Preparation method and process of environment-friendly composite rubber powder for toughening gypsum

Abstract

The invention discloses a preparation method and process of environment-friendly composite rubber powder for toughening gypsum. The composite rubber powder is prepared by three steps. The preparation method comprises the following steps: 1, preparing 0.5-1.5 kg of lauryl sodium sulfate, 0.5-1.5 kg of dodecylphenol polyoxyethylene ether, 1.5-5 kg of hydroxypropyl methyl cellulose, 4.5-5 kg of vinyl acetate, 4.5-5 kg of vinyl versatate and 85-90 kg of deionized water, adding into a reaction kettle, and heating to prepare a seed emulsion; the preparation method comprises the following steps: 1, preparing a seed emulsion, adding vinyl acetate, vinyl versatate and potassium persulfate into the prepared seed emulsion according to a mass ratio of (65-85) kg: (65-85) kg: (1.5-3) kg to obtain an emulsion synthesized copolymer emulsion, 2, compounding the copolymer emulsion to form a mixed emulsion, and 3, carrying out spray drying to form the rubber powder. The composite rubber powder is prepared by controlling the reaction temperature, the stirring speed and different feeding ratios, a water-based reaction system is adopted in the rubber powder production process, the rubber powder is environmentally friendly, after a gypsum material is added, the toughness of the gypsum material can be effectively improved, cracking of the gypsum material is reduced, and the service life of the gypsum material is prolonged. Meanwhile, the breaking strength and the bonding strength of the gypsum material can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of gypsum material additives, and relates to a preparation method and process of an environment-friendly composite rubber powder for toughening gypsum. Background Art

[0002] Gypsum materials have the following advantages compared with other materials: (1) Low production energy consumption. The unit production energy consumption of the calcined gypsum used as the binder for producing gypsum plasterboard is 78% lower than that of cement. (2) Lightweight and heat-insulating. Using gypsum plasterboard as a partition wall, the weight is only 1 / 3 to 1 / 4 of that of a brick wall. At the same time, due to the porous structure of the gypsum board, its thermal conductivity coefficient is 0.30, and it has excellent heat-insulating performance compared with bricks (0.43) and concrete (1.63). (3) Excellent fire resistance. Since water of combination is released when gypsum is heated, its fire resistance limit can reach more than 2 hours. Good decorative function. The surface of the gypsum board is flat, and the boards can be firmly bonded together through the binder to form a seamless structure, with good building decoration effect. (4) Good workability. The gypsum board can be nailed, sawn, and glued, and the construction is very convenient. Using it for decoration can get rid of the traditional wet operation and greatly improve the construction efficiency. In recent years, the cumulative stockpile of industrial by-product gypsum in China has exceeded 300 million tons. The large-scale stockpile of a large amount of industrial by-product gypsum not only occupies land but also wastes resources. The acidic and other harmful substances contained are likely to pollute the surrounding environment, which has become an important factor restricting the sustainable development of flue gas desulfurization of coal-fired power plants and phosphate fertilizer enterprises in China. The comprehensive utilization of gypsum in multiple ways, on a large scale, and with high added value is the focus of current product development. At present, the utilization of gypsum mainly focuses on the construction industry, including gypsum boards, interior plastering materials, and cement retarders. Among them, gypsum self-leveling mortar, adhesive plaster, joint plaster, heat-insulating gypsum, etc. all require adhesives. The traditional liquid adhesives for the gypsum system are mainly copolymer adhesives, which are prepared by polycondensation reaction of polyvinyl alcohol and formaldehyde in an acidic medium and then amination. There is unreacted formaldehyde in the preparation process, so the pollution is large. In addition, the storage, transportation, and construction processes are not convenient. Therefore, developing an environment-friendly and efficient toughening gypsum environment-friendly rubber powder is of great significance for expanding the application fields of gypsum. Summary of the Invention

