A preparation method of a foamed gypsum lightweight board

Abstract

The present invention discloses a preparation method of a foamed gypsum lightweight board. Starch is used as the shell of the microcapsule, and the admixture is wrapped in the microcapsule. Then, the microcapsule and the gypsum powder are evenly distributed by using a mixer, and the uniform distribution of the gypsum powder and the admixture is achieved through the water absorption and expansion of the starch. 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 a porous foam regulation system with a filtering and separating function is combined to enhance the regulation and stability of the foam pore size, so that the prepared foamed gypsum lightweight board is rich in a large number of uniformly dispersed pores, and the stability of the foam pore size structure is achieved. The foamed gypsum lightweight board of the present invention has the advantages of high strength, low thermal conductivity, stable pore structure, small density and light weight, and can combine decoration and heat preservation, and can be widely applied to the heat preservation and decoration board of building walls.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly to a preparation method of a foamed gypsum lightweight board. Background Art

[0002] Foamed gypsum boards usually use physical foaming, that is, a foaming agent is pressurized and foamed into foam by a foaming machine, and then the foam is incorporated into the gypsum slurry and stirred evenly. The incorporated foam is evenly dispersed in the gypsum slurry to form a cavity foam structure, and a foamed gypsum material is obtained along with the gypsum gel. Most of the internal space of the foamed gypsum material is occupied by pores, so the density of the foamed gypsum is low, and the dispersed pores endow the foamed gypsum material with excellent light weight, heat insulation and sound insulation properties. It is often used in interior partition walls 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, various additives are usually added, such as water reducing agents, water retaining agents, setting retarders, defoaming agents and thickening agents, etc. However, most studies simply mix these additives with gypsum powder, which may lead to uneven mixing between the gypsum powder and the additives, thus affecting the effectiveness of the additives and ultimately resulting in unstable performance of the prepared foamed gypsum lightweight boards. In addition, the quality of the foaming effect has a great impact on the quality of the gypsum board. During the process of introducing foam into the gypsum mortar, physical foaming technology is difficult to effectively control the size of the foam pores, resulting in a random pore size structure, uneven foaming, poor foam stability, stratification and other phenomena, and the mechanical properties and light weight characteristics cannot be fully optimized. Therefore, it is necessary to explore a more efficient mixing method to ensure the uniform distribution of the additives and the gypsum powder and to achieve the stability of the foam pore size structure, so as to improve the overall performance of the foamed gypsum lightweight board. Summary of the Invention

[0004] Aiming at the above deficiencies of the prior art, the technical problem to be solved by the present invention is: how to provide a preparation method of a foamed gypsum lightweight board to solve the problems commonly existing in the existing preparation processes, such as uneven mixing of gypsum powder and additives, uneven foaming, poor foam stability, resulting in a random pore size structure and poor overall performance of the board.

[0005] To solve the above technical problems, the present invention adopts the following technical scheme: A preparation method of a foamed gypsum lightweight board, comprising the following steps:

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

[0007] S2: Place the admixture into the colloidal solution prepared in step S1, and perform ultrasonic treatment to evenly distribute the admixture. Then add a surfactant to improve the dispersibility of the core substance and avoid particle agglomeration. Stir evenly to obtain an emulsion; the admixture includes one or more of cellulose ether, naphthalene-based water reducer, and air-entraining agent.

[0008] S3: Cool the emulsion prepared in step S2 (such as in a water bath, ice bath, or freezing equipment). After forming a microcapsule structure with starch as the shell and the admixture as the core, take out the microcapsules and perform washing and drying treatments; among them, starch has excellent film-forming properties and can form a uniform microcapsule core-shell to protect the internal admixture components of the microcapsule and avoid direct contact between the admixture and gypsum powder, etc.

[0009] S4: Mix gypsum powder, sulfate cement, heavy calcium powder, and silica fume, then perform preliminary mixing by ball milling. After adding expanded perlite beads, place them in a cement mortar mixer and stir to obtain a uniform powder. In this way, the uniformity of the distribution of each component is ensured. At the same time, the ground gypsum powder has a larger specific surface area, which can more effectively contact and react with other materials, thereby improving the later hydration rate.

