Lightweight thermal insulation material and production process thereof

Abstract

The invention relates to a lightweight thermal insulation material and a production process thereof, and the production process is characterized by comprising the following steps: preparing cement mortar: uniformly mixing 90-100 parts by weight of magnesium oxide powder, 65-75 parts by weight of a magnesium sulfate solution, 15-19 parts by weight of fly ash, 1-2.5 parts by weight of straw fiber, 0.5-1.2 parts by weight of sodium silicate and 0.05-0.12 part by weight of citric acid to prepare the cement mortar, the density of the magnesium sulfate solution is 1.21 g / cm < 3 >, and the Baume degree Be is 24.75 degrees; preparing foam: taking 5 parts by weight of lauryl sodium sulfate, adding 60 parts by weight of water for dilution, adding 1 part by weight of polyamine modified nano silicon dioxide, and foaming by using a foaming machine; and preparing the thermal insulation material: taking 100 parts by volume of cement mortar, adding 350-400 parts by volume of prefabricated foam, fully stirring, pumping into a forming mold, curing, forming, demolding, and curing to obtain a finished product. The product is light in weight, high in strength, heat-insulating, fireproof, flame-retardant, green, environment-friendly, free of efflorescence and frost accumulation, easy in raw material obtaining and high in cost performance, and is a novel wall material worthy of popularization.

Description

Technical Field

[0001] The invention relates to the field of wall thermal insulation materials, and in particular to a lightweight thermal insulation material and a production process. Background Art

[0002] Thermal insulation materials are the key to building energy conservation. Foamed concrete is a new type of lightweight thermal insulation material containing a large number of closed pores inside. It has the advantages of light weight, heat insulation, sound insulation, fire resistance, and impermeability. It has been widely studied in recent years. Magnesium oxysulfate cement, as a new type of magnesium cementitious material, was proposed by Belgian scholars in 1957. It is a MgO-MgSO4-H2O ternary cementing system composed of active MgO and a certain concentration of MgSO4 solution. Compared with traditional silicate cement, it has the advantages of low production temperature and low energy consumption. Compared with traditional magnesium oxychloride cement, it retains the fireproof, heat preservation, durability and environmental protection characteristics of magnesium oxychloride cement, and avoids the hidden danger of moisture absorption and brine return of magnesium oxychloride cement. Therefore, the use of magnesium oxysulfate cement to replace silicate cement and magnesium oxychloride cement to prepare foamed concrete has broad market application potential. The applicant found that the raw materials selected in the magnesium oxysulfate wallboard production process disclosed in the prior art generally use excessive magnesium sulfate. This part of magnesium sulfate does not participate in the MgO reaction and seeps out from the wall over time, resulting in the phenomenon of "frost" on the wall. The anionic surfactant sodium dodecyl sulfate is cheap, has good foaming fineness and foaming amount, but poor foam stability. Adding nanoparticles can improve foam stability, but nanoparticles tend to agglomerate, resulting in insignificant improvement in foam quality. The applicant found that adding nanoparticles modified by polydopamine significantly improved foam quality. The reason may be that polydopamine has a large amount of catechol structures, and its super strong adhesion performance is used to wrap nanoparticles, making the nanoparticles negatively charged. The strong electrostatic repulsion makes the nanoparticles wrapped by polydopamine difficult to agglomerate, increasing the dispersibility of the nanoparticles, and the hydrophilic properties of the nanoparticles modified by polydopamine are greatly improved, which can be well adsorbed on the foam surface, increase the mechanical strength of the foam, thereby improving the stability of the foam. Summary of the invention

[0003] The purpose of the present invention is to provide a lightweight thermal insulation material and a production process in view of the above problems.

[0004] The present invention provides a lightweight thermal insulation material and a production process, which is characterized by comprising the following steps:

[0005] Preparation of cement mortar: by weight, take 90-100 parts of magnesium oxide powder, 65-75 parts of magnesium sulfate solution, 15-19 parts of fly ash, 1-2.5 parts of straw fiber, 0.5-1.2 parts of sodium silicate, and 0.05-0.12 parts of citric acid, wherein the density of the magnesium sulfate solution is 1.21 g / cm3, and the Baume degree Be=24.75°; first add the modifier to the magnesium sulfate solution and stir evenly, then add magnesium oxide and stir for 2-4 minutes, and after fully hydrating, add fly ash and straw fiber in turn and mix evenly to obtain cement mortar;

[0006] Prefabricated foam: by weight, take 5 parts of sodium lauryl sulfate, add 60 parts of water to dilute, and then use a foaming machine to make foam;

[0007] Preparation of thermal insulation materials: by volume, 100 parts of cement mortar are added to 350-400 parts of prefabricated foam, and after sufficient stirring, the mixture is pumped into a molding mold, and after solidification and molding, the mixture is demoulded and cured to obtain a finished product.

