Modified cellulose ether, lightweight plaster and preparation method thereof

Abstract

The present application relates to the technical field of plastering gypsum, and specifically discloses a modified cellulose ether, a lightweight plastering gypsum, and a preparation method thereof. The modified cellulose ether provided in the present application comprises the following components in parts by weight: 80-90 parts of cellulose ether, 5-10 parts of a dispersant, and 5-10 parts of a water reducer; the dispersant comprises polyoxyethylene distyrenated phenyl ether; further, the dispersant further comprises one or more of polyoxyethylene alkylphenol ether, sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate; the present application also provides a lightweight plastering gypsum prepared using the above-mentioned modified cellulose ether and a preparation method thereof. The modified cellulose ether provided in the present application has excellent water retention properties, can ensure the complete hydration of the plastering gypsum, and thereby improve the construction performance of the lightweight plastering gypsum.

Description

Technical Field

[0001] The present application relates to the technical field of plastering gypsum, and in particular to a modified cellulose ether, a lightweight plastering gypsum and a preparation method thereof. Background Art

[0002] Building gypsum is a low-energy cementitious material whose cementitious properties have long been recognized. With my country's growing demand for environmentally friendly materials, lightweight plaster gypsum is gaining acceptance as an interior wall leveling material. Compared to traditional cement plasters, lightweight plaster gypsum is widely used due to its light weight, good hygroscopicity, excellent volume stability, resistance to hollowing and cracking, and excellent fire resistance. Cellulose ether is a common water-retaining and thickening chemical additive in lightweight plaster gypsum, primarily serving to retain water and thicken the material.

[0003] At present, lightweight plaster gypsum made from ordinary cellulose ether still has some usage defects. For example, the water retention of lightweight plaster gypsum is poor. When it is applied to water-absorbent surfaces such as aerated concrete and porous insulation boards, the moisture in the lightweight plaster gypsum is absorbed, which affects its hydration process and ultimately makes it difficult to achieve sufficient strength, resulting in powdering, shrinkage, cracking and other phenomena.

[0004] Therefore, there is an urgent need to modify cellulose ether and give it better water retention and other properties to ensure that lightweight plaster gypsum can be completely hydrated during use, thereby eliminating the problems caused by defects such as low strength of lightweight plaster gypsum and improving the workability of plaster gypsum. Summary of the Invention

[0005] In order to improve the water retention and tensile bonding strength of natural plastering gypsum, the present application provides a modified cellulose ether, a lightweight plastering gypsum and a preparation method thereof.

[0006] In a first aspect, the present application provides a modified cellulose ether, which adopts the following technical solution:

[0007] A modified cellulose ether comprises the following components in parts by weight: 80-90 parts of cellulose ether, 5-10 parts of a dispersant, and 5-10 parts of a water reducer; the dispersant comprises polyoxyethylene distyrenated phenyl ether.

[0008] The present application utilizes polyoxyethylene distyrenated phenyl ether to modify cellulose ether, thereby obtaining a modified cellulose ether having excellent water retention, thickening and bonding properties. When added to lightweight plaster gypsum, it can significantly improve the water retention of the lightweight plaster gypsum, allowing it to be fully hydrated during use, ultimately achieving sufficient construction strength. Polyoxyethylene distyrenated phenyl ether, as a dispersant, is commonly used to improve the wettability and permeability of a system. The inventors of the present application have discovered that polyoxyethylene distyrenated phenyl ether can improve the solubility of each component in the lightweight plaster gypsum in water, effectively avoiding the phenomenon of cellulose ether agglomeration or the formation of small micelles in other component materials, thereby reducing the amount of water used when mixing the lightweight plaster gypsum and improving the strength of the lightweight plaster gypsum.

[0009] In this application, polyoxyethylene distyrenated phenyl ether can ionize electrolytes in water, increasing the internal ion concentration of the system. This in turn creates a concentration difference between the polymer interior and the external solution, leading to reverse osmosis. Free water enters the polymer interior in large quantities, thereby achieving a water-retention effect. Cellulose ether exhibits a three-dimensional network structure in water and possesses inherent elasticity, allowing it to encapsulate numerous water molecules, forming a gel-like state on the exterior of the molecular chain.

