Modification method of polymer with stable repeated swelling performance, polymer and application

Abstract

The present invention belongs to the technical field of cement-based materials, and provides a modification method, polymer and application of a polymer with stable repeated swelling performance. Among them, the modification method of the polymer with stable repeated swelling performance includes adding the original super absorbent polymer to a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, stirring for a set time period, and then filtering out the mixture; washing the filtered mixture with an aqueous solution, and stopping washing when the pH range of the solution is 4-8; vacuum drying the washed mixture until constant weight is obtained to obtain a modified super absorbent polymer after drying; crushing the modified super absorbent polymer after drying to obtain a modified super absorbent polymer with a set particle size. The super absorbent polymer after modification has its initial swelling performance suppressed, and the super absorbent polymer after modification has long-term water absorption and water release cycle performance, which can improve its durability in cement-based materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of cement-based materials, and in particular relates to a modification method of a high polymer with stable repeated swelling performance, the polymer and its application. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] To address the internal shrinkage problem of high-performance concrete, superabsorbent polymers (SAPs) with excellent water absorption and retention properties are often used as internal curing agents. This effectively maintains humidity within the concrete, reducing shrinkage and microcracks. However, adding traditional SAPs (Super Absorbent Polymers) to cementitious materials presents the following issues:

[0004] (1) However, due to the excellent water absorption properties of SAP, it can absorb a large amount of water in aqueous solution, but it has poor swelling properties in environments such as seawater and salt.

[0005] (2) If SAP itself does not have good repeated swelling properties, it will affect the durability of SAP in cement-based materials, and thus affect the long-term durability of the building structure.

[0006] (3) Superabsorbent polymers can instantly absorb a large amount of mixing water, thereby affecting the workability of cement-based materials and, in turn, the construction effect. Summary of the Invention

[0007] To address the technical problems encountered in the aforementioned background art, the present invention provides a method for modifying a polymer with stable repeated swelling properties, a polymer, and its application. The modified superabsorbent polymer suppresses its initial swelling, effectively resolving the problem of poor workability. Furthermore, the modified superabsorbent polymer exhibits long-term water absorption and release cycles, improving its durability in cement-based materials.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The first aspect of the present invention provides a method for modifying a polymer having stable repeated swelling properties.

[0010] A method for modifying a polymer having stable repeated swelling properties, comprising:

[0011] The original superabsorbent polymer is added to a calcium hydroxide solution having a concentration of 0.1-0.5 mol / L, stirred for a set period of time, and then the mixture is filtered;

[0012] The filtered mixture is washed with an aqueous solution, and the washing is stopped when the pH range of the solution is 4-8;

[0013] The cleaned mixture is vacuum dried until constant weight is obtained to obtain a dried modified superabsorbent polymer;

[0014] The dried modified super absorbent polymer is pulverized to obtain a modified super absorbent polymer with a predetermined particle size.

[0015] As an embodiment, modified superabsorbent polymers with different particle sizes are obtained according to different pulverization times.

[0016] As an embodiment, the dried modified super absorbent polymer is placed in a grinder for grinding.

[0017] As an embodiment, before adding the original super absorbent polymer to the calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, the method further comprises:

[0018] Prepare a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L.

[0019] As an embodiment, the process for preparing a calcium hydroxide solution having a concentration of 0.1-0.5 mol / L is as follows:

[0020] Weigh a set mass of calcium hydroxide powder, put it into a beaker and stir it. After stirring at a set speed for a set time, a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L can be obtained.

[0021] As an embodiment, in the process of a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, the method further comprises:

[0022] Coating prevents carbonization, and stirring accelerates the dissolution of calcium hydroxide.

[0023] As an embodiment, before adding the original super absorbent polymer to the calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, the process further comprises:

[0024] Filter the calcium hydroxide solution with a concentration of 0.1-0.5 mol / L to remove excess precipitate.