[0003] In order to solve the problems existing in the background technology, the present invention proposes a preparation method and process for a composite rubber powder for toughening gypsum putty. The composite rubber powder prepared by this method has an environmentally friendly and safe process, good construction performance and toughening characteristics. The technical solution adopted by the present invention to solve its technical problems includes the following steps: The first step of the present invention is to synthesize a copolymer emulsion, the second step is to compound the copolymer emulsion to form a mixed emulsion, and the third step is to form rubber powder by spray drying. The present invention prepares the composite rubber powder by controlling the reaction temperature, stirring speed and different feeding ratios. The production process of this rubber powder adopts an aqueous reaction system, which is green and environmentally friendly. After adding gypsum materials, it can effectively improve the toughness of gypsum materials and reduce the cracking of gypsum materials. At the same time, it can improve the flexural strength and bonding strength of gypsum materials. Specific embodiments The following further details the present invention through specific embodiments, but this should not be construed as limiting the scope of the present invention to the following examples. Without departing from the above method concept of the present invention, various substitutions or changes made according to common general knowledge and customary means in the art should be included in the scope of the present invention. The embodiments of the present invention are as follows: Example 1: Step 1: Preparation of copolymer emulsion. Configure sodium dodecyl sulfate: dodecylphenol polyoxyethylene ether: hydroxypropyl methylcellulose: vinyl acetate: vinyl versatate and deionized water as 0.5 kg: 0.5 kg: 1.5 kg: 4.5 kg: 4.5 kg: 88 kg, add them to a reaction kettle, heat up to 75°C and stir for 1 h to prepare a seed emulsion. For vinyl acetate: vinyl versatate: potassium persulfate with a mass ratio of 65 kg: 65 kg: 2 kg, slowly add it to the above-prepared seed emulsion and react for 3 h, then quickly cool down to 50°C, filter and discharge to obtain the emulsion. Step 2: Preparation of mixed emulsion. Add deionized water in proportion to a clean reaction kettle, heat up to 45°C, stir, slowly add 20 wt% of polyvinyl alcohol (PVA1788) based on the water volume in the reaction kettle, and then add 0.1 wt% of silicone defoamer based on the water volume in the reaction kettle. Heat up to 90°C and keep warm for 1 h to prepare a colloid. Sampling shows that the viscosity is 1850 Mpas and the solid content is 18.5%. Mix the above colloid and the emulsion prepared in Step 1 at a mass ratio of 5 kg: 80 kg, add water to adjust the viscosity to 70 Mpas, and heat up to 50°C. Step 3: Spray drying granulation. When the temperature of the feed inlet at the top of the spray drying tower rises to 140°C, transport the above mixed emulsion to the feed inlet at the top of the spray drying tower, atomize the dispersion into droplets through a high-speed centrifugal atomizing disk, quickly heat the micro-droplets with a high-temperature air stream, and at the same time supplement an isolating agent in the high-temperature air stream. The addition amount of the isolating agent is 5% of the weight of the mixed emulsion. When the micro-droplets are heated and become sticky, promptly adhere the isolating agent to the micro-droplets. Keep the temperature of the air flow at the air outlet of the spray drying tower at 80°C, quickly export the gas-solid mixture from the air outlet at the lower part of the spray drying tower, cool it down and introduce it into a large bag dust collector to separate the powder in the air flow. The separated powder is classified and sieved to obtain composite rubber powder 1.