[0010] Preferably, the dispersant further comprises one or more of polyoxyethylene alkylphenol ether, sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate.

[0011] In a specific embodiment, the dispersant can be polyoxyethylene distyrenated phenyl ether, a mixture of polyoxyethylene distyrenated phenyl ether and sodium tripolyphosphate, a mixture of polyoxyethylene distyrenated phenyl ether and sodium hexametaphosphate, or a mixture of polyoxyethylene distyrenated phenyl ether, polyoxyethylene alkylphenol ether and sodium hexametaphosphate.

[0012] Preferably, the dispersant is a mixture of polyoxyethylene distyrenated phenyl ether and sodium tripolyphosphate; the weight ratio of the polyoxyethylene distyrenated phenyl ether to the sodium tripolyphosphate is 1:(0.25-0.65).

[0013] Through experimental research, the present application found that when a mixture of polyoxyethylene distyrenated phenyl ether and sodium tripolyphosphate is used as a dispersant and the weight ratio of the two is further controlled within the above range, the resulting modified cellulose ether has better water retention and adhesion. When used in lightweight plaster gypsum, it can not only reduce the amount of water used during mixing, but also improve the strength of the lightweight plaster gypsum, thereby achieving excellent construction effects.

[0014] In some embodiments, the weight ratio of the polyoxyethylene distyrenated phenyl ether to the sodium tripolyphosphate may be 1:(0.25-0.4) or 1:(0.4-0.65).

[0015] In a specific embodiment, the weight ratio of the polyoxyethylene distyrenated phenyl ether to the sodium tripolyphosphate can also be 1:0.25, 1:0.4 or 1:0.65.

[0016] Preferably, the cellulose ether is hydroxypropyl methylcellulose ether, and the water reducer is a polycarboxylate water reducer.

[0017] In the present application, hydroxypropyl methylcellulose ether is a high molecular polymer with a three-dimensional network structure. There are many hydrophilic groups such as carboxyl, hydroxyl, phthalamide and ether groups distributed on its molecular chain. When it is dissolved in water, the hydrophilic groups will combine with water molecules to form hydrogen bonds, absorb a large amount of water by chemical adsorption, and then present a gel state. Polycarboxylic acid water reducer is a high-performance water reducer with a "comb-like" molecular structure. A plurality of side chains with a certain length and rigidity are connected to its main molecular chain. Sulfonate or other groups are present on the main chain molecules, which can be uniformly adsorbed on the surface of gypsum particles, thereby reducing the agglomeration between gypsum material particles. At the same time, the branched chain molecules and the branched chain molecules on the surface of other gypsum particles will form a three-dimensional intersection, hindering the mutual approach between gypsum particles, thereby achieving the effect of water reduction through dispersion, and then improving the strength of lightweight plaster gypsum and improving the construction performance of lightweight plaster gypsum.

[0018] Preferably, the viscosity of the hydroxypropyl methylcellulose ether is 100,000-150,000 mPa·s.

[0019] In this application, the higher the viscosity of the hydroxypropyl methylcellulose ether, the stronger its water retention performance; however, when the viscosity of the hydroxypropyl methylcellulose ether is too high, the water requirement of the lightweight plaster gypsum increases, resulting in a decrease in the strength of the lightweight plaster gypsum; when the viscosity of the hydroxypropyl methylcellulose ether is too low, the water retention performance of the lightweight plaster gypsum is poor, which easily causes water loss, and further leads to a low strength of the lightweight plaster gypsum. Therefore, in order to ensure that the lightweight plaster gypsum has sufficient water retention, strength, and good workability, this application controls the viscosity of the hydroxypropyl methylcellulose ether within the above range to achieve the best construction effect.

[0020] In some embodiments, the viscosity of the hydroxypropyl methylcellulose ether may be 100,000-120,000 mPa·s or 120,000-150,000 mPa·s.

[0021] In some specific embodiments, the viscosity of the hydroxypropyl methylcellulose ether may also be 100,000 mPa·s, 120,000 mPa·s or 150,000 mPa·s.

[0022] In a second aspect, the present application provides a lightweight plastering gypsum, which adopts the following technical solution:

[0023] A lightweight plaster comprises the modified cellulose ether.

