A flexible thin-layer two-component spraying material for mining and a preparation method thereof

Abstract

This invention belongs to the field of mine roadway support technology, specifically relating to a flexible thin-layer two-component spraying material for mining and its preparation method. The flexible thin-layer two-component spraying material of this invention includes component A and component B; component A includes EVA emulsion and film-forming aid; component B includes the following components in parts by weight: 20-40 parts melamine-modified urea-formaldehyde resin powder, 5-10 parts curing agent, 40-70 parts coal gasification slag, 3-7 parts expanded graphite, 3-5 parts α-zirconium phosphate, 1-2 parts coupling agent, and 0.05-0.3 parts fiber. The flexible thin-layer spraying material of this invention has low resilience, good adhesion, and helps inhibit crack propagation.

Description

Technical Field

[0001] This invention belongs to the field of mine roadway support technology, specifically relating to a flexible thin-layer two-component spraying material for mining and its preparation method. Background Technology

[0002] Currently, coal remains my country's primary energy source. With increasing energy demand, coal mining must grow accordingly, and mine safety is its fundamental guarantee. Loose and fractured areas exist in the roof of excavated roadways, where surface rock is highly susceptible to detachment, posing significant safety hazards. Furthermore, as the main channels for gas extraction, cracks in the roof of coal mine roadways simultaneously constitute critical pathways for gas and air leakage; these cracks will further exacerbate the risk of further cracking under long-term weathering.

[0003] Traditional mine roadway support primarily relies on anchor-mesh-shotcrete systems, with shotcrete widely used as a crucial sealing and support material. However, in practical engineering, especially in large-section roadways with complex geological conditions and intense mine pressure activity, traditional shotcrete support methods suffer from numerous inherent drawbacks, including difficult transportation, large quantities required, poor toughness, and slow setting. During actual use, the shotcrete layer may crack due to insufficient tensile strength, necessitating frequent maintenance. This maintenance not only increases the safety risk of structural instability but also severely impacts construction progress. Based on the shortcomings of traditional shotcrete, thin-layer sprayed materials have been widely used as a new type of material in recent years, but they still suffer from drawbacks such as high rebound rate and poor adhesion.

[0004] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible thin-film two-component spray coating material for mining and its preparation method, so as to help solve or improve at least one of the problems of high resilience, poor adhesion and easy cracking of current thin-film spray coating materials.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a flexible thin-layer two-component spraying material for mining, the flexible thin-layer two-component spraying material for mining includes component A and component B; component A includes EVA emulsion and film-forming aid; component B includes the following components in parts by weight: 20-40 parts of melamine-modified urea-formaldehyde resin powder, 5-10 parts of curing agent, 40-70 parts of coal gasification slag, 3-7 parts of expanded graphite, 3-5 parts of α-zirconium phosphate, 1-2 parts of coupling agent, and 0.05-0.3 parts of fiber.

[0007] Preferably, the A material further includes a film-forming aid; the mass ratio of the film-forming aid to the EVA emulsion is (1-10):(90-99).

[0008] Preferably, the film-forming aid is decyl alcohol ester; the EVA emulsion is model BJ-707 with a solid content ≥40%.

[0009] Preferably, the curing agent is a mixture of sodium dihydrogen phosphate and ammonium chloride, with a mass ratio of sodium dihydrogen phosphate to ammonium chloride of 3:1.

[0010] Preferably, the expanded graphite can pass through an 80-mesh sieve; the coal gasification slag is a solid waste generated during the coal gasification process, and particles with a diameter greater than 0.3 mm are screened out.

[0011] Preferably, the fiber is basalt fiber, and the fiber length is 3-6 mm.

[0012] Preferably, the coupling agent is a silane coupling agent.

[0013] The present invention also provides a method for preparing the above-mentioned flexible thin-film two-component spray coating material for mining, which adopts the following technical solution: The method for preparing the above-mentioned flexible thin-film two-component spray coating material for mining includes the following steps: (1) mixing the components of the A material evenly to obtain the A material; mixing the components of the B material evenly to obtain the B material; (2) mixing equal masses of the A material and the B material evenly to obtain the flexible thin-film two-component spray coating material for mining.

