Phosphate binder modified by tetrasodium iminodisuccinate and preparation method thereof

Abstract

The invention discloses a phosphate binder modified by tetrasodium iminodisuccinate and a preparation method thereof. The phosphate binder modified by tetrasodium iminodisuccinate is prepared from the following raw materials: 52.100% to 52.587% of industrial phosphoric acid, 11.946% to 12.058% of aluminum hydroxide powder, 1.850% to 1.867% of boric acid, 0.617% to 0.622% of silicate, 1.233% to 1.245% of light magnesium oxide, 0.039% of copper oxide, 0.467% to 1.387% of tetrasodium iminodisuccinate, and 30.828% to 31.115% of water. The invention adopts tetrasodium iminodisuccinate as a modifier, and the prepared modified phosphate binder has the advantages of low viscosity, high bonding strength, good sand sample anti-hygroscopicity, and good fluidity of the prepared molding sand.

Description

Technical Field

[0001] The invention belongs to the field of casting industry, and specifically relates to a phosphate binder modified by tetrasodium iminodisuccinate, and also relates to a preparation method of the phosphate binder modified by tetrasodium iminodisuccinate. Background Art

[0002] As an inorganic casting binder, phosphate binder has its unique excellent disintegration and environmental protection. Compared with organic resin binders, it has the characteristics of low gas emission, good disintegration, non-toxicity and environmental protection. It is a new type of casting binder with great application value. However, compared with traditional organic resin binders, its molding sand fluidity is poor, its performance is unstable, its moisture absorption resistance is poor, and its binder viscosity is high. How to modify phosphate binder, improve its molding sand fluidity, improve its moisture absorption resistance, achieve the same use requirements as traditional organic resin binders, and make it meet the actual production needs is the main problem at present. Summary of the invention

[0003] In order to solve the above-mentioned deficiencies in the art, the purpose of the present invention is to provide a phosphate binder modified by tetrasodium iminodisuccinate, by adding a modifier of a small molecular weight alkaline organic matter, thereby improving the performance of the phosphate binder to a certain extent, having the advantages of low viscosity, high bonding strength, and good anti-hygroscopicity of sand samples, and the prepared molding sand has good fluidity.

[0004] Another object of the present invention is to provide a method for preparing a phosphate binder modified by tetrasodium iminodisuccinate, which is simple, fast, easy to operate and low in cost.

[0005] The present invention achieves one of the objectives by adopting the following technical solution:

[0006] A phosphate binder modified by tetrasodium iminodisuccinate is prepared from the following raw materials by mass percentage:

[0007] Industrial phosphoric acid 52.100%~52.587%, aluminum hydroxide powder 11.946%~12.058%, boric acid 1.850%~1.867%, silicic acid 0.617%~0.622%, light magnesium oxide 1.233%~1.245%, copper oxide 0.039%, tetrasodium iminodisuccinate 0.467%~1.387%, water 30.828%~31.115%.

[0008] Preferably, the aforementioned phosphate binder is prepared from the following raw materials by mass percentage:

[0009]

[0010] The mass percentage of the industrial phosphoric acid is 85%.

[0011] The aluminum hydroxide powder is industrial grade white powder with a particle size of 320 meshes.

[0012] The boric acid is a colorless, slightly pearly crystalline white powder with an effective content of ≥99.9%.

[0013] The silicic acid is a white amorphous powder.

[0014] The light magnesium oxide is a white light powder with an effective content of ≥98.5%.

[0015] The boric acid, silicic acid, light magnesium oxide and copper oxide are all of analytical grade.

[0016] The tetrasodium iminodisuccinate is a colorless to light yellow aqueous solution with an effective content of 33%-35%.

[0017] The water is deionized pure water.

[0018] From the above, tetrasodium iminodisuccinate IDS is an alkaline chelating agent. The anion of tetrasodium iminodisuccinate can form a coordination geometry with metal cations. It has a strong chelating ability for calcium, magnesium, zinc and other transition metal ions, especially for heavy metal elements such as copper, iron, manganese, and nickel. The chelating ability exceeds that of common chelating agents such as EDTA, and the formed chelate has more stable performance.

