A putty gypsum and a method for producing the same

Abstract

The application belongs to the field of building materials, and particularly relates to a plastering gypsum and a preparation method thereof. The plastering gypsum comprises dry materials and water; the dry materials comprise, in terms of weight fractions, 30-50 parts of building gypsum powder, 40-60 parts of sand, 0-20 parts of heavy calcium powder, 0.1-0.5 parts of a water-retaining agent, 0.01-0.1 parts of a thixotropic lubricant and 0.2-1.5 parts of a setting time stabilizer; the setting time stabilizer comprises tartaric acid, anhydrite powder, a sulfate and a protein-based retarder, the sulfate is aluminum sulfate and / or potassium sulfate, and the mass ratio of the tartaric acid, the anhydrite powder, the sulfate and the protein-based retarder is 1:(5-25):(2-10):(0.3-1.5). The plastering gypsum is neutral and has excellent environmental adaptability.

Description

Technical Field

[0001] This invention belongs to the field of building materials, and in particular relates to a plastering gypsum and its preparation method. Background Technology

[0002] Plastering gypsum is a material used for plastering interior walls and ceilings of buildings. It is mainly made of building gypsum, cement, lime, retarders, water-retaining agents and other materials mixed with water.

[0003] Traditional plastering gypsum currently suffers from two main problems: first, it becomes alkaline after mixing with water, easily irritating the skin and respiratory tract, thus requiring protective measures during construction; second, it has poor environmental adaptability, exhibiting rapid setting when mixed with alkaline contaminants (such as cement and lime) or by cross-contamination during production or at construction sites (including accelerators like dihydrate gypsum). Typically, to ensure sufficient workability during actual construction, the initial setting time of plastering gypsum needs to be extended as much as possible. However, this, in turn, affects other properties of the plastering gypsum, such as strength and resistance to ductile cracking. How to ensure an appropriate initial workability time for plastering gypsum and maintain a stable setting time under different contaminant conditions is a major challenge that needs to be addressed in the development of plastering gypsum products. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a plastering gypsum and a method for preparing the same. The plastering gypsum provided by the present invention is neutral and has excellent environmental adaptability.

[0005] This invention provides a plastering compound, comprising a dry material and water; the dry material, by weight, comprises:

[0006] 30-50 parts of building plaster powder;

[0007] 40-60 parts sand;

[0008] 0-20 parts of heavy calcium carbonate powder;

[0009] Water-retaining agent 0.1~0.5 parts;

[0010] Thixotropic lubricant, 0.01~0.1 parts;

[0011] Setting time stabilizer: 0.2-1.5 parts;

[0012] The setting time stabilizer includes tartaric acid, anhydrite powder, sulfate and protein retarder, wherein the sulfate is aluminum sulfate and / or potassium sulfate, and the mass ratio of tartaric acid, anhydrite powder, sulfate and protein retarder is 1:(5~25):(2~10):(0.3~1.5).

[0013] Preferably, the building gypsum powder is natural gypsum powder; the particle size of the building gypsum powder is 50~150 mesh.

[0014] Preferably, the particle size of the sand is 30-200 mesh.

[0015] Preferably, the particle size of the heavy calcium carbonate powder is 150-350 mesh.

[0016] Preferably, the water-retaining agent is a cellulose ether.

[0017] Preferably, the thixotropic lubricant is starch ether.

[0018] Preferably, the tartaric acid is L-tartaric acid.

[0019] Preferably, the particle size of the anhydrite powder is 1~50μm.

[0020] Preferably, the mass ratio of the dry material to water is 10:(2~5).

[0021] This invention provides a method for preparing the plaster described in the above technical solution, comprising the following steps:

[0022] Building gypsum powder, sand, heavy calcium carbonate powder, water-retaining agent, thixotropic lubricant and setting time stabilizer are mixed to obtain dry material;

[0023] The dry material is mixed with water to obtain plaster.