[0024] Preferably, the lightweight plaster gypsum comprises the following components in parts by weight: 650-900 parts of gypsum powder, 50-100 parts of vitrified microspheres, 50-100 parts of heavy calcium powder, 1.5-3 parts of modified cellulose ether, and 1-3 parts of retarder.

[0025] The present application provides a lightweight plaster made from modified cellulose ether. The lightweight plaster has good water retention, requires less water during mixing, has good strength, and excellent construction performance, and has a good prospect for use.

[0026] In some embodiments, the weight portion of the modified cellulose ether may be 1.5-2 parts, 1.5-2.5 parts, 1.5-3 parts, 2-2.5 parts, 2-3 parts, or 2.5-3 parts.

[0027] In a specific embodiment, the weight portion of the modified cellulose ether may also be 1.5 parts, 2 parts, 2.5 parts or 3 parts.

[0028] Preferably, the lightweight plaster gypsum comprises the following components in parts by weight: 650-900 parts of gypsum powder, 50-100 parts of vitrified microspheres, 50-100 parts of heavy calcium powder, 1.5-2.5 parts of modified cellulose ether, and 1-3 parts of retarder.

[0029] The present application further controls the addition amount of the modified cellulose ether within the above range, and the obtained lightweight plastering gypsum has better comprehensive performance of water retention and strength, and better construction effect.

[0030] Preferably, the water retention rate of the lightweight plaster is 80-92%, and the tensile bond strength is 0.80-1.04 MPa.

[0031] In a third aspect, the present application provides a method for preparing lightweight plaster gypsum.

[0032] A method for preparing a lightweight plastering gypsum comprises the following steps:

[0033] Preparation of modified cellulose ether: uniformly mixing cellulose ether, dispersant and water reducing agent to obtain modified cellulose ether;

[0034] Preparation of lightweight plaster gypsum: first, the modified cellulose ether is mixed with a retarder to obtain a mixture A; then, the mixture A, gypsum powder and heavy calcium powder are mixed to obtain a mixture B; finally, vitrified microspheres are added to the above mixture B and stirred evenly to obtain the lightweight plaster gypsum.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. The present application utilizes one or more dispersants comprising polyoxyethylene distyrenated phenyl ether to modify cellulose ether. The obtained cellulose ether can improve the solubility of each component in lightweight plaster gypsum in water, effectively avoiding the phenomenon of cellulose ether agglomeration or the formation of small micelles in other component materials, thereby reducing the amount of water used in mixing lightweight plaster gypsum and improving the strength of lightweight plaster gypsum.

[0037] 2. This application uses a mixture of polyoxyethylene distyrenated phenyl ether and sodium tripolyphosphate in a weight ratio of 1: (0.25-0.65) as a dispersant, and further controls the weight ratio of the two within the above range. The resulting modified cellulose ether has better water retention and adhesion. When used in lightweight plaster gypsum, it can not only reduce the amount of water used during mixing, but also improve the strength of the lightweight plaster gypsum, thereby achieving excellent construction results.

[0038] 3. This application uses hydroxypropyl methylcellulose ether with a viscosity range of 100,000-150,000 mPa·s, which can ensure that the lightweight plaster gypsum requires less mixing water, has good water retention, and has excellent strength after drying.

[0039] 4. The lightweight plastering gypsum prepared using modified cellulose ether in this application has a water retention rate of 80-92% and a tensile bond strength of 0.80-1.04 MPa. It has good water retention, requires less water during mixing, has good strength, and has excellent construction performance, and has a good prospect for use. DETAILED DESCRIPTION

[0040] The present application provides a modified cellulose ether comprising the following components in parts by weight: 80-90 parts cellulose ether, 5-10 parts dispersant, and 5-10 parts water reducer. The dispersant comprises polyoxyethylene distyrenated phenyl ether. Furthermore, the dispersant further comprises one or more of polyoxyethylene alkylphenol ether, sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate. Furthermore, the dispersant is a mixture of polyoxyethylene distyrenated phenyl ether and sodium tripolyphosphate; the weight ratio of the polyoxyethylene distyrenated phenyl ether to the sodium tripolyphosphate is 1:(0.25-0.65).