[0004] Example 2: Step 1: Preparation of copolymer emulsion. Configure sodium dodecyl sulfate: dodecylphenol polyoxyethylene ether: hydroxypropyl methylcellulose: vinyl acetate: vinyl versatate and deionized water as 1 kg: 1.5 kg: 3 kg: 5 kg: 5 kg: 90 kg. Add them to a reaction kettle, heat up to 85 °C and stir for 0.5 h to prepare a seed emulsion. For vinyl acetate: vinyl versatate: potassium persulfate with a mass ratio of 85 kg: 85 kg: 3 kg, slowly add it to the above-prepared seed emulsion and react for 4 h, then quickly cool down to 55 °C, filter and discharge to obtain the emulsion. Step 2: Preparation of mixed emulsion. Add deionized water in proportion to a clean reaction kettle, heat up to 55 °C, stir, slowly add 25 wt% of polyvinyl alcohol (PVA1788) based on the amount of water in the reaction kettle, and then add 0.5 wt% of silicone defoamer based on the amount of water in the reaction kettle. Heat up to 95 °C and keep warm for 0.5 h to prepare a colloid. Take a sample and measure the viscosity to be 2050 Mpas and the solid content to be 21.5%. Mix the above colloid and the emulsion prepared in Step 1 at a mass ratio of 9 kg: 88 kg, add water to adjust the viscosity to 200 Mpas, and heat up to 52 °C. Step 3: Spray drying and granulation. When the temperature of the feed inlet at the top of the spray drying tower is heated up to 150 °C, transport the above mixed emulsion to the feed inlet at the top of the spray drying tower. Atomize the dispersion into droplets through a high-speed centrifugal atomization disk, quickly heat the micro-droplets with a high-temperature gas stream, and at the same time supplement an isolating agent in the high-temperature gas stream. The addition amount of the isolating agent is 7% of the weight of the mixed emulsion. When the micro-droplets are heated and become sticky, promptly adhere the isolating agent to the micro-droplets. Keep the temperature of the air flow at the air outlet of the spray drying tower at 85 °C, quickly export the gas-solid mixture from the air outlet at the lower part of the spray drying tower, cool it down and introduce it into a large bag dust collector to separate the powder in the air flow. The separated powder is sieved through classification to obtain composite rubber powder 2.

[0005] Example 3: Step 1: Preparation of copolymer emulsion. Prepare a mixture of sodium dodecyl sulfate: dodecylphenol polyoxyethylene ether: hydroxypropyl methylcellulose: vinyl acetate: vinyl versatate and deionized water in the ratio of 1 kg: 1.2 kg: 5 kg: 4.8 kg: 4.8 kg: 85 kg. Add it to a reaction kettle, heat up to 80 °C and stir for 0.8 h to prepare a seed emulsion. Then, slowly add a mixture of vinyl acetate: vinyl versatate: potassium persulfate with a mass ratio of 70 kg: 70 kg: 1.5 kg to the above-prepared seed emulsion and react for 3.5 h. Rapidly cool down to 52 °C, filter and discharge to obtain the emulsion. Step 2: Preparation of mixed emulsion. Add deionized water to a clean reaction kettle in proportion, heat up to 50 °C, stir, and slowly add 23 wt% of polyvinyl alcohol (PVA1788) based on the amount of water in the reaction kettle. Then add 0.3 wt% of defoamer (silicone defoamer) based on the amount of water in the reaction kettle, heat up to 92 °C, and keep warm for 1.5 h to prepare a colloid. Sampling shows that the viscosity is 2010 Mpas and the solid content is 20.5%. Mix the above colloid and the emulsion prepared in Step 1 in a mass ratio of 8 kg: 85 kg, add water to adjust the viscosity to 150 Mpas, and heat up to 52 °C. Step 3: Spray drying and granulation. When the temperature of the feed inlet at the top of the spray drying tower is heated up to 145 °C, transport the above mixed emulsion to the feed inlet at the top of the spray drying tower, atomize the dispersion liquid through a high-speed centrifugal atomization disk, rapidly heat the micro-droplets with a high-temperature gas stream, and at the same time supplement an isolating agent into the high-temperature gas stream. The addition amount of the isolating agent is 6% of the weight of the mixed emulsion. When the micro-droplets are heated and become sticky, promptly adhere the isolating agent to the micro-droplets. Keep the temperature of the air flow at the outlet of the spray drying tower at 81 °C, rapidly export the gas-solid mixture from the outlet at the lower part of the spray drying tower, cool it down and introduce it into a large bag dust collector to separate the powder in the air flow. The separated powder is classified and sieved to obtain composite rubber powder 3.

