A method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam

Abstract

A method for improving soft polyurethane foam by preparing a flame retardant coating based on graphite tailings. The present invention belongs to the field of flame retardant technology, and specifically relates to a method for improving soft polyurethane foam by preparing a flame retardant coating based on graphite tailings. The present invention aims to solve the problem of idle graphite tailings resources and the problem of reduced mechanical properties of foam and even cell collapse caused by existing physical and mechanical blending additive flame retardants. Method: 1. Heat-treating the graphite tailings raw material; 2. Mixing sodium alginate and pretreated graphite tailings, adding water to the mixed powder for wet ball milling; 3. First immersing the soft polyurethane foam in the mixed solution, and then immersing it in a calcium chloride solution; 4. Drying, waiting for its surface to solidify, and completing the preparation. The material prepared by the present invention has excellent flame retardant, mechanical and other properties, and is widely used; at the same time, it improves the comprehensive utilization rate of graphite tailings, reduces environmental pollution caused by graphite tailings, and also broadens the application range of soft polyurethane foam.

Description

Technical Field

[0001] The present invention belongs to the field of flame retardant technology, and in particular relates to a method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam. Background Art

[0002] my country is one of the world's largest graphite producers. Graphite tailings are solid waste generated during the graphite production process. Statistics show that in recent years, the total stockpile of graphite tailings in my country has exceeded 100 million tons. Furthermore, due to development needs, the global demand for graphite resources has increased significantly. As a byproduct of the graphite beneficiation process, the production of graphite tailings is also expected to increase annually. Currently, the most common method of treating graphite tailings in my country is to establish tailings ponds for storage. This method not only wastes a large amount of land but also causes significant pollution to the surrounding environment. Currently, most graphite tailings have not been comprehensively reused, leaving a large amount of available graphite tailings resources idle. There is an urgent need to vigorously develop research on the resource reuse of graphite tailings.

[0003] Flexible polyurethane foam has the advantages of low thermal conductivity, low density, and low cost, and is widely used in furniture, insulation, and packaging materials. However, due to its high flammability caused by its structure, it produces large amounts of toxic gases during combustion. Furthermore, the substrate can collapse on a large scale during combustion, seriously endangering human life and property safety. This also limits the application of flexible polyurethane foam in many fields.

[0004] There are two main methods for preparing soft flame-retardant polyurethane foam. One is reactive flame retardancy, in which the polyol in the raw materials for preparing soft polyurethane foam is modified to have flame-retardant elements. A dense carbon layer is directly formed during the combustion process to achieve a better flame retardant effect. However, this method has many practical application problems such as high price, complicated process, and difficult processing, and is not suitable for large-scale production. The other is additive flame retardancy, which is currently the most commonly used method in the preparation of soft flame-retardant polyurethane. Generally, additive flame retardants are introduced into the soft polyurethane matrix through simple physical and mechanical blending. The whole process does not involve chemical changes, but it will affect the foaming process of the foam, resulting in a decrease in the mechanical properties of the foam or even bubble collapse. Summary of the Invention

[0005] The present invention aims to solve the problem of idle graphite tailings resources and the problem that existing physical and mechanical blending additive flame retardants lead to decreased foam mechanical properties and even cell collapse, and provides a method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam.

[0006] A method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam is specifically carried out in the following steps:

[0007] 1. Heat-treating the graphite tailings raw materials to obtain treated graphite tailings;

[0008] 2. Mixing sodium alginate and pretreated graphite tailings to obtain a mixed powder; adding water to the mixed powder for wet ball milling to obtain a mixed solution;

[0009] 3. Immersing the soft polyurethane foam in the mixed solution and then in the calcium chloride solution to obtain a coated soft polyurethane foam;

[0010] Fourth, the coated soft polyurethane foam is dried, and after its surface is solidified, a soft polyurethane foam with a flame retardant coating prepared based on graphite tailings is obtained.

[0011] Beneficial effects of the present invention:

[0012] 1. By using graphite tailings as the primary raw material, the flame-retardant polyurethane coating material of the present invention improves the recycling rate of graphite tailings waste and reduces environmental pollution caused by graphite tailings. Cone calorimeter testing of the flame-retardant polyurethane coating composite material of the present invention demonstrated a lower heat release rate and smoke emission. Furthermore, the flame retardant performance of the flame-retardant and ceramic-coated polyurethane composite material passed the UL-94 horizontal combustion HB rating test. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a physical picture of the sample prepared in Example 1;

[0014] Figure 2 This is a scanning electron microscope image of a sample prepared as a comparative example;

[0015] Figure 3 This is a scanning electron microscope image of the sample prepared in Example 1;

[0016] Figure 4 This is the Fourier transform infrared spectrum of the sample prepared in Example 1;