[0010] S5: Mix the microcapsules prepared in step S3 and the powder prepared in step S4 evenly, 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 containing the admixture mix evenly with powders such as gypsum powder. In addition, starch can absorb water and swell in water, and then the admixture in the microcapsule is gradually released into the slurry. This controlled-release characteristic enables the admixture to continuously play a role during the hydration process of the slurry and improve the properties 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 within 1.0 - 2.0 mm to obtain a uniform and stable foam. First, during the foaming process, a constant temperature control system is used to control the size of the bubbles, making them 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 foam stability. The newly foamed gypsum board with a foam temperature of about 20°C shows the highest stability level, making the prepared foamed gypsum lightweight board have a more uniform pore structure. Second, a 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, making the bubbles reach a consistent size. At the same time, the foam passes through a filter medium, and the liquid is separated out while the bubbles are retained. Selecting a filter medium with an appropriate pore size can ensure that the bubbles will not be squeezed or broken when passing through, thus maintaining their shape and size.

[0012] S7: Add the foam prepared in step S6 to the slurry prepared in step S5 in multiple batches, and use a stirrer to mix. After hydration setting and drying, the foamed gypsum lightweight board is obtained. In this way, the foamed foam is added to the uniformly mixed slurry in batches and quantitatively, and a stirrer with an appropriate rotation speed is used for mixing, 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; the mass ratio of the starch to water is 1:1.5 - 1:2.

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

[0015] Preferably, the surfactant in step S2 is sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, α-olefin sulfonate or polyoxyethylene lauryl ether, and the dosage of the surfactant is 0.5 wt% - 1.3 wt% of the admixture.

[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 - 74 parts of gypsum powder, 3 - 4 parts of sulfate cement, 1 - 1.5 parts of heavy calcium powder, 13 parts of silica fume, and 3.5 - 4 parts of vitrified microspheres; the ball milling time is 5 - 10 min; the mixer speed is 90 - 120 r / min, and the time is 90 - 120 s.

[0019] Preferably, the mass ratio of water to the powder in step S5 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, by controlling the operating pressure and the flow rate simultaneously, it effectively prevents the foam from breaking and being damaged during the filtration process, further optimizing the foaming effect. By adjusting the appropriate flow rate, the controlled release and uniform distribution of bubbles can be achieved.

[0021] Preferably, the rotational speed of the stirrer in step S7 is 100-150 rpm, and the stirring time is 60-90 s. In this way, 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 foamed gypsum lightweight board prepared by the above method.

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

[0024] 1. In the present invention, starch is used as the shell of the microcapsule to encapsulate the admixture in the microcapsule, and then the microcapsule and gypsum powder are evenly distributed by a mixer. Then, through the water absorption and swelling of starch, the uniform distribution of gypsum powder and admixture is realized, 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 filtering and separation method is combined to enhance the regulation of the stable foam pore size, so that the prepared foamed gypsum lightweight board is rich in a large number of uniformly dispersed pores, and the stability of the foam pore size structure is realized, reducing the thermal conductivity and apparent density of the material, and improving the lightweight and heat insulation performance of the material. The present invention solves the problems commonly existing in the existing preparation processes, such as uneven mixing of gypsum powder and admixture, and unstable foaming structure, 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%, the flexural strength is increased by 27-61%, the bubble size is uniform and dispersed, and it has the advantages of high strength, low thermal conductivity, stable structure, small density and light weight, and can combine decoration and heat insulation, and can be widely used in the thermal insulation and decoration board of building walls.

[0026] 3. The operation of the present invention is simple, without introducing toxic or environmentally polluting chemical substances, saving costs, being safe and environmentally friendly, with 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 of waste materials and the restoration of the ecological environment, and can achieve great social and economic benefits. Description of the Drawings

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

[0028] Figure 2 This is the pore size distribution diagram of the foamed gypsum lightweight board of the present invention. Detailed implementation manners

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

[0030] I. A preparation method of a foamed gypsum lightweight board

[0031] Embodiment 1 A preparation method of a foamed gypsum lightweight board, which adopts 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 500 r / min to form a uniform colloidal solution.

[0033] S2: Place the admixtures (0.45 part of cellulose ether, 0.45 part of naphthalene-based water reducer, and 0.035 part of air-entraining agent) into the colloidal solution prepared in step S1, and perform ultrasonic treatment. The ultrasonic power is 50 - 60 W, the frequency is 20 kHz, and the treatment time is 25 - 30 min to ensure the uniform distribution of the admixtures. Then add sodium dodecyl sulfate according to 0.5 wt% of the total mass of the admixtures and stir evenly to obtain an emulsion.