[0006] Example 4: Step 1: Preparation of copolymer emulsion. Configure sodium dodecyl sulfate: dodecylphenol polyoxyethylene ether: hydroxypropyl methylcellulose: vinyl acetate: vinyl versatate and deionized water as 1.5 kg: 1.5 kg: 1.5 kg: 5 kg: 4.5 kg: 85 kg: 90 kg, add them to a reaction kettle, heat up to 80 °C and stir for 0.5 h to prepare a seed emulsion. For vinyl acetate: vinyl versatate: potassium persulfate with a mass ratio of 70 kg: 70 kg: 2.5 kg, slowly add it to the above-prepared seed emulsion and react for 3 h, then quickly cool down to 55 °C, filter and discharge to obtain the emulsion. Step 2: Preparation of mixed emulsion. Add deionized water in proportion to a clean reaction kettle, heat up to 50 °C, stir, slowly add 25 wt% of the water in the reaction kettle of polyvinyl alcohol (PVA1788), and then add 0.1 wt% of the water in the reaction kettle of defoamer (silicone defoamer), heat up to 90 °C and keep warm for 1.5 hours to prepare a colloid. Take a sample and measure the viscosity to be 1870 Mpas and the solid content to be 17.5%. Mix the above colloid and the emulsion prepared in Step 1 at a mass ratio of 5 kg: 80 kg, add water to adjust the viscosity to 100 Mpas, and heat up to 55 °C. Step 3: Spray drying and granulation. When the temperature of the feed inlet at the top of the spray drying tower rises to 140 °C, transport the above mixed emulsion to the feed inlet at the top of the spray drying tower, atomize the dispersion through a high-speed centrifugal atomization disk, quickly heat the micro droplets with a high-temperature gas stream, and at the same time supplement an isolating agent in the high-temperature gas stream. The addition amount of the isolating agent is 5% of the weight of the mixed emulsion. When the micro droplets are heated and become sticky, timely adhere the isolating agent to the micro droplets. Keep the temperature of the air flow at the outlet of the spray drying tower at 75 °C, quickly export the gas-solid mixture from the outlet at the lower part of the spray drying tower, cool it down and then introduce it into a large bag dust collector to separate the powder in the air flow. The separated powder is passed through classification and sieving to obtain composite rubber powder 4.

[0007] Example 5: Step 1: Preparation of copolymer emulsion. Configure sodium dodecyl sulfate: dodecylphenol polyoxyethylene ether: hydroxypropyl methylcellulose: vinyl acetate: vinyl versatate and deionized water as 1 kg: 1 kg: 4 kg: 5 kg: 5 kg: 90 kg, add them to a reaction kettle, heat up to 85 °C and stir for 1 h to prepare a seed emulsion. For vinyl acetate: vinyl versatate: potassium persulfate with a mass ratio of 80 kg: 70 kg: 2.5 kg, slowly add it to the above-prepared seed emulsion and react for 4 h, then quickly cool down to 55 °C, filter and discharge to obtain the emulsion. Step 2: Preparation of mixed emulsion. Add deionized water in proportion to a clean reaction kettle, heat up to 50 °C, stir, slowly add 25 wt% of the water volume in the reaction kettle of polyvinyl alcohol (PVA1788), and then add 0.1 - 0.5 wt% of defoamer (silicone defoamer) based on the water volume in the reaction kettle, heat up to 95 °C and keep warm for 1.5 h to prepare a colloid. Sampling shows that the viscosity is 2200 Mpas and the solid content is 20%. Mix the above colloid and the emulsion prepared in Step 1 at a mass ratio of 7 kg: 86 kg, add water to adjust the viscosity to 160 Mpas, and heat up to 55 °C. Step 3: Spray drying and granulation. When the temperature of the feed inlet at the top of the spray drying tower rises to 150 °C, transport the above mixed emulsion to the feed inlet at the top of the spray drying tower, atomize the dispersion into droplets through a high-speed centrifugal atomizing disk, quickly heat the micro-droplets with a high-temperature gas stream, and at the same time supplement an isolating agent in the high-temperature gas stream. The addition amount of the isolating agent is 7% of the weight of the mixed emulsion. When the micro-droplets are heated and become sticky, timely adhere the isolating agent to the micro-droplets. Keep the temperature of the air flow at the outlet of the spray drying tower at 80 °C, quickly export the gas-solid mixture from the outlet at the lower part of the spray drying tower, cool it down and then introduce it into a large bag dust collector to separate the powder in the air flow. The separated powder passes through classification and sieving to obtain composite rubber powder 5. To test the toughening effect of this environmentally friendly composite rubber powder on gypsum, mix 50 g of composite rubber powder, 450 g of gypsum powder and 500 g of quartz sand (200 mesh), add water to the standard consistency, stir evenly, then while slowly stirring, ladle the slurry into a test mold and remove air bubbles as required. After final setting and demolding, specimens are obtained. Add composite rubber powder 1, composite rubber powder 2, composite rubber powder 3, composite rubber powder 4, composite rubber powder 5 to gypsum powder respectively according to the above process to prepare specimens 1, specimen 2, specimen 3, specimen 4, specimen 5; mix 500 g of gypsum powder and 500 g of quartz sand, and prepare specimens without adding rubber powder according to the above similar process, and label them as specimen 0. Put all the above specimens into an environment of (20 ± 2) °C and relative humidity (90 ± 5)% for curing and test the strength. Use a mold frame with a thickness of 6 mm and a size of 40 * 40 mm, and the environmental wind speed is less than 0.5 m / s to conduct a crack resistance experiment by simulating the actual construction thickness.