[0019] Tetrasodium iminodisuccinate (IDS for short) used in the invention can combine with acid radical ions to reduce the acidity of the binder and play a neutralizing role during synthesis and preparation; tetrasodium iminodisuccinate has a strong ability to chelate metal ions; small molecule tetrasodium iminodisuccinate can form stable water-soluble complex molecules with metal ions due to its excellent acid and alkali resistance and high temperature resistance, thereby ensuring that the binder has good stability, thereby ensuring the stability of the fluidity of the molding sand, allowing the added raw materials to participate in the reaction to the maximum extent, generating less residue, reducing the loss of water to ensure that the binder has a lower viscosity, and thus improving the fluidity of the molding sand prepared by the phosphate binder.

[0020] The invention adopts tetrasodium iminodisuccinate as a modifier, which can be connected to a phosphate network structure when added in a small amount, thereby increasing the flexibility of the network structure and the length of the chain segment, thereby significantly reducing the viscosity of the binder; the molding sand prepared by the binder modified by tetrasodium iminodisuccinate has better fluidity, reduces the mold filling resistance, is beneficial to the filling of the sand, and is beneficial to improving the strength of the sand mold, thereby offsetting the influence of the increased neutralization degree to a certain extent; since the binder of the invention has a high neutralization degree, its moisture absorption resistance is significantly improved.

[0021] The following technical solutions are used to achieve the second purpose of this application:

[0022] A method for preparing the aforementioned phosphate binder comprises:

[0023] Add raw materials of industrial phosphoric acid, aluminum hydroxide powder, boric acid, silicic acid, light magnesium oxide, copper oxide, tetrasodium iminodisuccinate and water into a reaction kettle; react until the solution becomes transparent, and remove the bottom precipitate after discharging.

[0024] Specifically, a method for preparing a phosphate binder modified by tetrasodium iminodisuccinate comprises the following steps:

[0025] (1) Add industrial phosphoric acid into a reaction kettle and heat to 180-200°C while stirring;

[0026] (2) adding aluminum hydroxide powder to the reaction kettle of step (1) above, and continuing to stir until the reaction solution becomes transparent;

[0027] (3) adding one quarter of the total amount of water to the reaction kettle in step (2), and heating and stirring until the temperature of the reaction solution returns to the temperature before adding water;

[0028] (4) Adding boric acid to the reaction kettle of step (3) above, and continuing to heat and stir until the reaction solution becomes transparent;

[0029] (5) adding silicic acid to the reaction kettle of step (4) above, and continuing heating and stirring until the reaction solution becomes transparent;

[0030] (6) adding one quarter of the total amount of water to the reaction kettle in step (5), and heating and stirring until the temperature of the reaction solution returns to the temperature before adding water;

[0031] (7) Adding light magnesium oxide to the reaction kettle of step (6) above, and continuing to heat and stir until the reaction solution becomes transparent;

[0032] (8) Add copper oxide to the reaction kettle of step (7) above, and continue heating and stirring until the reaction solution becomes transparent;

[0033] (9) adding one quarter of the total amount of water to the reaction kettle in step (8), and heating and stirring until the temperature of the reaction solution returns to the temperature before adding water;

[0034] (10) adding tetrasodium iminodisuccinate to the reaction kettle of step (9) above, and continuing heating and stirring until the reaction solution becomes transparent;

[0035] (11) Add the remaining water of the total water volume to the reaction kettle of the above step (10), continue heating and stirring until the reaction solution is transparent and clear, remove the bottom precipitate after discharging the material, and obtain the phosphate binder modified by tetrasodium iminodisuccinate.

[0036] From the above, the preparation of binder synthesis according to this step is to ensure that the corresponding reaction product is obtained in each step, so as to obtain a binder with stable comprehensive performance; the tetrasodium iminodisuccinate is added at the end because it has a strong ability to chelate metal ions and can form a stable water-soluble complex molecule with metal ions, which ensures that the binder has good stability, so that the added raw materials can participate in the reaction to the maximum extent, less residue is produced, and the loss of water is reduced to ensure that the binder has a lower viscosity, so that the fluidity of the molding sand prepared by the phosphate binder is improved; water is added multiple times, and added after each step of synthesis is clarified, which plays a diluting role to ensure that the viscosity of the binder is reduced, which is conducive to the next step of synthesis and preparation. At the same time, the prepared binder can be stored stably for a long time, is not easy to precipitate crystals, and has a very stable viscosity.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention proposes to modify the existing phosphate binder by using alkaline organic tetrasodium iminodisuccinate. The reason why the alkaline organic tetrasodium iminodisuccinate with a small molecule is used for modification is that the alkaline organic tetrasodium iminodisuccinate with a small molecule has excellent compatibility, acid and alkali resistance, high temperature resistance, and more stable performance, while the macromolecular alkaline organic matter is greatly affected by the environmental pH value and is easily decomposed by heat at high temperature, which is not conducive to the synthesis and preparation of the phosphate binder, resulting in its unstable performance. The present invention adds a modifier of alkaline organic matter with a small molecular weight, improves the performance of the phosphate binder to a certain extent, has the advantages of low viscosity, high bonding strength, and good sand-like anti-hygroscopicity, and the prepared molding sand has good fluidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a comparison chart of the phosphate binder modified by tetrasodium iminodisuccinate in Example 2 and the unmodified phosphate binder in the comparative example;