[0041] Wherein, the cellulose ether is hydroxypropyl methylcellulose ether, the water reducer is a polycarboxylic acid water reducer; and the viscosity of the hydroxypropyl methylcellulose ether is 100,000-150,000 mPa·s.

[0042] The present application provides a lightweight plastering plaster comprising the following components in parts by weight: 650-900 parts of gypsum powder, 50-100 parts of vitrified microspheres, 50-100 parts of heavy calcium powder, 1.5-3 parts of modified cellulose ether, and 1-3 parts of a retarder. Furthermore, the lightweight plastering plaster comprises the following components in parts by weight: 650-900 parts of gypsum powder, 50-100 parts of vitrified microspheres, 50-100 parts of heavy calcium powder, 1.5-2.5 parts of modified cellulose ether, and 1-3 parts of a retarder.

[0043] The preparation method of the above-mentioned lightweight plastering gypsum comprises the following steps:

[0044] (1) Preparation of modified cellulose ether: uniformly mixing cellulose ether, dispersant, and water reducer to obtain modified cellulose ether;

[0045] (2) Preparation of lightweight plaster stone: first, the modified cellulose ether is mixed with the retarder to obtain mixture A; then, mixture A, gypsum powder and heavy calcium powder are mixed to obtain mixture B; finally, vitrified microspheres are added to the above mixture B and stirred evenly to obtain lightweight plaster gypsum.

[0046] In the present application, the CAS number of hydroxypropyl methylcellulose ether is 9004-65-3; the model of polyoxyethylene distyrenated phenyl ether is EMULGEN A-60, purchased from Xingtianwai Chemical (Shanghai) Co., Ltd.; the model of polycarboxylic acid water reducer is CP1801X, purchased from Nanjing Xinyi Synthetic Technology Co., Ltd.; gypsum powder is purchased from Beijing Shanshui Wenyuan New Building Materials Co., Ltd.; vitrified microspheres are purchased from Xinyang Pingqiao District Yanxu Insulation Materials Factory; heavy calcium powder is purchased from Shijiazhuang Weijia Mineral Products Co., Ltd.; the retarder is a gypsum retarder, purchased from Jinan Qianqi Chemical Co., Ltd.; the remaining raw materials and reagents can also be obtained through commercial purchase.

[0047] The present application is further described in detail below with reference to preparation examples, embodiments and performance testing experiments.

[0048] Preparation Examples 1-7

[0049] Preparation Examples 1-7 respectively provide a modified cellulose ether, the difference being the weight ratio of each component in the dispersant of the modified cellulose ether.

[0050] The modified cellulose ether is prepared by uniformly mixing 85 g of hydroxypropyl methylcellulose ether with a viscosity of 100,000 mPa·s, 5 g of a dispersant, and 10 g of a polycarboxylate water-reducing agent to obtain the modified cellulose ether.

[0051] Table 1 Weight ratio of each component in the dispersant in the modified cellulose ether provided in Preparation Example 1-1

[0052]

[0053] Preparation Example 8

[0054] Preparation Example 8 was prepared according to the method of Preparation Example 3, except that the viscosity of hydroxypropyl methylcellulose ether was 120,000 mPa·s.

[0055] Preparation Example 9

[0056] Preparation Example 9 was carried out according to the method of Preparation Example 3, except that the viscosity of hydroxypropyl methylcellulose ether was 150,000 mPa·s.

[0057] Comparative Preparation Examples 1-3

[0058] Comparative Preparation Examples 1-3 were prepared according to the method of Preparation Example 3, except that the type of dispersant in the modified cellulose ether was as shown in Table 2.

[0059] Table 2 Types of dispersants in the modified cellulose ethers provided in Comparative Preparation Examples 1-3

[0060]

[0061] Comparative Preparation Example 4

[0062] Comparative Preparation Example 4 was carried out according to the method of Preparation Example 3, except that the viscosity of the hydroxypropyl methylcellulose ether was 50,000 mPa·s.

[0063] Comparative Preparation Example 5

[0064] Comparative Preparation Example 5 was prepared according to the method of Preparation Example 3, except that the viscosity of the hydroxypropyl methylcellulose ether was 200,000 mPa·s.