Claims

1. A preparation method and process of an environmentally friendly composite rubber powder for toughening gypsum, characterized in that It includes the following steps: Step 1: Preparation of copolymer emulsion. Add a certain amount of sodium dodecyl sulfate, polyoxyethylene dodecyl phenyl ether, hydroxypropyl methylcellulose, vinyl acetate, vinyl versatate and deionized water into a reaction kettle, heat up to 75 - 85°C and stir for 0.5 - 1 h to prepare a seed emulsion. Slowly add vinyl acetate, vinyl versatate and initiator potassium persulfate into the above-prepared seed emulsion and react for 3 - 4 h, then quickly cool down to 50 - 55°C, filter and discharge to obtain the emulsion. Step 2: Preparation of mixed emulsion. Add deionized water into the reaction kettle, heat up to 45 - 55°C, slowly add 20 - 25 wt% of the water amount in the reaction kettle of polyvinyl alcohol and stir, then add 0.1 - 0.5 wt% of defoamer (silicone defoamer) based on the water amount in the reaction kettle, heat up to 90 - 95°C and keep warm for 0.5 - 1.5 hours to prepare a colloid. Mix the above colloid and the copolymer emulsion prepared in Step 1, and add water to adjust the viscosity. Step 3: Spray drying granulation. Transport the above mixed emulsion to the feed port at the top of the spray drying tower, atomize the dispersion liquid into micro droplets through a high-speed centrifugal atomizing disk, quickly heat the micro droplets with a high-temperature air stream, and at the same time supplement an isolating agent in the high-temperature air stream, and timely adhere the isolating agent to the micro droplets when the micro droplets are heated to generate viscosity. Set the temperature of the air flow at the outlet of the spray drying tower to 75°C - 85°C, quickly export the gas-solid mixture from the outlet at the lower part of the spray drying tower, cool it down and then introduce it into a large bag dust collector to separate and classify and screen the powder in the air flow to obtain the composite rubber powder.

2. According to the preparation method and process of an environmentally friendly composite rubber powder for toughening gypsum described in claim 1, the characteristics of Step 1 are as follows: The ratio of sodium dodecyl sulfate: polyoxyethylene dodecyl phenyl ether: hydroxypropyl methylcellulose: vinyl acetate: vinyl versatate and deionized water is configured as 0.5 - 1.5 kg: 0.5 - 1.5 kg: 1.5 - 5 kg: 4.5 - 5 kg: 4.5 - 5 kg: 85 - 90 kg; Use a compound surfactant of sodium dodecyl sulfate and polyoxyethylene dodecyl phenyl ether, and the mass ratio of the two is 1:1 - 1:1.5; Use hydroxypropyl methylcellulose as a viscosity regulator; The mass ratio of added vinyl acetate: vinyl versatate: potassium persulfate is 65 - 85 kg: 65 - 85 kg: 1.5 - 3 kg.

3. According to the preparation method and process of an environmentally friendly composite rubber powder for toughening gypsum described in claim 1, the characteristics of Step 3 are as follows: The temperature of the feed port at the top of the spray drying tower is 140 - 150°C; The diameter of the atomized micro droplets is 10 - 100 microns; The addition amount of the isolating agent is 5 - 7% of the weight of the mixed emulsion.