[0040] Figure 2 A sample diagram showing the adhesive prepared in Example 2 of the present invention being applied to a sample;

[0041] Figure 3 This is a sample diagram showing the adhesive prepared in Example 1 of the present invention being applied to a sample. DETAILED DESCRIPTION

[0042] The features and advantages of the present invention can be further understood through the following examples and detailed descriptions. The examples provided are merely illustrative of the methods of the present invention and are not intended to limit the remainder of the present invention in any way.

[0043] As mentioned above, the current phosphate binder has the disadvantages of unstable performance, poor moisture absorption resistance, high viscosity, poor sand fluidity, etc. In view of the above problems, the present application provides a phosphate binder modified by tetrasodium iminodisuccinate and a preparation method thereof.

[0044] The technical solution of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0045] It is particularly important to point out that similar substitutions and modifications made to the present application are obvious to those skilled in the art, and they are all deemed to be included in the present application. Relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present application to implement and apply the technology of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments.

[0046] If no specific conditions are specified in this application, the preparation shall be carried out under conventional conditions or the conditions recommended by the manufacturer. The raw materials or excipients used, as well as the reagents or instruments used, for which the manufacturers are not specified, are all conventional products that can be obtained commercially.

[0047] According to the technical concept of the present application, a phosphate binder and a preparation method thereof are provided.

[0048] The application is described in detail below.

[0049] A phosphate binder modified by tetrasodium iminodisuccinate is prepared from the following raw materials by mass percentage:

[0050] Industrial phosphoric acid 52.100%~52.587%;

[0051] Aluminum hydroxide powder 11.946%~12.058%;

[0052] Boric acid 1.850%~1.867%;

[0053] Silicic acid 0.617%~0.622%;

[0054] Light magnesium oxide 1.233%~1.245%;

[0055] Copper oxide 0.039%;

[0056] Tetrasodium iminodisuccinate 0.467%~1.387%;

[0057] Water 30.828%~31.115%.

[0058] The mass percentage of the industrial phosphoric acid is 85%.

[0059] Aluminum hydroxide powder is industrial grade white powder with a particle size of 320 mesh.

[0060] Boric acid is a colorless, slightly pearly crystalline white powder with an effective content of ≥99.9%.

[0061] Silicic acid is a white amorphous powder.

[0062] Light magnesium oxide is a white light powder with an effective content of ≥98.5%.

[0063] Boric acid, silicic acid, light magnesium oxide, and copper oxide were all analytically pure;

[0064] Tetrasodium iminodisuccinate is a colorless to pale yellow aqueous solution with an effective content of 33%-35%.

[0065] The water is deionized pure water.

[0066] The phosphate binder modified by tetrasodium iminodisuccinate of the present application is based on the following principle: tetrasodium iminodisuccinate is an alkaline organic substance, which is characterized by being easily soluble in water and soluble in acid. After testing, when a very small amount of phosphate binder modified by tetrasodium iminodisuccinate is added, the strength of the prepared sand sample is improved, the hygroscopicity of the sand sample is improved, the fluidity of the molding sand is improved, and the viscosity of the binder is significantly reduced.

[0067] When the addition amount of tetrasodium iminodisuccinate modified phosphate binder is 2.5% of the sand mass, the instant tensile strength of the sand sample can reach a maximum of 1.74MPa, the 6h tensile strength can reach 1.68MPa, the instant flexural strength of the sand sample can reach a maximum of 4.27MPa, the 24h flexural strength can reach 3.38MPa, and the viscosity drops from 194.3mPa·s to about 171mPa·s.