[0025] As an embodiment, a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L is pre-poured into a three-necked flask and stirring is started;

[0026] Pour the original super absorbent polymer into the three-necked flask along the opening and mix it with a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, and stir continuously until the stirring time reaches the set time.

[0027] A second aspect of the present invention provides a modified superabsorbent polymer.

[0028] A modified superabsorbent polymer is prepared by the steps of the above-mentioned method for modifying a polymer with stable repeated swelling performance.

[0029] The third aspect of the present invention provides the use of the modified superabsorbent polymer.

[0030] The modified superabsorbent polymer as described above is applied to cement-based materials.

[0031] The beneficial effects of the present invention are:

[0032] (1) The present invention uses calcium hydroxide solution to modify the super absorbent polymer. After the modification, the initial swelling performance of the super absorbent polymer is suppressed, which can effectively solve the problem of poor workability. In addition, the super absorbent polymer after the modification has long-term water absorption and release cycle performance, which can improve its durability in cement-based materials.

[0033] (2) The modified superabsorbent polymer of the present invention has stable swelling properties. After repeated swelling in alkaline solutions such as synthetic seawater, its swelling properties can reach more than 70% of the initial swelling properties, and has good repeated swelling properties.

[0034] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0036] Figure 1 This is a modification device for the super absorbent polymer in an embodiment of the present invention.

[0037] Figure 2 1 is the calcium distribution of the modified and unmodified super absorbent polymers in the embodiments of the present invention.

[0038] Figure 3 This is a repeated swelling performance test (synthetic seawater) of the modified and unmodified SAP in the examples of the present invention.

[0039] Figure 4 This is the effect of modified and unmodified SAP on the workability of cement-based materials in the examples of the present invention.

[0040] Figure 5This is a flow chart of a method for modifying a polymer with stable repeated swelling performance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0044] In one or more embodiments, a method for modifying a polymer having stable repeated swelling properties is provided, comprising:

[0045] Step 1: Add the original superabsorbent polymer to a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, stir for a set period of time, and then filter the mixture.

[0046] It should be noted that the original super absorbent polymer can be polyacrylic acid sodium salt absorbent resin commonly used in the market or other existing absorbent resins.

[0047] Among them, the preparation process of polyacrylic acid sodium salt water-absorbing resin commonly used on the market is as follows:

[0048] Acrylic acid is added in a measured amount into a reaction flask, and the stirrer is turned on. Subsequently, 20% NaOH solution is gradually added to make its neutralization degree 60%-90%, and then deionized water is added to dilute it to 30%-60%. N,N-methylenebisacrylamide is added, and the reaction flask is placed in a constant temperature water bath and heated and nitrogen is driven out for two minutes. Potassium persulfate as an initiator is added to react until a viscous colloid is formed in the reaction process, and the reaction is stopped. The polyacrylic acid sodium salt water-absorbing resin is removed, dried, and crushed to obtain the polyacrylic acid sodium salt water-absorbing resin.

[0049] In a specific implementation process, before adding the original super absorbent polymer to the calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, the method further includes: preparing a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L.

[0050] The process for preparing a calcium hydroxide solution having a concentration of 0.1-0.5 mol / L is as follows:

[0051] Weigh a set mass of calcium hydroxide powder, put it into a beaker and stir it. After stirring at a set speed for a set time, a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L can be obtained.

[0052] Specifically, in the process of preparing a calcium hydroxide solution of a certain concentration, the following steps are also included:

[0053] The coating prevents carbonization, and stirring accelerates the dissolution of calcium hydroxide. For example, a magnetic stirrer is used for stirring for 20 minutes to 60 minutes.

[0054] In some specific embodiments, before adding the original super absorbent polymer to the calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, the method further comprises:

[0055] Filter the calcium hydroxide solution with a concentration of 0.1-0.5 mol / L to remove excess precipitate.

[0056] In some optional embodiments, such as Figure 1 As shown, a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L is poured into a three-necked flask in advance and stirring is started;

[0057] The original super absorbent polymer is poured into a three-necked flask along the opening and mixed with a calcium hydroxide solution of a certain concentration, and stirred continuously until the stirring time reaches a set time (eg, 8-30 hours).