[0034] S3: Cool the emulsion prepared in step S2 under water bath conditions at a temperature of 15°C. After forming a microcapsule structure with starch as the shell and admixtures as the core, take out the microcapsules and perform washing and drying treatments.

[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 perform preliminary mixing by ball milling. After adding 4 parts of expanded perlite, place it in a cement mortar mixer and stir. The operating speed of the mixer is 90 - 120 r / min, and stir for 90 - 120 s to obtain a uniform powder material.

[0036] S5: Mix the microcapsules prepared in step S3 and the powder material prepared in step S4 evenly, then add water so that the mass ratio of water to the powder material is 0.62, continue to stir evenly, and the stirring speed is 90 - 120 r / min, and stir for 90 - 120 s to obtain a uniform slurry.

[0037] 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 20 °C. The pore size range of the porous foam control system is controlled within 1.0 - 2.0 mm, the operating pressure is within the range of 0.1 - 0.3 MPa, and the flow rate is controlled within the range of 0.1 - 1.5 L / min to obtain uniform and stable foam.

[0038] S7: Take 4.5 parts of the foam prepared in step S6 and add it to the slurry prepared in step S5 in three portions, and use a stirrer to mix them. The rotation speed is 100 - 150 rpm and the time is 60 - 90 s. After hydration condensation and drying, the foamed gypsum lightweight board is obtained.

[0039] Example 2 A method for preparing a foamed gypsum lightweight board, which adopts 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 500 r / min to form a uniform colloidal solution.

[0041] S2: Place the admixtures (0.45 parts of cellulose ether, 0.45 parts of naphthalene-based water reducer, and 0.035 parts of air-entraining agent) into the colloidal solution prepared in step S1, and perform ultrasonic treatment. The ultrasonic power is 50 - 60 W, the frequency is 20 kHz, and the treatment time is 25 - 30 min to ensure the uniform distribution of the admixtures. Then add sodium dodecyl sulfate according to 0.5 wt% of the total mass of the admixtures and stir evenly to obtain an emulsion.

[0042] S3: Cool the emulsion prepared in step S2 under water bath conditions at a temperature of 15 °C. After forming a microcapsule structure with starch as the shell and admixtures as the core, take out the microcapsules and perform washing and drying treatments.

[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 perform preliminary mixing by ball milling. After adding 3.5 parts of expanded perlite, place it in a cement mortar mixer and stir. The operating speed of the mixer is 90 - 120 r / min and stir for 90 - 120 s to obtain a uniform powder.

[0044] S5: Mix the microcapsules prepared in step S3 and the powder prepared in step S4 evenly, then add water so that the mass ratio of water to powder is 0.65, and continue to stir evenly. The operating speed of the mixer is 90 - 120 r / min and the operating time is 90 - 120 s to obtain a uniform slurry.

[0045] 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 20 °C. The pore size range of the porous foam control system is controlled within 1.0 - 2.0 mm, the operating pressure is within the range of 0.1 - 0.3 MPa, and the flow rate is controlled within the range of 0.1 - 1.5 L / min to obtain uniform and stable foam.

[0046] S7: Take 4 portions of the foam prepared in step S6 and add them to the slurry prepared in step S5 in three times, and use a stirrer to mix them. The rotation speed is 100 - 150 rpm and the time is 60 - 90 s. After hydration condensation and drying, the foamed gypsum lightweight board is obtained.

[0047] Example 3 A preparation method of a foamed gypsum lightweight board, comprising the following steps:

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

[0049] S2: Place the admixtures (0.45 portion of cellulose ether, 0.45 portion of naphthalene-based water reducer, and 0.04 portion of air-entraining agent) into the colloidal solution prepared in step S1, and perform ultrasonic treatment. The ultrasonic power is 50 - 60 W, the frequency is 20 kHz, and the treatment time is 25 - 30 min to ensure uniform distribution of the admixtures. Then add sodium dodecyl sulfate according to 0.5 wt% of the total mass of the admixtures and stir evenly to obtain an emulsion.

[0050] S3: Cool the emulsion prepared in step S2 under water bath conditions at a temperature of 15 °C. After forming a microcapsule structure with starch as the shell and admixtures as the core, take out the microcapsules and perform washing and drying treatments.