[0008] Another lightweight thermal insulation material and production process of the present invention is characterized by comprising the following steps:

[0009] Preparation of cement mortar: by weight, take 90-100 parts of magnesium oxide powder, 65-75 parts of magnesium sulfate solution, 15-19 parts of fly ash, 1-2.5 parts of straw fiber, 0.5-1.2 parts of sodium silicate, and 0.05-0.12 parts of citric acid, wherein the density of the magnesium sulfate solution is 1.21 g / cm3, and the Baume degree Be=24.75°; first add the modifier to the magnesium sulfate solution and stir evenly, then add magnesium oxide and stir for 2-4 minutes, and after fully hydrating, add fly ash and straw fiber in turn and mix evenly to obtain cement mortar;

[0010] Prefabricated foam: by weight, take 5 parts of sodium dodecyl sulfate, add 60 parts of water to dilute, then add 1 part of polypadoamine-modified nano-silicon dioxide, and use a foaming machine to make foam;

[0011] Preparation of thermal insulation materials: by volume, 100 parts of cement mortar are added to 350-400 parts of prefabricated foam, and after sufficient stirring, the mixture is pumped into a molding mold, and after solidification and molding, the mixture is demoulded and cured to obtain a finished product.

[0012] Preferably, polypdamine-modified nano-silica is prepared as follows: by weight, 1 part of nano-silica, 0.04 parts of sodium hexametaphosphate, 150 parts of deionized water, 0.18 parts of Tris, and 0.3 parts of dopamine hydrochloride are taken; the nano-silica and sodium hexametaphosphate are added to deionized water and ultrasonically dispersed for 1 hour to obtain a stable nano-silica suspension; then Tris is added to the suspension to obtain a Tris buffer solution; the pH is adjusted to 8.5 with 5% hydrochloric acid; finally, dopamine hydrochloride is added; after magnetic stirring at room temperature for 8 hours, the mixed solution is separated by a centrifuge and dried to obtain polypdamine-modified nano-silica.

[0013] Preferably, the particle size of the nano-silicon dioxide is 10-20 nm.

[0014] Compared with the prior art, it has the following beneficial effects:

[0015] 1. The present invention solves the problem of "frosting" on the surface of the existing magnesium oxysulfate wall over time by reducing the weight ratio of magnesium sulfate;

[0016] 2. The present invention uses a certain proportion of sodium silicate and citric acid for comprehensive modification to adjust the cementing speed, early strength and water resistance, which is better than using sodium silicate alone;

[0017] 3. The present invention selects anionic surfactants and adds nanoparticles modified by polydopamine, and the obtained microfoam is rich and delicate, cannot be distinguished by the naked eye, has a high closed-cell rate, is evenly dispersed, has high strength, and has good durability. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below through embodiments.

[0019] Example 1

[0020] The invention discloses a lightweight thermal insulation material, characterized in that:

[0021] The following steps are involved:

[0022] Preparation of cement mortar: by weight, take 90 parts of magnesium oxide powder, 65 parts of magnesium sulfate solution, 15 parts of fly ash, 1 part of straw fiber, 0.5 parts of sodium silicate, and 0.05 parts of citric acid, wherein the density of the magnesium sulfate solution is 1.21 g / cm3, and the Baume degree Be=24.75°; first add the modifier into the magnesium sulfate solution and stir evenly, then add magnesium oxide and stir for 2-4 minutes, and after it is fully hydrated, add fly ash and straw fiber in turn and mix evenly to obtain cement mortar.

[0023] Prefabricated foam: by weight, take 5 parts of sodium lauryl sulfate, add 60 parts of water to dilute, and then use a foaming machine to make foam;

[0024] Preparation of thermal insulation materials: By volume, take 100 parts of cement mortar and add 350 parts of prefabricated foam. After fully stirring, pump it into the molding mold. After solidification and molding, demold and cure it. Initially cure it in the natural environment for 5 to 7 days, then put it into the warehouse and carry out final curing for 20 days.