[0017] Figure 5 1 represents the comparative example, 2 represents the first example, 3 represents the second example, 4 represents the third example, 5 represents the fourth example, and 6 represents the fifth example. DETAILED DESCRIPTION

[0018] Specific embodiment 1: This embodiment is a method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam, which is specifically carried out in the following steps:

[0019] 1. Heat-treating the graphite tailings raw materials to obtain treated graphite tailings;

[0020] 2. Mixing sodium alginate and pretreated graphite tailings to obtain a mixed powder; adding water to the mixed powder for wet ball milling to obtain a mixed solution;

[0021] 3. Immersing the soft polyurethane foam in the mixed solution and then in the calcium chloride solution to obtain a coated soft polyurethane foam;

[0022] Fourth, the coated soft polyurethane foam is dried, and after its surface is solidified, a soft polyurethane foam with a flame retardant coating prepared based on graphite tailings is obtained.

[0023] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the heat treatment in step 1 is to heat the graphite tailings raw material in a muffle furnace at 500-600° C. for 0.5-1.5 h. Other steps are the same as specific embodiment 1.

[0024] Specific embodiment 3: This embodiment differs from specific embodiment 1 in that the process parameters of the wet ball milling in step 2 are: a rotation speed of 200 to 400 rpm, and a ball milling time of 1 to 3 hours. Other parameters are the same as those in specific embodiment 1.

[0025] Specific embodiment 4: This embodiment differs from specific embodiment 1 in that the mass ratio of the pretreated graphite tailings to sodium alginate in step 2 is 1:(0.11-0.25). Other aspects are the same as specific embodiment 1.

[0026] Specific embodiment 5: This embodiment differs from specific embodiment 1 in that the mass ratio of the mixed powder to water in step 2 is 1:(5-15). Other aspects are the same as specific embodiment 1.

[0027] Specific embodiment 6: This embodiment differs from specific embodiment 1 in that the immersion time in the mixed solution in step 3 is 0.5 to 10 minutes. Other aspects are the same as specific embodiment 1.

[0028] Specific embodiment 7: This embodiment differs from specific embodiment 1 in that the immersion time in the calcium chloride solution in step 3 is 0.5 to 10 minutes. Other aspects are the same as specific embodiment 1.

[0029] Specific embodiment 8: This embodiment differs from specific embodiment 1 in that the mass ratio of calcium chloride to water in the calcium chloride solution in step 3 is 1:(20-40). Other aspects are the same as specific embodiment 1.

[0030] Specific embodiment 9: This embodiment differs from specific embodiment 1 in that the soaking sequence in step 3 is repeated 3 to 5 times. Other aspects are the same as specific embodiment 1.

[0031] Specific embodiment 10: This embodiment differs from specific embodiment 1 in that the drying in step 4 is performed at 50-100° C. for 6-18 hours. Other aspects are the same as specific embodiment 1.

[0032] The effect of the present invention is verified by the following experiments:

[0033] Example 1: A method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam is specifically carried out in the following steps:

[0034] 1. The graphite tailings raw material is heat-treated in a muffle furnace at 600° C. for 0.5 h to obtain treated graphite tailings;

[0035] 2. Mix 0.21 g of sodium alginate and 3.29 g of pretreated graphite tailings to obtain a mixed powder; add 3.5 g of water to the mixed powder and wet-mill it. The specific parameters of the ball milling are: speed 300 rpm, ball milling time 3 h, and finally obtain a mixed solution;

[0036] 3. Immersing the soft polyurethane foam in the mixed solution for 5 minutes, and then immersing it in a 3% calcium chloride solution for 5 minutes to obtain a coated soft polyurethane foam;

[0037] 4. The coated soft polyurethane foam was dried at 80° C. for 12 hours, and after its surface solidified, a soft polyurethane foam with a flame retardant coating prepared based on graphite tailings was obtained.

[0038] Example 2: This example differs from Example 1 in that the soaking sequence in step 3 is repeated three times. Other aspects are the same as Example 1.

[0039] Example 3: This example differs from Example 1 in that the soaking sequence in step 3 is repeated 5 times. Other aspects are the same as Example 1.

[0040] Example 4: This example differs from Example 1 in that: in step 2, 0.175 g of sodium alginate and 3.325 g of pretreated graphite tailings are mixed; in step 3, the soaking sequence is repeated three times. Other differences are the same as in Example 1.

[0041] Example 5: This example differs from Example 1 in that: in step 2, 0.175 g of sodium alginate and 3.325 g of pretreated graphite tailings are mixed; and in step 3, the soaking sequence is repeated 5 times. Other aspects are the same as in Example 1.

[0042] Comparative Example: Pure flexible polyurethane foam without adding any substance.