[0051] S4: Mix 73 portions of gypsum powder, 3 portions of sulfate cement, 1 portion of heavy calcium powder, and 13 portions of silica fume, then perform preliminary mixing by ball milling. After adding 3.5 portions of expanded perlite, place it in a cement mortar mixer and stir. The operating speed of the mixer is 90 - 120 r / min and stir for 90 - 120 s to obtain a uniform powder.

[0052] S5: Mix the microcapsules prepared in step S3 and the powder prepared in step S4 evenly, then add water so that the mass ratio of water to powder is 0.62, and continue to stir evenly. The operating speed of the mixer 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 foamer 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 1.0 - 2.0 mm, the operating pressure is within the range of 0.1 - 0.3 MPa, and the flow rate is controlled within the range of 0.1 - 1.5 L / min to obtain uniform and stable foam.

[0054] S7: Take 4 portions of the foam prepared in step S6 and add them to the slurry prepared in step S5 in three times, and use a stirrer to mix them. The rotation speed is 100 - 150 rpm and the time is 60 - 90 s. After hydration condensation and drying, the foamed gypsum lightweight board is obtained.

[0055] Example 4 A preparation method of a foamed gypsum lightweight board, comprising the following steps:

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

[0057] S2: Place the admixtures (0.45 portion of cellulose ether, 0.45 portion of naphthalene-based water reducer, and 0.035 portion of air-entraining agent) into the colloidal solution prepared in step S1, and perform ultrasonic treatment. The ultrasonic power is 50 - 60 W, the frequency is 20 kHz, and the treatment time is 25 - 30 min to ensure uniform distribution of the admixtures. Then add sodium dodecyl sulfate according to 0.5 wt% of the total mass of the admixtures and stir evenly to obtain an emulsion.

[0058] S3: Cool the emulsion prepared in step S2 under water bath conditions at a temperature of 15 °C. After forming a microcapsule structure with starch as the shell and admixtures as the core, take out the microcapsules and perform washing and drying treatments.

[0059] S4: Mix 73 portions of gypsum powder, 3 portions of sulfate cement, 1 portion of heavy calcium powder, and 13 portions of silica fume, then perform preliminary mixing by ball milling. After adding 3.5 portions of expanded perlite, place it in a cement mortar mixer and stir. The operating speed of the mixer is 90 - 120 r / min and stir for 90 - 120 s to obtain a uniform powder.

[0060] S5: Mix the microcapsules prepared in step S3 and the powder prepared in step S4 evenly, then add water so that the mass ratio of water to powder is 0.65, and continue to stir evenly. The operating speed of the mixer is 90 - 120 r / min and the operating time is 90 - 120 s to obtain a uniform slurry.

[0061] 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 20°C. The pore size range of the porous foam control system is controlled within 1.0 - 2.0 mm, the operating pressure is within the range of 0.1 - 0.3 MPa, and the flow rate is controlled within the range of 0.1 - 1.5 L / min to obtain uniform and stable foam.

[0062] S7: Take 4.5 parts of the foam prepared in step S6 and add it to the slurry prepared in step S5 in three portions, and use a stirrer to mix them. The rotation speed is 100 - 150 rpm, and the time is 60 - 90 s. After hydration condensation and drying, the foamed gypsum lightweight board is obtained.

[0063] Example 5 A method for preparing a foamed gypsum lightweight board, comprising 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 500 r / min to form a uniform colloidal solution.

[0065] S2: Place the admixtures (0.45 part of cellulose ether, 0.45 part of naphthalene-based water reducer, and 0.04 part of air-entraining agent) into the colloidal solution prepared in step S1, and perform ultrasonic treatment. The ultrasonic power is 50 - 60 W, the frequency is 20 kHz, and the treatment time is 25 - 30 min to ensure the uniform distribution of the admixtures. Then add sodium dodecyl sulfate according to 0.5 wt% of the total mass of the admixtures and stir evenly to obtain an emulsion.

[0066] S3: Cool the emulsion prepared in step S2 under water bath conditions at a temperature of 15°C. After forming a microcapsule structure with starch as the shell and the admixtures as the core, take out the microcapsules and perform washing and drying treatments.

[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 perform preliminary mixing by ball milling. After adding 3.5 parts of expanded perlite, place it in a cement mortar mixer and stir. The operating speed of the mixer is 90 - 120 r / min, and stir for 90 - 120 s to obtain a uniform powder.