[0025] Example 2

[0026] The difference from Example 1 is:

[0027] Preparation of cement mortar: by weight, take 95 parts of magnesium oxide powder, 70 parts of magnesium sulfate solution, 17 parts of fly ash, 1.7 parts of straw fiber, 0.8 parts of sodium silicate, and 0.08 parts of citric acid.

[0028] Preparation of thermal insulation material: by volume, add 375 parts of prefabricated foam to 100 parts of cement mortar.

[0029] Example 3

[0030] The difference from Example 1 is:

[0031] Preparation of cement mortar: by weight, take 100 parts of magnesium oxide powder, 75 parts of magnesium sulfate solution, 19 parts of fly ash, 2.5 parts of straw fiber, 1.2 parts of sodium silicate, and 0.12 parts of citric acid.

[0032] Preparation of thermal insulation materials: by volume, add 100 parts of cement mortar to 400 parts of prefabricated foam.

[0033] Example 4

[0034] The invention discloses a lightweight thermal insulation material, characterized in that:

[0035] The following steps are involved:

[0036] Preparation of cement mortar: by weight, take 90 parts of magnesium oxide powder, 65 parts of magnesium sulfate solution, 15 parts of fly ash, 1 part of straw fiber, 0.5 parts of sodium silicate, and 0.05 parts of citric acid, wherein the density of the magnesium sulfate solution is 1.21 g / cm3, and the Baume degree Be=24.75°; first add the modifier into the magnesium sulfate solution and stir evenly, then add magnesium oxide and stir for 2-4 minutes, and after it is fully hydrated, add fly ash and straw fiber in turn and mix evenly to obtain cement mortar.

[0037] Preparation of polypdamine-modified nano-silica: by weight, 1 part of nano-silica, 0.04 parts of sodium hexametaphosphate, 150 parts of deionized water, 0.18 parts of Tris, and 0.3 parts of dopamine hydrochloride, wherein the particle size of the nano-silica is 10-20 nm, nano-silica and sodium hexametaphosphate are added to deionized water for ultrasonic dispersion for 1 hour to obtain a stable nano-silica suspension, then Tris is added to the suspension to obtain a Tris buffer, the pH is adjusted to 8.5 with 5% hydrochloric acid, and finally dopamine hydrochloride is added, and after magnetic stirring at room temperature for 8 hours, the mixed solution is separated by a centrifuge and dried to obtain polypdamine-modified nano-silica;

[0038] Prefabricated foam: by weight, take 5 parts of sodium dodecyl sulfate, add 60 parts of water to dilute, then add 1 part of polypadoamine-modified nano-silicon dioxide, and use a foaming machine to make foam;

[0039] Preparation of thermal insulation materials: By volume, take 100 parts of cement mortar and add 350 parts of prefabricated foam. After fully stirring, pump it into the molding mold. After solidification and molding, demold and cure it. Initially cure it in the natural environment for 5 to 7 days, then put it into the warehouse and carry out final curing for 20 days.

[0040] Example 5

[0041] The difference from Example 4 is:

[0042] Preparation of cement mortar: by weight, take 95 parts of magnesium oxide powder, 70 parts of magnesium sulfate solution, 17 parts of fly ash, 1.7 parts of straw fiber, 0.8 parts of sodium silicate, and 0.08 parts of citric acid.

[0043] Preparation of thermal insulation material: by volume, add 375 parts of prefabricated foam to 100 parts of cement mortar.

[0044] Example 6

[0045] The difference from Example 4 is:

[0046] Preparation of cement mortar: by weight, take 100 parts of magnesium oxide powder, 75 parts of magnesium sulfate solution, 19 parts of fly ash, 2.5 parts of straw fiber, 1.2 parts of sodium silicate, and 0.12 parts of citric acid.

[0047] Preparation of thermal insulation materials: by volume, add 100 parts of cement mortar to 400 parts of prefabricated foam.

[0048] Comparative Example

[0049] Preparation of cement mortar: by weight, take 95 parts of magnesium oxide powder, 88 parts of magnesium sulfate powder, 17 parts of fly ash, 1.7 parts of straw fiber, and 0.8 parts of sodium silicate, wherein the density of the magnesium sulfate solution is 1.21 g / cm3, and the Baume degree Be=24.75°; first add the modifier into the magnesium sulfate solution and stir evenly, then add magnesium oxide and stir for 2-4 minutes, and after it is fully hydrated, add fly ash and straw fiber in turn and mix evenly to obtain cement mortar.

