfate according to 0.5 wt % of the total mass of the admixture, and stirring evenly to obtain an emulsion.

[0074] S3: The emulsion prepared in step S2 is cooled in a water bath at a temperature of 15° C. After a microcapsule structure with starch as a shell and an additive as a core is formed, the microcapsules are taken out and washed and dried.

[0075] S4: Mix 74 parts of gypsum powder, 4 parts of sulfate cement, 1.5 parts of heavy calcium powder and 13 parts of silica fume, and then use a ball mill for preliminary mixing. After adding 4 parts of vitrified microspheres, place it in a cement mortar mixer and stir it at a speed of 90 to 120 r / min for 90 to 120 seconds to obtain a uniform powder.

[0076] S5: The microcapsules prepared in step S3 and the powder prepared in step S4 are uniformly mixed, and then water is added to make the mass ratio of water to powder be 0.65, and stirring is continued at a speed of 90 to 120 r / min for 90 to 120 s to obtain a uniform slurry.

[0077] S6: Pour the foaming agent into a foaming machine equipped with a constant temperature control device and a porous foam control system for foaming, the foaming temperature is 20°C, the pore size range of the porous foam control system is controlled within the range of 1.0 to 2.0 mm, the operating pressure is within the range of 0.1 to 0.3 MPa, and the flow rate is controlled within the range of 0.1 to 1.5 L / min to obtain a uniform and stable foam.

[0078] S7: Take 4 portions of the foam obtained in step S6 and add them into the slurry prepared in step S5 in three times, and mix them with an agitator at a speed of 100 to 150 rpm for 60 to 90 seconds. After hydration, coagulation and drying, the foamed gypsum lightweight board is obtained.

[0079] Comparative Example 1

[0080] The admixture was not subjected to microencapsulation treatment and was directly mixed with the surfactant and the powder. The other steps were the same as those in Example 1.

[0081] Comparative Example 2

[0082] The foaming was performed using a conventional foamer without constant temperature control and filtering. The other steps were the same as in Example 1.

[0083] 2. Performance Verification

[0084] 1. Figure 1 This is a cross-sectional view of the foamed gypsum lightweight board prepared in Example 1 of the present invention, and then the pore sizes thereof are counted using Nanomeasurer. The results are as follows Figure 2 shown.

[0085] from Figure 2 It can be seen that the pore size of the foamed gypsum lightweight board of the present invention is consistent, basically distributed in the range of 0.19 to 1 μm, and its average pore size is 0.77±0.46 μm. The foamed gypsum lightweight board is rich in a large number of evenly dispersed pores, and the surface is basically flat and the structure is stable ( Figure 1 ) to ensure that the foamed gypsum lightweight board has sufficient strength and flexural resistance.

[0086] 2. The water absorption, absolute dry apparent density, softening coefficient, thermal conductivity, compressive strength and flexural strength of the foamed gypsum lightweight boards prepared in Examples 1 to 6 and Comparative Examples 1 to 2 were tested by conventional methods. The results are shown in Table 1.

[0087] Table 1

[0088]

[0089] As can be seen from Table 1, the foamed gypsum lightweight board prepared by the present invention has been tested many times, and the compressive strength is 5.2-6.2 MPa, the flexural strength is 2.3-3.4 MPa, the thermal conductivity is between 0.145 W ( / m·k) and 0.162 W ( / m·k), the softening coefficient can reach 0.52, and the absolute dry apparent density is 497-554 kg / m 3 The sound insulation and heat insulation performance are significantly improved, and the insulation decorative board of the building wall can be widely used. Compared with the comparative example, the compressive strength of the foamed gypsum lightweight board of the present invention is increased by 17-40%, and the flexural strength is increased by 27-61%, which has significant advantages.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a lightweight foamed gypsum board, characterized in that: The following steps are involved: S1: Add starch into water and heat and stir to form a uniform colloidal solution; S2: placing an admixture in the colloidal solution prepared in step S1, subjecting the solution to ultrasonic treatment, and then adding a surfactant and stirring the mixture to obtain an emulsion; the admixture comprises one or more of cellulose ether, naphthalene-based water reducer and air entraining agent; S3: cooling the emulsion prepared in step S2, and after a microcapsule structure with starch as a shell and an additive as a core is formed, taking out the microcapsule, washing it, and drying it; S4: Gypsum powder, sulfate cement, heavy calcium powder and silica fume are mixed, and then preliminarily mixed by ball milling, and then vitrified microspheres are added and stirred in a mixer to obtain a uniform powder; S5: mixing the microcapsules prepared in step S3 and the powder prepared in step S4 uniformly, then adding water, and continuing to stir uniformly to obtain a uniform slurry; S6: pouring the foaming agent into a foaming device equipped with a constant temperature control device and a porous foam control system for foaming, the foaming temperature is 15-25° C., the pore size range of the porous foam control system is controlled to be 1.0-2.0 mm, and a uniform and stable foam is obtained; S7: adding the foam obtained in step S6 to the slurry prepared in step S5 in multiple times, mixing with a stirrer, hydrating, condensing and drying to obtain the foamed gypsum lightweight board.

2. The method for preparing the foamed gypsum lightweight board according to claim 1, characterized in that: The starch in step S1 is corn starch or potato starch; the mass ratio of the starch to water is 1:1.5 to 1:

2.

3. The method for preparing the foamed gypsum lightweight board according to claim 1, characterized in that: In step S1, the heating temperature is 80-90° C. and the stirring speed is 450-500 r / min.

4. The method for preparing the foamed gypsum lightweight board according to claim 1, characterized in that: In the ultrasonic treatment process in step S2, the ultrasonic power is 50-60W, the frequency is 20kHz, and the treatment time is 25-30min; the surfactant is sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate or dodecyl polyoxyethylene ether, and the amount of the surfactant is 0.5wt% to 1.3wt% of the additive.

5. The method for preparing the foamed gypsum lightweight board according to claim 1, characterized in that: The cooling temperature in step S3 is 4-15°C.

6. The method for preparing the foamed gypsum lightweight board according to claim 1, characterized in that: The powder in step S4 includes the following raw materials in parts by weight: 73 to 74 parts of gypsum powder, 3 to 4 parts of sulfate cement, 1 to 1.5 parts of heavy calcium powder, 13 parts of silica fume and 3.5 to 4 parts of vitrified microspheres; the ball milling time is 5 to 10 minutes; the speed of the mixer is 90 to 120 r / min, and the time is 90 to 120 seconds.

7. The method for preparing the foamed gypsum lightweight board according to claim 1, characterized in that: In step S5, the mass ratio of water to powder is 0.62-0.65:1, the stirring speed is 90-120 r / min, and the stirring time is 90-120 s.

8. The method for preparing the foamed gypsum lightweight board according to claim 1, characterized in that: The foaming agent in step S6 is one or more of sodium bicarbonate, sodium peroxide and foam glass powder; the operating pressure of the porous foam control system is 0.1-0.3 MPa, and the flow rate is 0.1-1.5 L / min.

9. The method for preparing the foamed gypsum lightweight board according to claim 1, characterized in that: In step S7, the rotation speed of the stirrer is 100-150 rpm, and the stirring time is 60-90 s.

10. A lightweight foamed gypsum board prepared according to the method according to any one of claims 1 to 9.

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