[0024] Compared with the prior art, the present invention provides a plastering gypsum and its preparation method. The plastering gypsum provided by the present invention comprises dry materials and water; by weight, the dry materials comprise: 30-50 parts of building gypsum powder, 40-60 parts of sand, 0-20 parts of heavy calcium carbonate powder, 0.1-0.5 parts of water-retaining agent, 0.01-0.1 parts of thixotropic lubricant, and 0.2-1.5 parts of setting time stabilizer; the setting time stabilizer comprises tartaric acid, anhydrite powder, sulfate and protein retarder, wherein the sulfate is aluminum sulfate and / or potassium sulfate, and the mass ratio of tartaric acid, anhydrite powder, sulfate and protein retarder is 1:(5-25):(2-10):(0.3-1.5). The plaster provided by this invention completely eliminates alkaline components such as cement and lime. By compounding plaster with non-alkaline additives, the pH value of the slurry is stabilized at 6.5~7.5, thus solving the problem of alkaline irritation from the source. Based on this, the present invention introduces two retarding components (tartaric acid and protein-based retarder) and two accelerating components (anhydrite powder and aluminum / potassium sulfate) into plaster to form a dual-response setting regulation system: tartaric acid, due to the low degree of dissociation of its carboxyl groups under neutral conditions, has a weak inhibitory effect on gypsum hydration. Anhydrite powder and aluminum / potassium sulfate, in the presence of protein-based retarder, can stabilize the setting time, thus ensuring the stability of the open time. When alkaline contaminants such as cement or lime are present, the alkaline environment causes the complete dissociation of tartaric acid carboxyl groups, which strongly adsorb onto the surface of gypsum crystals through chelation, inhibiting the dissolution of Ca²⁺ ions and slowing down the hydration process. At the same time, the effect of sulfate ions in the accelerating component on forming gypsum crystal nuclei with Ca²⁺ in alkaline substances is weakened. The synergy of the two can effectively reduce the fluctuation of setting time and avoid rapid setting accidents. Furthermore, the building gypsum powder in the plaster of this invention is preferably made entirely of natural gypsum, which is free of active impurities and has low levels of heavy metals, radioactive substances and harmful ions, thereby further improving the quality stability of the product. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a plastering compound, comprising a dry material and water; the dry material, by weight, comprises:

[0027] 30-50 parts of building plaster powder;

[0028] 40-60 parts sand;

[0029] 0-20 parts of heavy calcium carbonate powder;

[0030] Water-retaining agent 0.1~0.5 parts;

[0031] Thixotropic lubricant, 0.01~0.1 parts;

[0032] Setting time stabilizer: 0.2-1.5 parts;

[0033] The setting time stabilizer includes tartaric acid, anhydrite powder, sulfate and protein retarder, wherein the sulfate is aluminum sulfate and / or potassium sulfate, and the mass ratio of tartaric acid, anhydrite powder, sulfate and protein retarder is 1:(5~25):(2~10):(0.3~1.5).

[0034] In the plaster provided by the present invention, the building plaster powder is preferably a building plaster powder prepared from natural plaster; the particle size of the building plaster powder is preferably 50-150 mesh, more preferably 100-120 mesh.

[0035] In the plaster provided by the present invention, the content of the building plaster powder in the dry material can specifically be 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, or 50 parts by weight.

[0036] In the plaster provided by the present invention, the sand is preferably washed sand; the particle size of the sand is preferably 30-200 mesh, more preferably 40-140 mesh, and specifically can be 40-70 mesh, 50-100 mesh or 70-140 mesh.

[0037] In the plaster provided by the present invention, the content of sand in the dry material can specifically be 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, or 60 parts by weight.

[0038] In the plaster provided by the present invention, the particle size of the heavy calcium carbonate powder is preferably 150-350 mesh, specifically 200 mesh or 325 mesh.

[0039] In the plaster provided by the present invention, the content of heavy calcium carbonate powder in the dry material can be specifically 0 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, or 20 parts by weight.

[0040] In the plaster provided by the present invention, the water-retaining agent is preferably a cellulose ether, including but not limited to hydroxyethyl methylcellulose (HEMC) and / or hydroxypropyl methylcellulose (HPMC).

[0041] In the plaster provided by the present invention, the content of the water-retaining agent in the dry material can specifically be 0.1 parts by weight, 0.12 parts by weight, 0.15 parts by weight, 0.17 parts by weight, 0.2 parts by weight, 0.23 parts by weight, 0.25 parts by weight, 0.27 parts by weight, 0.3 parts by weight, 0.32 parts by weight, 0.35 parts by weight, 0.37 parts by weight, 0.4 parts by weight, 0.42 parts by weight, 0.45 parts by weight, 0.47 parts by weight, or 0.5 parts by weight.

