Gypsum buffering retarder and method for preparing the same

Abstract

The present application relates to a kind of gypsum buffering retarder and its preparation method, using sucrose as barrier agent, with coagulant and organic acid and its soluble salt class retarder, protein and its derivative class retarder together preparation gypsum buffering retarder.Sucrose is ball milled with coagulant, and coagulant can provide more crystal nucleus, improve hydration speed and coagulation efficiency;Sucrose as barrier agent, its surface has very strong polarity, and is ball milled with coagulant, it can be wrapped in the surface of coagulant, can block the effect of coagulant in early stage.Gypsum buffering retarder in gypsum mortar before the operable time, the retardation of organic acid and its soluble salt class retarder and protein and its derivative class retarder is dominant, after the operable time, the coagulation of coagulant is dominant.During the setting process of gypsum mortar, sucrose, coagulant, organic acid and its soluble salt class retarder and protein and its derivative class retarder jointly act, can reduce the fluctuation of gypsum mortar product setting time caused by the fluctuation of gypsum raw material setting time.

Description

Technical Field

[0001] This invention relates to the field of gypsum mortar additives, and more particularly to a gypsum buffer retarder and its preparation method. Background Technology

[0002] With the emergence of the trend of "fully furnished" delivery of commercial and residential properties, gypsum mortar products, characterized by short setting time, low shrinkage, high strength, short curing period, lightweight, fire resistance, sound insulation, heat insulation, and humidity regulation, are increasingly becoming an important material, leading to a significant increase in demand. According to industry statistics, the total national output of gypsum mortar in 2021 was approximately 12 million tons, and each ton of gypsum mortar requires approximately 0.5 kg of retarder, resulting in a demand of approximately 6,000 tons of gypsum retarder.

[0003] Commonly used gypsum retarder agents mainly fall into three categories: organic acids and their soluble salts, alkaline phosphates, and protein-based retarder agents. When used, these three types of retarder agents exhibit large fluctuations in setting time, long intervals between open and final setting times, significant strength loss, poor stability, and poor compatibility. In production and use, gypsum mortar products are prone to problems such as prolonged non-setting, powdering, cracking, and poor stability, resulting in low pass rates, frequent rework, and constant customer complaints. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a gypsum buffer retarder and its preparation method. Sucrose is used as a barrier agent, and the gypsum buffer retarder is produced by ball milling and mixing with a setting accelerator, organic acids and their soluble salts as retarders, and proteins and their derivatives as retarders in a specific ratio. This invention solves the problems of large fluctuations in setting time, long intervals between open and final setting times, significant strength loss, poor stability, and poor compatibility of traditional retarders.

[0005] To solve the above problems, the present invention is achieved through the following technical solution:

[0006] The first objective of this invention is:

[0007] A gypsum buffer retarder is provided, comprising the following components in parts by weight:

[0008]

[0009] Another preferred embodiment of the gypsum buffer retarder of the present invention is:

[0010] The gypsum buffer retarder comprises the following components in parts by weight:

[0011]

[0012] Another preferred embodiment of the gypsum buffer retarder of the present invention is:

[0013] The gypsum buffer retarder comprises the following components in parts by weight:

[0014]

[0015] Another preferred embodiment of the gypsum buffer retarder of the present invention is:

[0016] The gypsum buffer retarder comprises the following components in parts by weight:

[0017]

[0018] Another preferred embodiment of the gypsum buffer retarder of the present invention is:

[0019] The coagulant is gypsum, an industrial byproduct of solid waste.

[0020] Another preferred embodiment of the gypsum buffer retarder of the present invention is:

[0021] The coagulant is one or a mixture of several of the following: natural dihydrate gypsum, desulfurized dihydrate gypsum, phosphate dihydrate gypsum, and potassium sulfate.

[0022] Another preferred embodiment of the gypsum buffer retarder of the present invention is:

[0023] The organic acid and its soluble salt retarder are one or a mixture of several of citric acid, sodium citrate, tartaric acid, potassium tartrate and their soluble salts.