[0058] Step 2: The filtered mixture is washed with an aqueous solution, and the washing is stopped when the pH range of the solution is 4-8.

[0059] Step 3: The cleaned mixture is vacuum dried until constant weight is reached to obtain a dried modified superabsorbent polymer.

[0060] Step 4: Grind the dried modified super absorbent polymer to obtain a modified super absorbent polymer with a set particle size.

[0061] For example, the dried modified superabsorbent polymer is put into a grinder for grinding.

[0062] In the specific implementation process, modified super absorbent polymers with different particle sizes are obtained according to different crushing times.

[0063] The performance test process of the modified super absorbent polymer is as follows:

[0064] (1) First, test the average wet weight of the empty tea bags. Place ten empty tea bags (mass m1) in the prepared test solution, leave for 30 seconds, then take them out, remove excess water from the surface with a towel, and weigh the mass of the tea bags (m2). Calculate the average wet weight of the empty tea bags m 空茶袋 .

[0065]

[0066] Where n is the number of empty tea bags.

[0067] (2) A certain mass of dry modified and unmodified superabsorbent polymer (0.1 g to 0.2 g, denoted as m3) was then weighed and placed into a dry empty tea bag. The bag was then immersed in different test solutions for different periods of time. After removal, the surface moisture was wiped dry and the mass (m4) was measured.

[0068] (3) Then, the swelling performance S of SAP is calculated based on the definition of swelling performance: the amount of water absorbed by dry SAP per unit time (g / g) SAP The test results are the average of the three tea bag test results.

[0069]

[0070] (4) The above steps are for one swelling performance test. After one test, the tea bag and the SAP after water absorption are placed in a drying oven (temperature of 30-60°C) until constant weight is reached. Then, the dried SAP is taken out and the next test is performed again according to the above steps. A total of 6 cycles are performed.

[0071] In this embodiment, conventional superabsorbent polymers are soaked in a calcium hydroxide solution of a certain concentration. The modified superabsorbent polymers have stable swelling properties, which can change the initial swelling properties of the superabsorbent polymers, improve the workability of cement-based materials, and enhance the long-term durability of cement-based materials.

[0072] In some embodiments, a modified superabsorbent polymer is provided, which is prepared using the steps of the above-mentioned method for modifying a polymer with stable repeated swelling properties.

[0073] The modified superabsorbent polymer as described above is applied to cement-based materials, and the application process includes the following steps:

[0074] (1) Weigh cement, sand, water, and modified and unmodified superabsorbent polymers; pour the weighed cement, sand, and modified superabsorbent polymer into a mixer and stir for 60 to 120 seconds; then pour the weighed water and stir again for 120 to 180 seconds, and then test the fluidity of the mortar specimen.

[0075] (2) The weights of cement, sand, and water are as follows:

[0076] Cement: sand: water: modified super absorbent polymer = 1:2:0.40: (0.003-0.006).

[0077] (3) The fluidity test of the mortar with modified and unmodified super absorbent polymer was carried out. The experimental results are as follows: Figure 4 shown.

[0078] Specific examples are given below to demonstrate the modification effect of the super absorbent polymer of the present invention.

[0079] Example 1:

[0080] Test the modification effect of super absorbent polymer, the results are as follows Figure 2 shown.

[0081] The modified super absorbent polymer was tested by extracting the dried and crushed modified super absorbent polymer powder, pasting it on the conductive adhesive, spraying gold, and then observing and elemental analysis under an electron microscope. The results are as follows: Figure 2 shown.

[0082] pass Figure 2 It can be seen that the calcium content on the surface of the unmodified super absorbent polymer is only 0.5%, while the calcium content on the surface of the modified super absorbent polymer is 48.8%, and the surface is rich in calcium.

[0083] Example 2:

[0084] The repeated swelling properties of modified and unmodified SAP in synthetic seawater were tested.

