A novel cellulose ether and a method for producing the same
By preparing novel cellulose ethers and using compounding agents such as retarders and air-entraining agents to control calcium ion crosslinking, the post-thickening problem of phosphogypsum mortar can be solved, achieving a balance between workability and mechanical properties, and reducing production costs and energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING PENGKAI FINE CHEM CO LTD
- Filing Date
- 2026-03-12
- Publication Date
- 2026-06-02
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention belongs to the field of building materials technology, and more specifically, relates to a novel cellulose ether and its preparation method. Background Technology
[0002] Cellulose ethers are indispensable water-retaining and thickening agents in gypsum-based mortars. However, when using phosphogypsum, an industrial byproduct of gypsum, as a cementitious material in mortar, the addition of traditional cellulose ethers to phosphogypsum mortar encounters a serious "post-thickening" problem. Phosphogypsum contains various soluble impurities, such as residual phosphoric acid, fluorides, sodium salts, potassium salts, and organic matter. In particular, anions such as phosphate combine with calcium ions in the slurry, forming "calcium bridge" cross-linking structures between cellulose ether molecular chains, or directly adsorbing onto the cellulose ether chains. This causes the molecular chains to curl up and entangle with each other, macroscopically manifesting as a continuous increase in mortar consistency and a rapid loss of fluidity after mixing. This results in a significant increase in consistency and a sharp loss of fluidity in the mortar for a period of time after mixing (usually within 30 minutes to 2 hours). This phenomenon is called "post-thickening" or "residual thickening."
[0003] Post-thickening causes significant problems during construction: it makes mortar pumping difficult, reduces its smoothness during application, and makes plastering laborious. In severe cases, it can even cause the mortar to solidify in the container (losing workability, i.e., a pseudo-set state), rendering it unusable. This not only affects construction efficiency and quality but also results in material waste. Currently, the industry typically uses processes such as water washing and lime neutralization to pre-treat phosphogypsum to reduce impurity content, but this greatly increases production costs and energy consumption. Some studies have attempted to alleviate post-thickening by compounding retarders or water-reducing agents, but the effects are limited and may negatively impact the final strength of the mortar.
[0004] Therefore, in view of this, we will study and improve the existing structure and its deficiencies, and provide a new type of cellulose ether and its preparation method, in order to achieve a more practical value. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a novel cellulose ether and its preparation method.
[0006] The purpose and efficacy of this invention, which describes a novel cellulose ether and its preparation method, are achieved through the following specific technical means: A novel cellulose ether comprises hydroxypropyl methylcellulose (HPMC) prepared by reacting cellulose, liquid alkali, chloromethane, and propylene oxide in a molar ratio of 1:2~5:1~3:0.2~0.8, a retarder, a dispersant, a water-reducing agent, an air-entraining agent, and a starch ether; wherein the mass ratio of HPMC, retarder, dispersant, water-reducing agent, air-entraining agent, and starch ether is 1:(0.01~0.08):(0.01~0.06):(0.02:0.08):(0.01~0.03):(0.08:0.15).
[0007] Furthermore, the water-reducing agent includes one or more of sodium tripolyphosphate (STPP), industrial-grade polycarboxylate superplasticizer powder (PC), or powdered sulfonated melamine superplasticizer.
[0008] Furthermore, retarders include one or more of phosphates, sugars, and lignin sulfonic acid.
[0009] Furthermore, the dispersant includes one or more of sodium polyacrylate, sodium polycarboxylate, sodium tripolyphosphate, and sodium pyrophosphate.
[0010] Furthermore, the air-entraining agent includes one or more of rosin-based air-entraining agents, alkylbenzene sulfonates, and protein-based air-entraining agents.
[0011] Furthermore, the starch ether includes one or more of cationic starch ether, anionic starch ether, hydroxypropyl starch ether, and hydroxyethyl starch ether.
[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. This method not only solves the core problem of post-thickening but also takes into account other key properties of phosphogypsum mortar. The compounded retarder provides a moderate retarding effect while blocking calcium ions, avoiding the problem of excessively prolonging the setting time by simply addressing consistency. The introduced microbubbles improve the workability without significantly negatively impacting the final strength, achieving a perfect balance between workability and mechanical properties.
[0013] 2. This invention eliminates the complex steps of synthesis, washing and purification, and mainly relies on efficient mechanical mixing equipment, which greatly simplifies the production process, shortens the production cycle and significantly reduces energy consumption. Detailed Implementation
[0014] The embodiments of the present invention will be described in further detail below with reference to examples. These examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.