[0024] Another preferred embodiment of the gypsum buffer retarder of the present invention is:

[0025] The protein and its derivative retarder is one or a mixture of several of the following protein-based gypsum retarders: 200P, PE, and HG.

[0026] Another preferred embodiment of the gypsum buffer retarder of the present invention is:

[0027] The sucrose is one or a mixture of several of the following: white granulated sugar, brown granulated sugar, and powdered sugar.

[0028] Another preferred embodiment of the gypsum buffer retarder of the present invention is:

[0029] The sucrose is white granulated sugar, which is refined sugar made from molasses extracted from sugarcane and sugar beets.

[0030] The second objective of this invention is:

[0031] A method for preparing a gypsum buffer retarder is provided, comprising the following preparation steps:

[0032] A. Weigh out the coagulant and sucrose according to the proportions;

[0033] B. Place the components weighed in step A into a ball mill and ball mill them;

[0034] C. Weigh out the organic acid and its soluble salt retarder, the protein and its derivative retarder, and the ball-milled substance from step B according to the specified proportions;

[0035] D. Place the components weighed in step C into a dry powder mixer and stir evenly to prepare a gypsum buffer retarder.

[0036] Another preferred embodiment of the preparation method of the gypsum buffer retarder of the present invention is as follows:

[0037] The specific surface area of ​​the material after ball milling in step B is 150-600 m². 2 / kg.

[0038] The gypsum buffer retarder of this invention has a simple production process and features advantages such as minimal strength loss, shortened open time and final setting time interval, good compatibility, low fluctuation, and good stability, thus overcoming the inherent defects of traditional retarder. This gypsum buffer retarder can be used to adjust and control the setting time during the production of gypsum mortars such as jointing gypsum, bonding gypsum, plastering gypsum, gypsum putty, and gypsum self-leveling gypsum.

[0039] The advantages of this invention are:

[0040] (1) In this invention, sucrose and a coagulant are first ball-milled together. The coagulant can provide the crystal nuclei required for the hydration reaction of gypsum, thereby increasing the hydration rate. Ball milling can reduce the particle size of the coagulant and increase its specific surface area. For the same weight of coagulant, ball milling can provide more crystal nuclei and improve the coagulation efficiency.

[0041] (2) In this invention, sucrose is used as a barrier agent. Sucrose is a polyhydroxy compound. When it is ball-milled with the coagulant, its surface has strong polarity and will coat the surface of the coagulant. In the gypsum slurry, the sucrose dissolves first. After the sucrose dissolves, the coagulant inside begins to play its coagulation role. Sucrose can block the effect of the coagulant in the early stage.

[0042] (3) This invention uses a ball mill and mixes accelerators, sucrose, organic acids and their soluble salts as retarders, and proteins and their derivatives as retarders in a certain proportion to produce a gypsum buffer retarder. Before the workable time of gypsum mortar, the retarding effect of organic acids and their soluble salts as retarders and proteins and their derivatives as retarders is dominant. After the workable time, the accelerator's setting effect is dominant. During the setting process of gypsum mortar, the combined action of sucrose, accelerators, organic acids and their soluble salts as retarders, and proteins and their derivatives as retarders can reduce the fluctuation in the setting time of gypsum mortar products caused by the fluctuation in the setting time of gypsum raw materials. The use of the gypsum buffer retarder reduces the interval between the workable time and the final setting time of gypsum mortar, thus reducing strength loss.

[0043] (4) The raw materials used in this invention are all powders. When mixing, they can be produced directly using existing dry powder mortar production equipment. The production process is simple and conducive to the promotion and application of gypsum buffer retarder.

[0044] (5) After extensive and in-depth research, the inventors developed a new type of gypsum buffer retarder and its preparation method for the first time. By ball milling the coagulant and sucrose, adding an appropriate amount of organic acid and its soluble salt retarder, protein and its derivative retarder, and referring to the buffer solution mechanism, the compatibility and stability were improved, and the fluctuation and strength loss were reduced. Based on this, the present invention was completed.