[0068] The reason for the above effect is that tetrasodium iminodisuccinate can combine with acid radical ions and form stable water-soluble complex molecules with metal ions such as aluminum ions through chelation. The above water-soluble complex molecules play a key role in the stability and water retention of the modified binder, and in an acidic environment, it is connected to the phosphoric acid network structure, increasing the flexibility of the network structure and the length of the main chain, thereby enhancing its wrapping effect and bonding performance, thereby improving the performance of the above modified binder. At the same time, tetrasodium iminodisuccinate is alkaline and has a certain neutralizing effect on phosphates, which can improve the hygroscopicity of the sample. In addition, the addition of silicate, boric acid, and light magnesium oxide further enhances the high temperature resistance of the phosphate binder, and affects the strength and hygroscopicity of the sand mold.

[0069] The present application is described in detail below with reference to specific embodiments.

[0070] Example 1

[0071] Preparation of phosphate binder modified by tetrasodium iminodisuccinate

[0072] 1. Raw material ratio

[0073] 169g 85% industrial phosphoric acid, 38.75g 320 mesh aluminum hydroxide powder, 6g boric acid, 2g silicic acid, 4g light magnesium oxide, 0.125g copper oxide, 1.5g tetrasodium iminodisuccinate, and 100g purified water.

[0074] 2. Preparation steps

[0075] (1) Add industrial phosphoric acid into a reaction kettle and heat to 180-200°C while stirring;

[0076] (2) adding aluminum hydroxide powder into the reaction kettle and continuing to stir until the reaction solution becomes transparent;

[0077] (3) Add 25 g of water and heat with stirring until the temperature of the reaction solution returns to the temperature before adding water;

[0078] (4) Add boric acid powder and continue heating and stirring until the reaction solution becomes transparent;

[0079] (5) Add silicic acid powder and continue heating and stirring until the reaction solution becomes transparent;

[0080] (6) Add 25 g of water and heat with stirring until the temperature of the reaction solution returns to the temperature before adding water;

[0081] (7) adding light magnesium oxide powder and continuing heating and stirring until the reaction solution becomes transparent;

[0082] (8) Add copper oxide powder and continue heating and stirring until the reaction solution becomes transparent;

[0083] (9) Add 25 g of water and heat with stirring until the temperature of the reaction solution returns to the temperature before adding water;

[0084] (10) adding tetrasodium iminodisuccinate, and continuing heating and stirring until the reaction solution becomes transparent;

[0085] (11) Add 25 g of water, continue heating and stirring until the reaction solution is transparent and clear, and remove the bottom precipitate after discharging to obtain the phosphate binder modified by tetrasodium iminodisuccinate.

[0086] Example 2

[0087] Preparation of phosphate binder modified by tetrasodium iminodisuccinate

[0088] 1. Raw material ratio

[0089] 169g 85% industrial phosphoric acid, 38.75g 320 mesh aluminum hydroxide powder, 6g boric acid, 2g silicic acid, 4g light magnesium oxide, 0.125g copper oxide, 3g tetrasodium iminodisuccinate, and 100g purified water.

[0090] 2. The preparation steps are the same as those in Example 1;

[0091] The modified phosphate binder prepared is as follows Figure 1 shown.

[0092] Example 3

[0093] Preparation of phosphate binder modified by tetrasodium iminodisuccinate

[0094] 1. Raw material ratio

[0095] 169g 85% industrial phosphoric acid, 38.75g 320 mesh aluminum hydroxide powder, 6g boric acid, 2g silicic acid, 4g light magnesium oxide, 0.125g copper oxide, 4.5g tetrasodium iminodisuccinate, and 100g pure water.

[0096] 2. The preparation steps are the same as those in Example 1.

[0097] Comparative Example 1

[0098] Preparation of phosphate binder without modification by tetrasodium iminodisuccinate

[0099] 1. Raw material ratio:

[0100] 169g 85% industrial phosphoric acid, 38.75g 320 mesh aluminum hydroxide powder, 6g boric acid, 2g silicic acid, 4g light magnesium oxide, 0.125g copper oxide, and 100g pure water.

[0101] 2. Preparation steps:

[0102] (1) Add industrial phosphoric acid into a reaction kettle and heat to 180-200°C while stirring;

[0103] (2) adding aluminum hydroxide powder into the reaction kettle and continuing to stir until the reaction solution becomes transparent;

[0104] (3) Add 25 g of water and heat with stirring until the temperature of the reaction solution returns to the temperature before adding water;

[0105] (4) Add boric acid powder and continue heating and stirring until the reaction solution becomes transparent;

[0106] (5) Add silicic acid powder and continue heating and stirring until the reaction solution becomes transparent;

[0107] (6) Add 25 g of water and heat with stirring until the temperature of the reaction solution returns to the temperature before adding water;

[0108] (7) adding light magnesium oxide powder and continuing heating and stirring until the reaction solution becomes transparent;

[0109] (8) Add copper oxide powder and continue heating and stirring until the reaction solution becomes transparent;

[0110] (9) Add 50 g of water, heat and stir until the temperature of the reaction solution returns to the temperature before adding water, thereby obtaining a phosphate binder that is not modified with tetrasodium iminodisuccinate.