[0050] Prefabricated foam: by weight, take 5 parts of sodium lauryl sulfate, add 60 parts of water to dilute, and then use a foaming machine to make foam;

[0051] Preparation of thermal insulation materials: By volume, take 100 parts of cement mortar and add 375 parts of prefabricated foam. After fully stirring, pump it into the molding mold. After solidification and molding, demold and cure it. Initially cure it in the natural environment for 5 to 7 days, then put it into the warehouse and carry out final curing for 20 days.

[0052] The test results of 6 embodiments and 1 comparative example are shown in the following table:

[0053]

[0054] The density of the lightweight environmentally friendly thermal insulation material of this application is 220-260kg / m 3 , compressive strength 0.65-0.87MPa, thermal conductivity less than 0.08W / (m·K), volume water absorption less than 1.80%, performance indicators are better than GB / T 33500-2017 external wall insulation foam ceramics, can be used for external wall insulation. The product is light in weight, high in strength, heat-insulating, fire-retardant, green and environmentally friendly, no halogen return, no frost accumulation, easy to obtain raw materials, high cost performance, is a new type of wall material worthy of promotion.

Claims

1. A lightweight thermal insulation material and production process, characterized in that: The following steps are involved: Preparation of cement mortar: by weight, take 90-100 parts of magnesium oxide powder, 65-75 parts of magnesium sulfate solution, 15-19 parts of fly ash, 1-2.5 parts of straw fiber, 0.5-1.2 parts of sodium silicate, and 0.05-0.12 parts of citric acid, wherein the density of the magnesium sulfate solution is 1.21 g / cm3, and the Baume degree Be=24.75°; first add the modifier to the magnesium sulfate solution and stir evenly, then add magnesium oxide and stir for 2-4 minutes, and after fully hydrating, add fly ash and straw fiber in turn and mix evenly to obtain cement mortar; Prefabricated foam: by weight, take 5 parts of sodium lauryl sulfate, add 60 parts of water to dilute, and then use a foaming machine to make foam; Preparation of thermal insulation materials: by volume, 100 parts of cement mortar are added to 350-400 parts of prefabricated foam, and after sufficient stirring, the mixture is pumped into a molding mold, and after solidification and molding, the mixture is demoulded and cured to obtain a finished product.

2. A lightweight thermal insulation material and production process, characterized in that: The following steps are involved: Preparation of cement mortar: by weight, take 90-100 parts of magnesium oxide powder, 65-75 parts of magnesium sulfate solution, 15-19 parts of fly ash, 1-2.5 parts of straw fiber, 0.5-1.2 parts of sodium silicate, and 0.05-0.12 parts of citric acid, wherein the density of the magnesium sulfate solution is 1.21 g / cm3, and the Baume degree Be=24.75°; first add the modifier to the magnesium sulfate solution and stir evenly, then add magnesium oxide and stir for 2-4 minutes, and after fully hydrating, add fly ash and straw fiber in turn and mix evenly to obtain cement mortar; Prefabricated foam: by weight, take 5 parts of sodium dodecyl sulfate, add 60 parts of water to dilute, then add 1 part of polypadoamine-modified nano-silicon dioxide, and use a foaming machine to make foam; Preparation of thermal insulation materials: by volume, 100 parts of cement mortar are added to 350-400 parts of prefabricated foam, and after sufficient stirring, the mixture is pumped into a molding mold, and after solidification and molding, the mixture is demoulded and cured to obtain a finished product.

3. A lightweight thermal insulation material and production process as claimed in claim 2, characterized in that: Preparation of polypdamine-modified nano-silica: by weight, take 1 part of nano-silica, 0.04 parts of sodium hexametaphosphate, 150 parts of deionized water, 0.18 parts of Tris, and 0.3 parts of dopamine hydrochloride. Add the nano-silica and sodium hexametaphosphate into deionized water and ultrasonically disperse them for 1 hour to obtain a stable nano-silica suspension. Then add Tris to the suspension to obtain Tris buffer, adjust the pH to 8.5 with 5% hydrochloric acid, and finally add dopamine hydrochloride. After magnetic stirring at room temperature for 8 hours, separate the mixed liquid by centrifuge and dry it to obtain polypdamine-modified nano-silica.

4. A lightweight thermal insulation material and production process as claimed in claim 2 or 3, characterized in that: The nano silicon dioxide has a size of 10-20 nm.

Images