[0045] (6) Furthermore, in a preferred embodiment of the present invention, industrial by-product gypsum from solid waste can be used as a coagulant, responding to the national policy on the comprehensive utilization of solid waste. As industrial waste discharged from industrial production, my country generates a huge amount of industrial by-product gypsum, with a comprehensive utilization rate of approximately 50%. The large-scale accumulation of industrial by-product gypsum has led to serious environmental pollution and resource waste problems. Therefore, exploring ways to increase the application of industrial by-product gypsum in the construction field to meet the needs of the building materials market is one of the future development directions for gypsum. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the ball milling process in the preparation of the gypsum buffer retarder of the present invention.

[0047] Figure 2 This is a schematic diagram of the production process of the gypsum buffer retarder of the present invention. Detailed Implementation

[0048] To make the application, technical solution, and advantages of this invention clearer, the invention is described in detail with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Any simple modifications to the preparation method of this invention based on the inventive concept are within the scope of protection of this invention.

[0049] The relevant terms used in this invention include:

[0050] According to Roland and Rijel, a setting accelerator is a substance that increases the solubility of hemihydrate gypsum. When hemihydrate gypsum is added to water, it first dissolves, then precipitates as dihydrate gypsum. As hydration continues, the number of dihydrate gypsum crystals increases, while the free water in the slurry decreases due to hydration, leading to increased slurry consistency. The bonding between crystals gradually strengthens, and friction and adhesion forces are generated between particles, causing the slurry to gradually lose its plasticity and harden, thus acquiring strength. Setting accelerators can accelerate the setting of gypsum and increase the rate of heat release.

[0051] This invention preferably uses natural dihydrate gypsum, desulfurized dihydrate gypsum, phosphodihydrate gypsum, and potassium sulfate as coagulants, and more preferably uses natural dihydrate gypsum. Based on the source of the gypsum raw materials, gypsum can be divided into natural gypsum and industrial by-product gypsum. Industrial by-product gypsum can be further divided into desulfurized gypsum, phosphodihydrate, citric acid gypsum, fluorogypsum, etc.

[0052] Sucrose is a disaccharide with a sweet taste and no odor. It is readily soluble in water and glycerol, and slightly soluble in alcohol. Sucrose is found almost universally in the leaves, flowers, stems, seeds, and fruits of plants. It is particularly abundant in sugarcane and beet juice. Sucrose is sweet and is an important food and sweetener. It is classified into white granulated sugar, brown sugar, fine white sugar, rock sugar, and yellow sugar.

[0053] This invention uses sucrose as a barrier agent. When sucrose and the coagulant are ball-milled together, sucrose, being a polyhydroxy compound, has a highly polar surface and will coat the surface of the coagulant. In the gypsum slurry, sucrose dissolves first. Only after the sucrose dissolves can the coagulant inside begin to exert its coagulation effect. Sucrose can block the effect of the coagulant in the early stage.

[0054] Organic acids and their soluble salts are used as retardering agents, mainly including citric acid, sodium citrate, tartaric acid, potassium tartrate, acrylic acid, and sodium acrylate. Organic acids complex calcium ions, hindering the dissolution of hemihydrate gypsum, reducing the supersaturation of the liquid phase, and slowing down the rate of crystal nucleation formation during the hydration induction stage of gypsum, thus achieving a retarding effect.

[0055] Protein-based retarder is a new type of gypsum retarder, which is divided into protein hydrolysis products, amino acid condensation polymers, etc. Its retarding mechanism is that after the protein-based retarder is dissolved in water, it forms a colloid, which is adsorbed on the surface of gypsum dihydrate and forms a gel film, which hinders the further growth of gypsum crystals.