[0065] Examples 1-9

[0066] Examples 1-9 provide a lightweight plaster, respectively. The difference is that the modified cellulose ether in the lightweight plaster is derived from Preparation Examples 1-9, respectively.

[0067] The lightweight plaster gypsum is prepared as follows: first, 1.5 g of modified cellulose ether is mixed with 2 g of gypsum retarder to obtain mixture A; then, mixture A, 800 g of gypsum powder and 100 g of heavy calcium powder are mixed to obtain mixture B; finally, 95 g of vitrified microspheres are added to mixture B and stirred evenly to obtain the lightweight plaster gypsum.

[0068] Examples 10-12

[0069] Examples 10-12 were carried out according to the method of Example 8, except that the amount of modified cellulose ether added to the lightweight plaster was changed.

[0070] Table 3 Addition amount of each component in the lightweight plaster of Examples 10-12

[0071]

[0072] Comparative Examples 1-5

[0073] Comparative Examples 1-5 were prepared according to the method of Example 3, except that the modified cellulose ether in the lightweight plastering gypsum was derived from Comparative Preparation Examples 1-5, respectively.

[0074] Comparative Example 6

[0075] Comparative Example 6 was carried out according to the method of Example 8, except that the amount of modified cellulose ether added to the lightweight plaster was 1 g.

[0076] Comparative Example 7

[0077] Comparative Example 7 was carried out according to the method of Example 8, except that the amount of modified cellulose ether added to the lightweight plaster was 4 g.

[0078] Performance testing

[0079] According to the test method in GB / T 28627-2012 "Plastering Gypsum", the standard diffusion water consumption, water retention rate, bulk density, flexural strength, compressive strength and tensile bond strength of the lightweight plastering gypsum provided in the examples and comparative examples were tested, and the results are shown in Table 4.

[0080] After testing, the bulk density of the lightweight plaster provided by Examples 1-12 and Comparative Examples 1-7 is less than 1000 g / cm 3 , in line with the standard requirements of "Plastering Gypsum".

[0081] Table 4 Performance test results of lightweight plaster provided by Examples and Comparative Examples

[0082]

[0083] The present application provides a lightweight plastering gypsum, the standard diffusion water consumption of the lightweight plastering gypsum is 54-58%, the water retention rate is greater than 75%, the flexural strength is greater than or equal to 1.5 MPa, the compressive strength is greater than or equal to 2.9 MPa, and the tensile bonding strength is greater than or equal to 0.75 MPa. This indicates that the lightweight plastering gypsum provided in the present application requires little water for mixing, has excellent water retention and strength, and can meet higher construction requirements.

[0084] According to the test results of Examples 1-7 and Comparative Examples 1-3, the water retention rate of the lightweight plaster gypsum obtained in Examples 1-7 is greater than 75%, and the tensile bond strength is greater than 0.75 MPa; the water retention rate of the lightweight plaster gypsum obtained in Comparative Examples 1-3 is less than 75%, and the tensile bond strength is less than 0.7 MPa, indicating that the present application uses a dispersant containing polyoxyethylene distyrenated phenyl ether to modify cellulose ether, and the obtained modified cellulose ether can improve the water retention and tensile bond strength of the lightweight plaster gypsum, thereby improving the construction performance of the lightweight plaster gypsum.

[0085] Further comparison of Examples 1-7 revealed that the water retention rate of the lightweight plaster obtained in Examples 2-4 was greater than 80%, the flexural strength was greater than 1.5 MPa, the compressive strength was greater than 3.0 MPa, and the tensile bond strength was greater than 0.85 MPa, indicating that the lightweight plaster obtained in this application, which was modified by a mixture of polyoxyethylene distyrenated phenyl ether and sodium tripolyphosphate in a weight ratio of 1: (0.25-0.65), had better construction performance.