[0085] To prepare synthetic seawater, 1 L of solution contains 0.19 g of sodium bicarbonate, 1.47 g of calcium chloride dihydrate, 10.57 g of magnesium chloride hexahydrate, 9.02 g of sodium sulfate decahydrate, 0.75 g of potassium chloride, and 24.08 g of sodium chloride. The corresponding chemical reagents were weighed in this proportion and stirred using a magnetic stirrer. Stirring was stopped when no insoluble matter remained in the solution. This produced synthetic seawater.

[0086] The modified and unmodified super absorbent polymers were then placed in synthetic seawater, and the repeated swelling properties of the super absorbent polymers were tested according to the steps in the performance test process of the modified super absorbent polymers.

[0087] The experimental results are as follows Figure 3 As shown, it can be seen that the swelling performance of the modified superabsorbent polymer in synthetic seawater shows a downward trend, but after 6 cycles, it is found that the swelling performance of the modified superabsorbent polymer can still reach 75% of the initial swelling performance, while the swelling performance of the unmodified superabsorbent polymer after 6 cycles is 61% of the initial state.

[0088] Example 3:

[0089] The effect of modified superabsorbent polymer on the workability of mortar was tested.

[0090] According to the above steps of applying the modified superabsorbent polymer to cement-based materials, the corresponding mortar was prepared and its workability was tested using a jumping table. Figure 4 As shown, it can be seen that since the unmodified super absorbent polymer can absorb more mixing water, which reduces its workability, the fluidity of the mortar mixed with the unmodified super absorbent polymer is only 177.5 mm, but the fluidity of the mortar mixed with the modified super absorbent polymer is 230.6 mm.

[0091] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for modifying a polymer having stable repeated swelling properties, characterized in that: include: Pour 0.1-0.5 mol / L calcium hydroxide solution into a three-necked flask and start stirring; Pour the original super absorbent polymer into the three-necked flask along the opening and mix it with a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, and stir continuously until the stirring time reaches the set time, and then filter the mixture; The filtered mixture is washed with an aqueous solution, and the washing is stopped when the pH range of the solution is 4-8; The cleaned mixture is vacuum dried until constant weight is obtained to obtain a dried modified superabsorbent polymer; The dried modified super absorbent polymer is pulverized to obtain a modified super absorbent polymer with a predetermined particle size.

2. The method for modifying a polymer having stable repeated swelling properties according to claim 1, wherein: According to the different crushing times, modified superabsorbent polymers with different particle sizes are obtained.

3. The method for modifying a polymer having stable repeated swelling properties according to claim 1, wherein: The dried modified super absorbent polymer is placed in a grinder for grinding.

4. The method for modifying a polymer having stable repeated swelling properties according to claim 1, wherein: Before adding the original super absorbent polymer to the calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, the method further comprises: Prepare a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L.

5. The method for modifying a polymer having stable repeated swelling properties according to claim 4, wherein: The process for preparing a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L is as follows: Weigh a set mass of calcium hydroxide powder, put it into a beaker and stir it. After stirring at a set speed for a set time, a calcium hydroxide solution with a concentration of 0.1-0.5 mol / L can be obtained.

6. The method for modifying a polymer having stable repeated swelling properties according to claim 5, wherein: In the process of calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, it also includes: Coating prevents carbonization, and stirring accelerates the dissolution of calcium hydroxide.

7. The method for modifying a polymer having stable repeated swelling properties according to claim 1, wherein: Before adding the original super absorbent polymer to the calcium hydroxide solution with a concentration of 0.1-0.5 mol / L, the method further comprises: Filter the calcium hydroxide solution with a concentration of 0.1-0.5 mol / L to remove excess precipitate.

8. A modified superabsorbent polymer, characterized in that: The polymer is prepared by the steps of the method for modifying a polymer with stable repeated swelling performance as described in any one of claims 1 to 7.

9. Application of the modified super absorbent polymer according to claim 8 to cement-based materials.

Images