[0015] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0016] Example 1
[0017] This invention provides a novel method for preparing cellulose ethers, comprising the following steps: 1. Raw material preparation and feeding: The reactants are cellulose, liquid alkali, chloromethane, and propylene oxide, with a molar ratio of 1:2.25:2.14:0.45.
[0018] 2. Special etherification process: In a closed reactor, the temperature is gradually increased to the etherification reaction temperature of 58-105℃. The etherification reaction is carried out at this temperature for 90-240 min. The pressure is maintained at 0.9-2.3 MPa during the reaction to prepare a medium-low viscosity hydroxypropyl methylcellulose ether slurry.
[0019] 3. Special washing and granulation treatment: The crude product after etherification is added to a centrifugal washing device and hot water at 80-95℃ is used to remove salt under high-speed centrifugal washing. Subsequently, the density is improved by freezing water at -10℃~0℃, so that the product reaches a suitable bulk density.
[0020] 4. Drying and pulverizing: The intermediate product after granulation is dried in an airflow drying tower at 105-120℃. The dried product is then sieved through an 80-120 mesh sieve to obtain high gel temperature and low ash hydroxypropyl methylcellulose.
[0021] 5. Physical Mixing: The prepared HPMC pure product was physically dry-mixed with retarder (sodium hexametaphosphate), dispersant (BASF WA3710 F), water-reducing agent (BASF F-10), air-entraining agent (sodium α-alkenyl sulfonate), and starch ether (YT-10 hydroxypropyl starch ether) in a specific ratio of 1:(0.04):(0.05):(0.03):(0.02):(0.12). Using an airflow mixing device, at room temperature and pressure, the HPMC pure product and each additive were added to the mixer. The mixing speed and time were controlled, and the mixture was mixed three times. The first time, the pressure was 1.0~1.4 MPa, with a 5-minute interval. The pressure of the last two times was greater than 1.0 MPa, ensuring thorough and uniform physical mixing to obtain modified cellulose ether A.
[0022] Example 2
[0023] The preparation steps in this embodiment are the same as in Example 1; however, the difference lies in the following: the HPMC pure product prepared above is physically dry-mixed with retarder, dispersant, water-reducing agent, air-entraining agent, and starch ether (specific components as above) in a specific ratio of 1:(0.03):(0.6):(0.06):(0.02):(0.10). Using an airflow mixing device, at room temperature and pressure, the HPMC pure product and each additive are added to the mixer. The mixing speed and time are controlled, and the mixture is mixed three times. The first time, the pressure is 1.0~1.4 MPa, with a 5-minute interval. The pressure for the next two times is greater than 1.0 MPa, ensuring thorough and uniform physical mixing to obtain modified cellulose ether B.
[0024] Example 3
[0025] The steps are the same as in Example 1, but the difference between Example 3 and Example 1 is that the HPMC pure product prepared above is physically dry-mixed with retarder, dispersant, water-reducing agent, air-entraining agent, and starch ether (specific components as above) in a specific ratio of 1:(0.04):(0.05):(0.04):(0.03):(0.10). Using an airflow mixing device, at room temperature and pressure, the HPMC pure product and each additive are added to the mixer. The mixing speed and time are controlled, and the mixture is mixed three times. The first time, the pressure is 1.0~1.4 MPa, with a 5-minute interval. The pressure of the last two times is greater than 1.0 MPa, ensuring thorough and uniform physical mixing to obtain modified cellulose ether C.
[0026] Example 4
[0027] The steps are the same as in Example 1, but the difference between Example 4 and Example 1 is that the HPMC pure product prepared above is physically dry-mixed with retarder, dispersant, water-reducing agent, air-entraining agent, and starch ether (specific components as above) in a specific ratio of 1:(0.06):(0.05):(0.06):(0.03):(0.10). Using an airflow mixing device, at room temperature and pressure, the HPMC pure product and each additive are added to the mixer. The mixing speed and time are controlled, and the mixture is mixed three times. The first time, the pressure is 1.0~1.4 MPa, with a 5-minute interval. The pressure of the last two times is greater than 1.0 MPa, ensuring thorough and uniform physical mixing to obtain modified cellulose ether D.