[0056] A method for preparing a gypsum buffer retarder includes the following preparation steps:

[0057] A. Weigh out the coagulant and sucrose according to the proportions;

[0058] B. Place the components weighed in step A into a ball mill and ball mill them;

[0059] C. Weigh out the organic acid and its soluble salt retarder, the protein and its derivative retarder, and the ball-milled substance from step B according to the specified proportions;

[0060] D. Place the components weighed in step C into a dry powder mixer and stir evenly to prepare a gypsum buffer retarder.

[0061] Another preferred embodiment of the preparation method of the gypsum buffer retarder of the present invention is as follows:

[0062] The specific surface area of ​​the material after ball milling in step B is 150-600 m². 2 / kg.

[0063] Example 1

[0064] A gypsum buffer retarder is prepared by mixing the ingredients according to the preparation method described above in the following weight percentage ratios.

[0065] Natural dihydrate gypsum 35%, white sugar 5%, citric acid 35%, PE 25%.

[0066] Example 2

[0067] A gypsum buffer retarder is prepared by ball milling and mixing according to the preparation method described above, in the following weight percentage ratios.

[0068] Natural dihydrate gypsum 35%, white sugar 5%, citric acid 35%, PE 25%.

[0069] Example 3

[0070] A gypsum buffer retarder is prepared by ball milling and mixing according to the preparation method described above, in the following weight percentage ratios.

[0071] Natural dihydrate gypsum 15%, desulfurized dihydrate gypsum 15%, phosphate dihydrate gypsum 15%, potassium sulfate 15%, white sugar 10%, citric acid 15%, PE 15%.

[0072] Example 4

[0073] A gypsum buffer retarder is prepared by ball milling and mixing according to the preparation method described above, in the following weight percentage ratios.

[0074] The composition is: 60% desulfurized dihydrate gypsum, 5% brown sugar, 5% granulated sugar, 15% citric acid, and 15% PE.

[0075] Example 5

[0076] A gypsum buffer retarder is prepared by ball milling and mixing according to the preparation method described above, in the following weight percentage ratios.

[0077] Natural dihydrate gypsum 20%, white sugar 1%, citric acid 15%, sodium citrate 15%, tartaric acid 15%, potassium tartrate 10%, HG 24%.

[0078] Example 6

[0079] A gypsum buffer retarder is prepared by ball milling and mixing according to the preparation method described above, in the following weight percentage ratios.

[0080] Desulfurized dihydrate gypsum 20%, white sugar 1%, tartaric acid 34%, 200P 15%, PE 15%, HG 15%.

[0081] Example 7

[0082] A gypsum buffer retarder is prepared by ball milling and mixing according to the preparation method described above, in the following weight percentage ratios.

[0083] 45% gypsum dihydrate, 5% white sugar, 30% sodium citrate, 15% potassium tartrate, and 5% 200P.

[0084] Example 8

[0085] A gypsum buffer retarder is prepared by ball milling and mixing according to the preparation method described above, in the following weight percentage ratios.

[0086] Desulfurized dihydrate gypsum 15%, phosphorus dihydrate gypsum 15%, potassium sulfate 15%, white sugar 2%, brown sugar 4%, granulated sugar 4%, sodium citrate 15%, potassium tartrate 15%, 200P 5%, PE 5%, HG 5%.

[0087] Comparative Example 1

[0088] Protein and its derivative retarder, formulated in the following weight percentages:

[0089] 200P 100%.

[0090] Comparative Example 2

[0091] Organic acids and their soluble salts as retarder and proteins and their derivatives as retarder, mixed in the following weight percentages:

[0092] Citric acid 50%, PE 50%.

[0093] Performance testing of gypsum buffer retarder

[0094] The test formulation, by weight percentage, consisted of: 99.66% gypsum + 0.3% cellulose ether + 0.04% retarder. The gypsum was desulfurized building gypsum, meeting the performance requirements of GB / T 9776 standard. The cellulose ether was hydroxypropyl methylcellulose ether with a viscosity of 30,000-70,000 mPa·s (2% aqueous solution, 20℃, Brookfield RV).