[0111] Test example

[0112] The phosphate binder modified with tetrasodium iminodisuccinate prepared in the above Examples 1-3 and Comparative Example 1 or the phosphate binder not modified with tetrasodium iminodisuccinate was used to prepare sand molds and their performance was tested:

[0113] 1. Viscosity test: The viscosity of the phosphate binders prepared in Examples 1 to 3 and Comparative Example 1 was tested using a digital viscometer, using a No. 1 rotor, a rotation speed of 12 RPM, and a temperature of 25°C.

[0114] 2. Fluidity of molding sand: The fluidity of molding sand is tested by the side hole mass method. The test method is as follows: a small hole with a diameter of 12 mm is opened on the side of the cylindrical standard sample tube, which is first plugged with a plunger. Weigh 185g of the sample, pour it into the sample tube, and then place it on the hammer-type sample making machine. Pull out the plunger and pound it 10 times, and use the top sample column to push the sample out. Scrape off the sand left in the small hole and weigh it together with the squeezed sand. The mass fraction of the sample is used as the fluidity index of the molding (core) sand. The calculation formula is:

[0115]

[0116] Where, η is the fluidity of the mold (core) sand (%); mA ——Mass of sand passing through the leakage hole (g); m B ——Original sample mass (g).

[0117] Table 1 Test results of binder viscosity and molding sand fluidity

[0118]

[0119] From the results in Table 1, it can be seen that the viscosity of the adhesives prepared in Examples 1-3 is about 171 MPa·s, and the viscosity of the adhesive prepared in Comparative Example 1 is 194.3 MPa·s.

[0120] The fluidity of the molding sand made with the binders prepared in Examples 1-3 ranges from 1.84% to 1.89%; the fluidity of the molding sand made with the binder prepared in Comparative Example 1 is 1.56%.

[0121] The results show that after adding the modifier tetrasodium iminodisuccinate, the viscosity of the binder is reduced, and the fluidity of the molding sand prepared therefrom is significantly improved, with the fluidity increasing by 18% to 21%.

[0122] 3. Sample preparation: Weigh 50 g of the binder of Examples 1-3 and Comparative Example 1, and prepare samples according to the following methods:

[0123] Weigh 50g of phosphate binder modified by tetrasodium iminodisuccinate or phosphate binder not modified by tetrasodium iminodisuccinate, and add 6g of KH-550 and 6g of 12.5% ​​oxalic acid aqueous solution. First add KH-550 and mix the sand for 50s, then add the binder and oxalic acid aqueous solution and mix the sand for 120s, add to 2000g of roasted sand (50 / 100 mesh), stir well, fill the stirred sand into a sand shooting mold, use a sand shooting machine to shoot sand for 4 seconds, heat at 150°C, heat for 2 minutes when preparing tensile sand samples, and heat for 3 minutes when preparing bending sand samples.

[0124] 4. Performance test:

[0125] (1) Testing the tensile strength of sand samples: Test the immediate tensile strength of sand samples after hardening and the tensile strength after 6 hours (45%-55% RH constant humidity storage) and compare them (6 samples are tested in each group, and the average is taken after removing the highest and lowest values).

[0126] (2) Testing the flexural strength of sand samples: Testing the immediate flexural strength and 24-hour flexural strength of sand samples after hardening (45%-55% RH constant humidity storage) and comparing them (6 samples were tested in each group, and the average was taken after removing the highest and lowest values).

[0127] Table 2 Performance test results (1)

[0128]

[0129] From the results in Table 2, it can be seen that the average instant tensile strength of the sand molds prepared in Examples 1-3 ranges from 1.66-1.74MPa, and the average 6h tensile strength ranges from 1.52-1.68Mpa; the average instant tensile strength of the sand mold prepared in Comparative Example 1 is 1.58MPa, and the average 6h tensile strength is 1.33Mpa. In contrast, the instant tensile strength and 6h tensile strength of Examples 1-3 are higher than those in the comparative example, and the increase is more obvious.