[0028] Example 5
[0029] The steps are the same as in Example 1, but the difference between Example 5 and Example 1 is that the HPMC pure product prepared above is physically dry-mixed with retarder, dispersant, water-reducing agent, air-entraining agent, and starch ether (specific components as above) in a specific ratio of 1:(0.08):(0.05):(0.08):(0.03):(0.08). Using an airflow mixing device, at room temperature and pressure, the HPMC pure product and each additive are added to the mixer. The mixing speed and time are controlled, and the mixture is mixed three times. The first time, the pressure is 1.0~1.4 MPa, with an interval of 5 minutes. The pressure of the last two times is greater than 1.0 MPa, ensuring thorough and uniform physical mixing to obtain modified cellulose ether E.
[0030] Comparative Example: The difference from Example 1 is that commercially available ordinary hydroxypropyl methylcellulose ether (HPMC) with the same viscosity grade was used.
[0031] Performance testing: 1. Mortar formula: 800g phosphogypsum powder (unpurified), 100g heavy calcium carbonate powder, 100g quartz sand, 40g vitrified microspheres, 2.5g of the prepared modified cellulose ether (or control sample HPMC), and 580g water.
[0032] 2. Test Method: The initial flowability of the mortar, and the flowability after standing for 30 minutes and 45 minutes, are tested according to GB / T 2419-2005 "Determination of Flowability of Cement Mortar". The flowability loss rate is calculated.
[0033] The test results are shown in the table below:
[0034] Conclusion: The test results show that the phosphogypsum plastering mortar with modified cellulose ether prepared by the present invention has a much smaller loss of fluidity over time than the phosphogypsum mortar using ordinary HPMC, effectively suppressing the post-thickening phenomenon, which proves the significant effect of the present invention.
[0035] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.
Claims
1. A novel cellulose ether, characterized in that: It includes 71.43%~88.50% hydroxypropyl methylcellulose, 0.71%~7.08% retarder, 0.71%~7.08% dispersant, 0.71%~5.31% water-reducing agent, 1.43%~7.08% air-entraining agent, and 5.71%~13.27% starch ether; and hydroxypropyl methylcellulose is obtained by reacting cellulose, liquid alkali, chloromethane, and propylene oxide, with a molar ratio of 1:2.25:2.14:0.
45.
2. The novel cellulose ether as described in claim 1, characterized in that: The water-reducing agent includes one or more of sodium tripolyphosphate (STPP), industrial-grade polycarboxylate superplasticizer powder (PC), or powdered sulfonated melamine superplasticizer.
3. The novel cellulose ether as described in claim 1, characterized in that: The retarder includes one or more of phosphates, sugars, and lignin sulfonic acid.
4. The novel cellulose ether as described in claim 1, characterized in that: The dispersant includes one or more of sodium polyacrylate, sodium polycarboxylate, sodium tripolyphosphate, and sodium pyrophosphate.
5. A novel cellulose ether as described in claim 1, characterized in that: The air-entraining agent includes one or more of rosin-based air-entraining agents, alkylbenzene sulfonates, and protein-based air-entraining agents.
6. The novel cellulose ether as described in claim 1, characterized in that: The starch ether includes one or more of cationic starch ether, anionic starch ether, hydroxypropyl starch ether, and hydroxyethyl starch ether.
7. The method for preparing the novel cellulose ether as described in claim 1, characterized in that: Includes the following steps: S1; Cellulose, liquid alkali, chloromethane, and propylene oxide are gradually heated in a reactor according to the above molar ratio to etherification reaction. The temperature is 58~105℃, the reaction time is 90-240min, and the reaction pressure is maintained at 0.9-2.3MPa to obtain medium and low viscosity hydroxypropyl methylcellulose ether slurry. S2; The crude etherified product is added to a centrifugal washing device, and salt is removed by using hot water at 80-95℃ and high-speed centrifugal washing. Subsequently, the density is improved by using -10~0℃ chilled water to make the product reach a suitable bulk density. S3; The intermediate product in step S2 is dried in an airflow drying tower at 105-120℃, and the dried product is sieved through an 80-120 mesh sieve to obtain high gel temperature, low ash hydroxypropyl methylcellulose. S4; The hydroxypropyl methylcellulose from step S3 is physically dry-mixed with the retarder, dispersant, water-reducing agent, air-entraining agent, and starch ether in a specific ratio of 1:(0.01~0.08):(0.01~0.06):(0.02~0.08):(0.01~0.03):(0.08~0.15). Using an airflow mixing device, at room temperature and pressure, the pure HPMC and all additives are added to the mixer. The mixing speed and time are controlled, and the mixture is mixed three times. The first time, the pressure is 1.0~1.4 MPa, with a 5-minute interval. The pressure for the next two times is greater than 1.0 MPa, ensuring thorough and uniform physical mixing.