[0043] The graphite tailings described in Examples 1 to 5 are all from Luobei County, Hegang City, Heilongjiang Province. The specific composition of the graphite tailings (mass percentage of each component) is as follows:

[0044]

[0045] Table 1 Specific composition of graphite tailings

[0046] The flame retardant properties of the comparative example and the example were tested, and the PHRR (peak heat release rate), THR (total heat release), SPR (smoke release rate), and TSP (total smoke generation) of the comparative example and the example were detected using a cone calorimeter (cone), and the ISO5660-1 standard was adopted for testing; the UL-94 horizontal burning test adopted GB / T2408-2021 to test the burning intensity.

[0047] The flame retardant performance test data of the comparative example and examples 1 to 5 are as follows:

[0048]

[0049] Table 2 Soft polyurethane foam coating performance test data

[0050] According to the test data in Table 2, the flame retardant flexible polyurethane foam coating prepared in the present invention exhibits strong flame retardancy and smoke suppression properties in the test, and reaches the HB grade of the UL-94 horizontal combustion test.

[0051] Figure 1 This is a physical picture of the sample after preparation;

[0052] Figure 2 This is a scanning electron microscope image of the comparative example, which shows that the surface of the comparative example is smooth and the pore structure is clear;

[0053] Figure 3 This is the scanning electron microscope image of Example 1. The surface of the treated polyurethane foam maintains a porous structure to a certain extent, but it can be observed that the surface is rough and loaded with other substances, indicating that the coating is successfully modified on the surface of the polyurethane foam.

[0054] Figure 4 This is the infrared spectrum of the coating sample. The spectrum is at 3450cm -1 The absorption peak of 1050cm is derived from the stretching vibration of the OH bond on the six-membered ring of the macromolecule calcium alginate generated by the reaction of sodium alginate and calcium chloride. -1 The absorption peak is the stretching vibration of CO, indicating that the reaction of calcium alginate gel in the coating is complete.

[0055] Figure 5The thermogravimetric analysis diagrams of the comparative example and the example. 1 is the comparative example, and 2 to 6 are examples one to five respectively. It can be observed that there is a two-step degradation process, which mainly comes from the degradation of the soft segment and hard segment of the polyurethane foam. However, compared with the comparative example, it can be observed that the degradation of the example takes precedence over the comparative example, which is mainly due to the loss of bound water in the coating, and is also a manifestation of the better flame retardancy of the example. Compared with the rapid degradation rate at both ends of the comparative example, the degradation rate of the example shows a slow two-stage degradation, indicating that the example has better thermal stability. In addition, the overall residue of the example is greatly improved compared with the comparative example. The higher residue indicates that the example has a certain degree of carbonization. At the same time, the carbonized carbon slag can be used as a heat barrier to effectively isolate heat and improve the flame retardant properties of the polyurethane foam.

Claims

1. A method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam, characterized in that The preparation method of the flexible polyurethane composite foam containing a flame retardant ceramic coating is specifically carried out in the following steps:

1. Heat-treating the graphite tailings raw materials to obtain treated graphite tailings; 2. Mixing sodium alginate and pretreated graphite tailings to obtain a mixed powder; adding water to the mixed powder for wet ball milling to obtain a mixed solution; 3. Immersing the soft polyurethane foam in the mixed solution and then in the calcium chloride solution to obtain a coated soft polyurethane foam; Fourth, the coated soft polyurethane foam is dried, and after its surface is solidified, a soft polyurethane foam with a flame retardant coating prepared based on graphite tailings is obtained.

2. A method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam according to claim 1, characterized in that The heat treatment in step 1 is to heat treat the graphite tailings raw material in a muffle furnace at 500-600° C. for 0.5-1.5 h.

3. The method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam according to claim 1, characterized in that The process parameters of the wet ball milling in step 2 are: a rotation speed of 200 to 400 revolutions per minute, and a ball milling time of 1 to 3 hours.

4. The method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam according to claim 1, characterized in that The mass ratio of the pretreated graphite tailings to sodium alginate in step 2 is 1:(0.11-0.25).

5. A method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam according to claim 4, characterized in that The mass ratio of the mixed powder to water in step 2 is 1:(5-15).

6. The method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam according to claim 1, characterized in that The immersion time in the mixed solution in step 3 is 0.5 to 10 minutes.

7. The method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam according to claim 6, characterized in that The immersion time in the calcium chloride solution in step 3 is 0.5 to 10 minutes.

8. The method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam according to claim 7, characterized in that The mass ratio of calcium chloride to water in the calcium chloride solution in step 3 is 1:(20-40).

9. The method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam according to claim 1, characterized in that Repeat the soaking sequence in step 3 3 to 5 times.

10. The method for preparing a flame retardant coating based on graphite tailings to improve the flame retardant properties of soft polyurethane foam according to claim 1, characterized in that The drying in step 4 is carried out at 50-100° C. for 6-18 hours.

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