[0042] In the plaster provided by the present invention, the thixotropic lubricant is preferably starch ether; the preferred grade of the starch ether is CASUCOL 301, which is supplied by AVEBE of the Netherlands.

[0043] In the plaster provided by this invention, the content of the thixotropic lubricant in the dry material can be specifically 0.01 parts by weight, 0.015 parts by weight, 0.02 parts by weight, 0.025 parts by weight, 0.03 parts by weight, 0.035 parts by weight, 0.04 parts by weight, 0.045 parts by weight, 0.05 parts by weight, 0.055 parts by weight, 0.06 parts by weight, 0.065 parts by weight, 0.07 parts by weight, 0.075 parts by weight, 0.08 parts by weight, 0.085 parts by weight, 0.09 parts by weight, 0.095 parts by weight, or 0.1 parts by weight.

[0044] In the plaster provided by this invention, the tartaric acid in the setting time stabilizer is preferably L-tartaric acid; the sulfur trioxide content of the anhydrite powder is preferably not less than 48 wt%; the particle size of the anhydrite powder is preferably 1~50 μm, more preferably 1~25 μm, specifically 1 μm, 5 μm, 10 μm, 15 μm, 20 μm or 25 μm; the protein retarder is preferably Retardan 200P and / or Retardan XCP, and the above-mentioned retarders are provided by SIKA of Switzerland and SICIT 2000S.pA of Italy.

[0045] In the plastering provided by this invention, the mass ratio of tartaric acid to anhydrite powder in the setting time stabilizer can specifically be 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24, or 1:25; the mass ratio of tartaric acid to sulfate can specifically be 1:2, 1:2.5, 1: 3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5 or 1:10; the specific mass ratio of tartaric acid to protein retarder can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5.

[0046] In the plaster provided by this invention, the setting time stabilizer in the dry material can specifically be 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, 0.45 parts by weight, 0.5 parts by weight, 0.55 parts by weight, 0.6 parts by weight, 0.65 parts by weight, 0.7 parts by weight, 0.75 parts by weight, 0.8 parts by weight, 0.85 parts by weight, 0.9 parts by weight, 0.95 parts by weight, 1 part by weight, 1.05 parts by weight, 1.1 parts by weight, 1.15 parts by weight, 1.2 parts by weight, 1.25 parts by weight, 1.3 parts by weight, 1.35 parts by weight, 1.4 parts by weight, 1.45 parts by weight, or 1.5 parts by weight.

[0047] In the plaster provided by this invention, the mass ratio of dry material to water is preferably 10:(2~5), specifically 10:2, 10:2.1, 10:2.2, 10:2.3, 10:2.4, 10:2.5, 10:2.6, 10:2.7, 10:2.8, 10:2.9, 10:3, 10:3.1, 10:3.2, 10:3.3, 10:3.4, 10:3.5, 10:3.6, 10:3.7, 10:3.8, 10:3.9, 10:4, 10:4.1, 10:4.2, 10:4.3, 10:4.4, 10:4.5, 10:4.6, 10:4.7, 10:4.8, 10:4.9 or 10:5.

[0048] The present invention also provides a method for preparing the plaster described in the above technical solution, comprising the following steps:

[0049] Building gypsum powder, sand, heavy calcium carbonate powder, water-retaining agent, thixotropic lubricant and setting time stabilizer are mixed to obtain dry material;

[0050] The dry material is mixed with water to obtain plaster.

[0051] The plaster provided by this invention is neutral and has excellent environmental adaptability. More specifically, it has at least the following advantages:

[0052] 1. Construction-friendly: The dry material is neutral after being mixed with water, avoiding irritation to the skin and respiratory tract, and no special protection is required during construction.

[0053] 2. Adaptability to complex environments: It can ensure stable setting time during normal construction, and trigger a retarding compensation mechanism to suppress rapid setting when mixed with alkaline pollutants (such as cement, lime, etc.) and hydrating and hardened gypsum slurry (including dihydrate gypsum) and other fast-setting pollutants. It can ensure the normal open time of the product in scenarios where different formulas need to be switched during production and in scenarios where other materials may remain in the mixing tools at the construction site.

[0054] 3. Good environmental performance: The building gypsum powder is made of natural gypsum, which has low content of heavy metals, radioactive substances and harmful ions, and the product will not have problems such as efflorescence and peeling.