[0014] Beneficial effects:

[0015] In the mining flexible thin-layer two-component spray material of this invention, melamine-modified urea-formaldehyde resin provides high bonding strength and hardness; while the flexible EVA emulsion, through the formation of an interpenetrating network structure, acts as a toughening agent, effectively absorbing stress and significantly improving the crack resistance and deformation resistance of the adhesive layer. Furthermore, EVA improves the rheological properties of the adhesive and its wetting and penetration into tunnel rocks, and enhances cohesion at the molecular level through hydrogen bonding, thereby comprehensively improving the tensile toughness and overall mechanical properties of the material. Simultaneously, the EVA emulsion can effectively reduce the release of free formaldehyde after the melamine-modified urea-formaldehyde resin cures through dilution and physical sealing, thus improving the safety of the material. Sodium dihydrogen phosphate in the curing agent serves three purposes: first, it acts as an acidic catalyst for the urea-formaldehyde resin; second, the phosphorus-oxygen double bond of phosphate reacts with the hydroxyl groups in the resin, thereby playing a cross-linking and curing role; and third, the generated phosphate ester has a flame-retardant effect, thus providing strength support for the cured body while adjusting the setting time. Meanwhile, the synergistic effect of ammonium chloride and EVA emulsion effectively reduces the content of free formaldehyde, bringing it to safety standards. The synergistic effect of expanded graphite (physical thermal insulation) and α-zirconium phosphate (catalytic carbonization) provides the material with good flame retardant properties. Ultimately, through multi-component synergy, the requirements for rapid film formation, good adhesion, tensile strength, and flame retardancy in mining thin-layer spray coatings are met.

[0016] The mining flexible thin-film two-component spray material of this invention fully utilizes the advantages of EVA emulsion in film formation and its good flexibility after film formation, so that the material obtained after mixing it with modified urea-formaldehyde resin powder possesses both toughness and rigidity. Furthermore, component A in the mining thin-film spray material of this invention can be stored for 3 months; the curing agent used in the mining flexible spray material of this invention allows the modified urea-formaldehyde resin to cure rapidly, thereby shortening the surface drying time to 20-30 minutes and the actual drying time to 1.5-2.5 hours, and the viscosity can be adjusted according to actual conditions. Moreover, the preparation method of the mining flexible thin-film two-component spray material of this invention is simple, with low requirements for production equipment and personnel, requiring fewer workers and reducing labor costs; and the entire construction process generates no waste and does not pollute the environment.

[0017] Compared with traditional shotcrete, the flexible thin-layer spraying material for mining of this invention has the advantages of convenient transportation, low dosage, thin spray layer, good toughness, good adhesion, and fast setting. Compared with current thin-layer spraying materials, the flexible thin-layer spraying material for mining of this invention has the advantages of low rebound rate and good adhesion. The good adhesion of EVA emulsion and melamine-modified urea-formaldehyde resin can "connect" loose and broken areas to reduce detachment, and its good toughness allows it to absorb some energy through plastic deformation during the initiation stage of rock microcracks, effectively inhibiting crack propagation. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0019] Figure 1 This is a flowchart illustrating the preparation process of a flexible thin-film spraying material for mining, provided in one embodiment of the present invention.

[0020] Figure 2 These are sample images of the flexible thin-film spray coating materials for mining prepared in Examples 1-4;

[0021] Figure 3 The diagram shows the bending condition of the finished product in each embodiment. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0023] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0024] This invention addresses at least one of the problems of high rebound rate, poor adhesion, and easy cracking in current thin-layer spraying materials by providing a flexible thin-layer two-component spraying material for mining.

[0025] The flexible thin-film two-component spraying material for mining applications according to embodiments of the present invention includes component A and component B; component A includes EVA emulsion; component B includes the following components in parts by weight: 20-40 parts of modified urea-formaldehyde resin powder (e.g., 20, 25, 30, 35, or 40 parts), 5-10 parts of curing agent (e.g., 5, 6, 7, 8, 9, or 10 parts), and 40-70 parts of coal gasification slag (e.g., 40, 45, 50, 55, or 60 parts). The composition includes: 3-7 parts (e.g., 3, 4, 5, 6, or 7 parts) of expanded graphite, 3-5 parts (e.g., 3, 3.5, 4, 4.5, or 5 parts) of zirconium phosphate, 1-2 parts (e.g., 1, 1.3, 1.6, 1.8, or 2 parts) of coupling agent, and 0.05-0.3 parts (e.g., 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3 parts) of fiber. The synergistic effect of expanded graphite and zirconium phosphate achieves flame retardancy by constructing a heat-insulating layer and promoting optimized carbonization. However, excessive amounts of either will affect the mechanical properties of the material, while insufficient amounts will not achieve the desired flame retardant effect. The coupling agent can improve the interfacial compatibility and bonding strength between the organic polymer matrix (EVA and melamine-modified urea-formaldehyde resin) and the inorganic filler (zirconium phosphate, expanded graphite, and coal gasification slag).