[0130] The results show that by adding a small amount of tetrasodium iminodisuccinate to the binder, the immediate hardening strength and 6-hour strength (45%-55% RH constant humidity warehouse) of the sand sample are significantly improved, the moisture absorption resistance is also improved, and the storage stability is better.

[0131] Table 3 Performance test results (2)

[0132]

[0133] From the results in Table 3 above, it can be seen that the average range of the instant bending strength of the sand mold prepared in Examples 1-3 is 4.08-4.27MPa, and the average range of the 24h bending strength is 3.02-3.38MPa; the average instant bending strength of the sand mold prepared in Comparative Example 1 is 3.84MPa, and the average 24h bending strength is 2.63MPa. In contrast, the strength of the sand samples in Examples 1-3 after storage for 24 hours is higher than that in the comparative example on average, indicating that the moisture absorption resistance of the examples is better than that of the comparative example.

[0134] The results show that compared with the phosphate binder without adding a small amount of tetrasodium iminodisuccinate (2.5wt%), the instant hardening flexural strength and 24-hour flexural strength (45%-55%RH constant humidity storage) of the sand sample are significantly improved, the moisture absorption resistance is also improved, and the viscosity of the binder is lower and the storage stability is better.

[0135] The above results show that the phosphate binder modified by tetrasodium iminodisuccinate has good fluidity of the molding sand prepared by the binder, and the binder has the advantages of high bonding strength, low viscosity and anti-hygroscopicity of the sand sample.

[0136] The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. It should be noted that, for ordinary technicians in this technical field, several improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A phosphate binder modified by tetrasodium iminodisuccinate, characterized in that: It is prepared from the following raw materials by mass percentage: Industrial phosphoric acid 52.100%~52.587%, aluminum hydroxide powder 11.946%~12.058%, boric acid 1.850%~1.867%, silicic acid 0.617%~0.622%, light magnesium oxide 1.233%~1.245%, copper oxide 0.039%, tetrasodium iminodisuccinate 0.467%~1.387%, water 30.828%~31.115%.

2. The phosphate binder modified by tetrasodium iminodisuccinate according to claim 1, characterized in that: It is prepared from the following raw materials by mass percentage:

3. The phosphate binder modified by tetrasodium iminodisuccinate according to claim 1, characterized in that: The mass percentage of the industrial phosphoric acid is 85%.

4. The phosphate binder modified by tetrasodium iminodisuccinate according to claim 1, characterized in that: The boric acid, silicic acid, light magnesium oxide and copper oxide are all of analytical grade.

5. The phosphate binder modified by tetrasodium iminodisuccinate according to claim 1, characterized in that: The tetrasodium iminodisuccinate is a colorless to light yellow aqueous solution with an effective content of 33%-35%.

6. A method for preparing a phosphate binder modified by tetrasodium iminodisuccinate according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Add industrial phosphoric acid into a reaction kettle and heat to 180-200°C while stirring; (2) adding aluminum hydroxide powder to the reaction kettle of step (1) above, and continuing to stir until the reaction solution becomes transparent; (3) adding one quarter of the total amount of water to the reaction kettle in step (2), and heating and stirring until the temperature of the reaction solution returns to the temperature before adding water; (4) Adding boric acid to the reaction kettle of step (3) above, and continuing to heat and stir until the reaction solution becomes transparent; (5) adding silicic acid to the reaction kettle of step (4) above, and continuing heating and stirring until the reaction solution becomes transparent; (6) adding one quarter of the total amount of water to the reaction kettle in step (5), and heating and stirring until the temperature of the reaction solution returns to the temperature before adding water; (7) Adding light magnesium oxide to the reaction kettle of step (6) above, and continuing to heat and stir until the reaction solution becomes transparent; (8) Add copper oxide to the reaction kettle of step (7) above, and continue heating and stirring until the reaction solution becomes transparent; (9) adding one quarter of the total amount of water to the reaction kettle in step (8), and heating and stirring until the temperature of the reaction solution returns to the temperature before adding water; (10) adding tetrasodium iminodisuccinate to the reaction kettle of step (9) above, and continuing heating and stirring until the reaction solution becomes transparent; (11) Add the remaining water of the total water volume to the reaction kettle of the above step (10), continue heating and stirring until the reaction solution is transparent and clear, remove the bottom precipitate after discharging the material, and obtain the phosphate binder modified by tetrasodium iminodisuccinate.

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