[0068] S5: Mix the microcapsules prepared in step S3 and the powder prepared in step S4 evenly, then add water so that the mass ratio of water to the powder is 0.62, and continue to stir evenly. The stirring speed is 90 - 120 r / min, and stir for 90 - 120 s to obtain a uniform slurry.

[0069] 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 20 °C. The pore size range of the porous foam control system is controlled within 1.0 - 2.0 mm, the operating pressure is within the range of 0.1 - 0.3 MPa, and the flow rate is controlled within the range of 0.1 - 1.5 L / min to obtain uniform and stable foam.

[0070] S7: Take 4.5 parts of the foam prepared in step S6 and add it to the slurry prepared in step S5 in three portions, and use a stirrer to mix it at a rotation speed of 100 - 150 rpm for 60 - 90 s. After hydration setting and drying, the foamed gypsum lightweight board is obtained.

[0071] Example 6 A preparation method of a foamed gypsum lightweight board, comprising 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 500 r / min to form a uniform colloidal solution.

[0073] S2: Place the admixtures (0.45 part of cellulose ether, 0.45 part of naphthalene-based water reducer and 0.04 part of air-entraining agent) into the colloidal solution prepared in step S1, and perform ultrasonic treatment. The ultrasonic power is 50 - 60 W, the frequency is 20 kHz, and the treatment time is 25 - 30 min to ensure the uniform distribution of the admixtures. Then add sodium dodecyl sulfate according to 0.5 wt% of the total mass of the admixtures and stir evenly to obtain an emulsion.

[0074] S3: Cool the emulsion prepared in step S2 under water bath conditions at a temperature of 15 °C. After forming a microcapsule structure with starch as the shell and admixtures as the core, take out the microcapsules and perform washing and drying treatments.

[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, then perform preliminary mixing by ball milling. After adding 4 parts of expanded perlite beads, place it in a cement mortar mixer and stir at a mixer operating speed of 90 - 120 r / min for 90 - 120 s to obtain a uniform powder.

[0076] S5: Mix the microcapsules prepared in step S3 and the powder prepared in step S4 evenly, then add water so that the mass ratio of water to powder is 0.65, and continue to stir evenly at a stirring speed of 90 - 120 r / min for 90 - 120 s to obtain a uniform slurry.

[0077] 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 20 °C. The pore size range of the porous foam control system is controlled within 1.0 - 2.0 mm, the operating pressure is within the range of 0.1 - 0.3 MPa, and the flow rate is controlled within the range of 0.1 - 1.5 L / min to obtain uniform and stable foam.

[0078] S7: Take 4 portions of the foam prepared in step S6 and add them to the slurry prepared in step S5 in three times, and use a stirrer to mix them. The rotation speed is 100 - 150 rpm and the time is 60 - 90 s. After hydration condensation and drying, the foamed gypsum lightweight board is obtained.

[0079] Comparative Example 1

[0080] The admixture was not microencapsulated and was directly mixed with the surfactant and the powder. Other steps were the same as in Example 1.

[0081] Comparative Example 2

[0082] Foaming was carried out using a conventional foamer without constant temperature control and filtration treatment. Other steps were the same as in Example 1.

[0083] II. 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. Then, Nanomeasurer was used to count the pore size of its pores, and the results are as Figure 2 shown.

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

[0086] 2. Using conventional methods, the water absorption rate, absolute dry apparent density, softening coefficient, thermal conductivity, compressive strength, and flexural strength of the foamed gypsum lightweight boards prepared in Examples 1 - 6 and Comparative Examples 1 - 2 were detected respectively, and 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, with a compressive strength of 5.2 - 6.2 MPa, a flexural strength of 2.3 - 3.4 MPa, a thermal conductivity between 0.145 W( / m·k) and 0.162 W( / m·k), a softening coefficient that can reach 0.52, and an absolute dry apparent density of 497 - 554 kg / m 3 , significantly improving the sound insulation and heat insulation performance, and can be widely used as a thermal insulation decorative board for building walls. 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%, showing significant advantages.

[0090] The above are only the preferred embodiments of the present invention, and the present invention is not limited thereto. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall 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; 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; 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 1:1.5-1:

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%-1.3wt% of the admixture.

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: 73-74 parts of gypsum powder, 3-4 parts of sulfate cement, 1-1.5 parts of heavy calcium powder, 13 parts of silica fume and 3.5-4 parts of vitrified microspheres; the ball milling time is 5-10 minutes; the speed of the mixer is 90-120 r / min, and the time is 90-120 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.

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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