[0055] For clarity, the plastering gypsum provided by the present invention will be described in detail below through the following embodiments and comparative examples.

[0056] The raw material composition of the plaster in each embodiment and comparative example is shown in Table 1:

[0057] Table 1. Ingredients of plaster caster in the examples and comparative examples (unit: parts by weight)

[0058]

[0059] According to the formula in Table 1, pour all the dry materials into a mixer and mix them evenly. Then add water and stir thoroughly to obtain plaster.

[0060] The initial setting time test results of the plaster cast iron in each embodiment and comparative example are shown in Table 2:

[0061] Table 2. Initial setting time test results of plaster cast iron plaster in the examples and comparative examples.

[0062]

[0063] As shown in Table 2, the initial setting time of the plaster in Examples 1-3 was effectively controlled to around 2 hours. Even with external gypsum dihydrate impurities, the initial setting time still exceeded 1 hour. Furthermore, with impurities such as cement and lime, the setting time remained around 2 hours. Comparative Example 1 had a similar initial setting time to Examples 1 and 2. However, under 3‰ gypsum dihydrate contamination, the initial setting time of Comparative Example 1 drastically decreased to less than 1 hour, failing to provide normal construction open time. Under 15‰ cement and lime contamination, the setting time was also shortened to half and one-third of the original, respectively. Comparative Example 2 increased the amount of retarder, extending the initial setting time to around 200 minutes. While this improved the tolerance to contamination to some extent, the overall system was quite sensitive to the addition of gypsum dihydrate and lime. Under the experimental conditions of 3‰ gypsum dihydrate, the setting time was shortened to one-quarter of the original, and the setting time was even shorter under 15‰ lime contamination, ensuring normal construction open time in a dust-free environment. Comparative Examples 3 and 4 contained cement and lime, respectively, making them alkaline formulations with relatively high pH values ​​after mixing. Although the initial setting times of Comparative Examples 3 and 4 were longer (longer than Examples 1-3), the initial setting time rapidly decreased to less than 1 hour under external contamination with dihydrate gypsum impurities, making it impossible to guarantee normal construction open time. Although both were alkaline formulations, the setting time was also significantly shortened in the presence of external alkaline contaminants.

[0064] Based on the above test results, it can be seen that the plaster provided in this embodiment of the invention can achieve non-alkaline irritation, and can ensure stable setting time and provide sufficient workable time when there are pollution sources such as dihydrate gypsum, cement and lime.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A type of plaster, characterized in that, Includes dry materials and water; The dry material comprises, by weight parts: 30-50 parts of building plaster powder; 40-60 parts sand; 0-20 parts of heavy calcium carbonate powder; Water-retaining agent 0.1~0.5 parts; Thixotropic lubricant, 0.01~0.1 parts; Setting time stabilizer: 0.2-1.5 parts; The setting time stabilizer includes tartaric acid, anhydrite powder, sulfate and protein retarder, wherein the sulfate is aluminum sulfate and / or potassium sulfate, and the mass ratio of tartaric acid, anhydrite powder, sulfate and protein retarder is 1:(5~25):(2~10):(0.3~1.5).

2. The plastering according to claim 1, characterized in that, The building gypsum powder is natural gypsum powder; the particle size of the building gypsum powder is 50~150 mesh.

3. The plastering according to claim 1, characterized in that, The particle size of the sand is 30~200 mesh.

4. The plastering according to claim 1, characterized in that, The particle size of the heavy calcium carbonate powder is 150~350 mesh.

5. The plastering according to claim 1, characterized in that, The water-retaining agent is a cellulose ether.

6. The plastering according to claim 1, characterized in that, The thixotropic lubricant is starch ether.

7. The plastering according to claim 1, characterized in that, The tartaric acid mentioned is L-tartaric acid.

8. The plastering according to claim 1, characterized in that, The particle size of the anhydrite powder is 1~50μm.

9. The plastering according to claim 1, characterized in that, The mass ratio of the dry material to water is 10:(2~5).

10. A method for preparing plaster of any one of claims 1 to 9, characterized in that, Includes the following steps: Building gypsum powder, sand, heavy calcium carbonate powder, water-retaining agent, thixotropic lubricant and setting time stabilizer are mixed to obtain dry material; The dry material is mixed with water to obtain plaster.

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