[0086] According to the test results of Example 3, Examples 8-9, and Comparative Examples 4-5, the water retention rate of the lightweight plaster gypsum obtained in Examples 3 and 8-9 is 89-92%, the flexural strength is 1.9-2.2 MPa, the compressive strength is 3.2-3.6 MPa, and the tensile bond strength is 0.87-1.04 MPa; the water retention rate of the lightweight plaster gypsum obtained in Comparative Example 4 is only 65%; the standard diffusion water consumption of the lightweight plaster gypsum obtained in Comparative Example 5 is as high as 65%, and the tensile bond strength is only 0.48 MPa, indicating that the present application adopts hydroxypropyl methylcellulose ether with a viscosity of 100,000-150,000 mPa·s, which can reduce the water consumption during mixing of the lightweight plaster gypsum and improve the strength of the lightweight plaster gypsum while ensuring the water retention of the lightweight plaster gypsum.

[0087] According to the test results of Example 3, Examples 10-12, and Comparative Examples 6-7, the standard diffusivity water consumption of the lightweight plastering gypsum obtained in Examples 3 and 10-12 was 54-58%, the water retention rate was 91-94%, the flexural strength was 1.8-2.2 MPa, the compressive strength was 3.1-3.5 MPa, and the tensile bond strength was 0.84-0.95 MPa; the water retention rate of the lightweight plastering gypsum obtained in Comparative Example 6 was only 72%, and the tensile bond strength was only 0.63 MPa, which did not meet the construction requirements; the standard diffusivity water consumption of the lightweight plastering gypsum obtained in Comparative Example 7 was 63%, and the tensile bond strength was only 0.55 MPa, which did not meet the construction requirements. Therefore, it is shown that the present application can obtain a lightweight plastering gypsum with excellent performance by controlling the addition amount of modified cellulose ether between 1.5 and 3 parts.

[0088] In summary, the present application uses a dispersant containing polyoxyethylene distyrenated phenyl ether to modify cellulose ether, and controls the addition amount of modified cellulose ether to be between 1.5-3 parts, thereby obtaining a lightweight plaster with excellent water retention, low mixing water consumption and high strength.

[0089] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A modified cellulose ether, characterized in that The method comprises the following components in parts by weight: 80-90 parts of cellulose ether, 5-10 parts of dispersant, and 5-10 parts of water reducing agent; The dispersant is a mixture of polyoxyethylene distyrenated phenyl ether and sodium tripolyphosphate; the weight ratio of the polyoxyethylene distyrenated phenyl ether to the sodium tripolyphosphate is 1:(0.25-0.65).

2. The modified cellulose ether according to claim 1, characterized in that The cellulose ether is hydroxypropyl methylcellulose ether, and the water reducer is a polycarboxylic acid water reducer.

3. The modified cellulose ether according to claim 2, characterized in that The viscosity of the hydroxypropyl methylcellulose ether is 100,000-150,000 mPa·s.

4. A lightweight plastering gypsum, characterized in that: The invention comprises the modified cellulose ether according to any one of claims 1 to 3.

5. The lightweight plaster according to claim 4, characterized in that The lightweight plaster gypsum comprises the following components in parts by weight: 650-900 parts of gypsum powder, 50-100 parts of vitrified microspheres, 50-100 parts of heavy calcium powder, 1.5-3 parts of modified cellulose ether, and 1-3 parts of retarder.

6. The lightweight plaster according to claim 4, characterized in that The lightweight plaster gypsum comprises the following components in parts by weight: 650-900 parts of gypsum powder, 50-100 parts of vitrified microspheres, 50-100 parts of heavy calcium powder, 1.5-2.5 parts of modified cellulose ether, and 1-3 parts of retarder.

7. The lightweight plaster according to any one of claims 4 to 6, characterized in that The lightweight plaster has a water retention rate of 80-92% and a tensile bonding strength of 0.80-1.04 MPa.

8. The method for preparing the lightweight plaster according to any one of claims 4 to 6, characterized in that: The following steps are involved: Preparation of modified cellulose ether: uniformly mixing cellulose ether, dispersant and water reducing agent to obtain modified cellulose ether; Preparation of lightweight plaster gypsum: first, the modified cellulose ether is mixed with a retarder to obtain a mixture A; then, the mixture A, gypsum powder and heavy calcium powder are mixed to obtain a mixture B; finally, vitrified microspheres are added to the above mixture B and stirred evenly to obtain the lightweight plaster gypsum.

Images