[0095] The gypsum buffer retarder prepared in Examples 1-8 and Comparative Examples 1-2 were mixed evenly according to the test formula to prepare mortar. The prepared mortar was tested for standard diffusivity, water addition, final setting time, flexural strength and compressive strength according to standard GB / T 28627-2012. The workability time of the prepared mortar was tested with reference to JC / T517-2004.

[0096] The test results are shown in Table 1 below.

[0097] Table 1 Performance Test Results

[0098]

[0099]

[0100] The results in Table 1 show that the performance indicators of Examples 1-8 are generally superior to those of Comparative Examples 1 and 2, especially in terms of workability and final setting interval, flexural strength, and compressive strength. Example 2, which involved ball milling, showed superior performance indicators compared to Example 1, which did not require ball milling. Ball milling played a significant role in improving the performance of the gypsum buffer retarder. Considering its other advantages, the gypsum buffer retarder of this invention is an excellent choice for adjusting and controlling the setting time in the production of gypsum mortars such as jointing plaster, bonding plaster, plastering plaster, gypsum putty, and gypsum self-leveling plaster.

[0101] In summary, the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any changes, modifications, and evolutions made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content shall be considered equivalent embodiments of the present invention. Furthermore, any changes, modifications, and evolutions made to the above embodiments based on the essential technology of the present invention shall still fall within the protection scope of the present invention.

[0102] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] Experimental methods not specified in this invention are generally performed under conventional conditions or as recommended by the manufacturer.

[0104] Unless otherwise stated, the various optimized technical solutions in this invention can be combined with each other.

[0105] Unless otherwise stated, percentages and parts are weight percentages and weight parts.

[0106] Experimental methods not specified in the instructions and examples are generally performed under standard conditions or as recommended by the manufacturer.

[0107] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be used in the methods of this invention.

Claims

1. A gypsum buffer retarder, characterized in that: It comprises the following components in parts by weight: 20-60 parts of coagulant accelerator 1-10 parts sucrose 15–55 parts of organic acids and their soluble salts as retarder 5-45 parts of protein and its derivative retarder; First, the coagulant and sucrose are ball-milled to obtain a ball-milled mixture with a specific surface area of ​​150-600 m². 2 / kg; then the ball-milled mixture is dry-mixed with the organic acid and its soluble salt retarder, and the protein and its derivative retarder.

2. The gypsum buffer retarder according to claim 1, characterized in that: The coagulant is gypsum, an industrial byproduct of solid waste.

3. The gypsum buffer retarder according to claim 1, characterized in that: The coagulant is one or a combination of several of the following: natural dihydrate gypsum, desulfurized dihydrate gypsum, phosphate dihydrate gypsum, and potassium sulfate.

4. The gypsum buffer retarder according to claim 1, characterized in that: The organic acid and its soluble salt retarder are one or a combination of several of citric acid, sodium citrate, tartaric acid, and potassium tartrate.

5. The gypsum buffer retarder according to claim 1, characterized in that: The protein and its derivative retarder is one or a combination of several of the following protein-based gypsum retarder types: 200P, PE, and HG.

6. The gypsum buffer retarder according to claim 1, characterized in that: The sucrose is one or a combination of several of the following: white granulated sugar, brown granulated sugar, and powdered sugar.

7. The gypsum buffer retarder according to claim 1, characterized in that: The sucrose is white granulated sugar, which is refined sugar made from molasses extracted from sugarcane and sugar beets.

8. A method for preparing a gypsum buffer retarder according to any one of claims 1 to 7, characterized in that: It includes the following preparation steps: A. Weigh out the coagulant and sucrose according to the specified proportions; B. Place the components weighed in step A into a ball mill and ball mill them; C. Weigh out the organic acid and its soluble salt retarder, the protein and its derivative retarder, and the ball-milled substance from step B according to the specified proportions; D. Place the components weighed in step C into a dry powder mixer and stir evenly to prepare a gypsum buffer retarder.

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