[0026] Compared to traditional shotcrete (which is 80-100mm thick), the flexible thin-layer spraying material for mining of this invention has advantages such as convenient transportation, low dosage, thin spray layer (3-5mm), good toughness, and good adhesion. Compared to current thin-layer spraying materials, the flexible thin-layer spraying material for mining of this invention has advantages such as high tensile strength, low rebound rate, and good adhesion. The good adhesion of EVA emulsion and modified urea-formaldehyde resin can "connect" loose and broken areas to reduce detachment, and its good toughness allows it to absorb some energy through plastic deformation during the initiation stage of rock microcracks, effectively inhibiting crack propagation.

[0027] In a preferred embodiment of the flexible thin-film two-component spray material for mining of the present invention, component A further includes a film-forming aid; the mass ratio of the film-forming aid to the EVA emulsion (707) is (1-10):(90-99) (e.g., 1:99, 3:97, 5:95, 7:93, 9:91 or 10:90).

[0028] In a preferred embodiment of the flexible thin-film two-component spray material for mining of the present invention, the film-forming aid is decyl alcohol ester; the EVA emulsion is model BJ-707 with a solid content ≥40%.

[0029] In a preferred embodiment of the flexible thin-film two-component spray coating material for mining of the present invention, the curing agent is a mixture of sodium dihydrogen phosphate (powder) and ammonium chloride (powder), with a mass ratio of sodium dihydrogen phosphate to ammonium chloride of 3:1. If the proportion of sodium dihydrogen phosphate is too high, the mixture will thicken too quickly, affecting construction; if the proportion of sodium dihydrogen phosphate is too low, the ratio with the melamine-modified urea-formaldehyde resin will be unbalanced, affecting the final curing effect.

[0030] In a preferred embodiment of the flexible thin-film two-component spraying material for mining of the present invention, the expanded graphite can pass through an 80-mesh sieve; and the coal gasification slag can pass through a 0.3mm sieve.

[0031] In a preferred embodiment of the flexible thin-film two-component spray material for mining of the present invention, the fiber is basalt fiber, and the fiber length is 3-6 mm (e.g., 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm or 6 mm). Selecting a suitable fiber can alleviate the shrinkage and cracking phenomenon of the material. If the fiber is too long, it may cause serious agglomeration in the material and block the nozzle during actual use. If it is too short, it may not be able to exert its due anti-shrinkage and cracking performance.

[0032] In a preferred embodiment of the flexible thin-film two-component spray coating material for mining applications of the present invention, the coupling agent is a silane coupling agent. The EVA emulsion is an aqueous emulsion, and the hydrolysis process and hydrophilic / lipophilic balance of the silane coupling agent can help the aqueous polymer better wet and encapsulate the inorganic filler.

[0033] Preferably, the silane coupling agent is KH770.

[0034] This invention also proposes a method for preparing the above-mentioned flexible thin-film two-component spray coating material for mining. The method for preparing the flexible thin-film two-component spray coating material for mining in this embodiment includes the following steps: (1) mixing the components of material A evenly to obtain material A; mixing the components of material B evenly to obtain material B; (2) mixing equal masses of material A and material B evenly to obtain the flexible thin-film two-component spray coating material for mining. The flowchart of the method for preparing the flexible thin-film two-component spray coating material for mining in Embodiment 1 of this invention can be referred to. Figure 1 .

[0035] The following detailed description of the mining flexible thin-film two-component spray coating material and its preparation method of the present invention is provided through specific embodiments.

[0036] The main raw materials used in the following examples are: coal gasification slag with a particle size of less than 0.3 mm; expanded graphite that can pass through an 80-mesh sieve; basalt fiber with a length of 3-6 mm; and the main parameters of EVA emulsion (707) are shown in Table 1 below.

[0037] Table 1

[0038]

[0039] Example 1

[0040] The flexible thin-film two-component spraying material for mining in this embodiment includes:

[0041] Material A: Composed of 95 parts EVA emulsion (707) and 5 parts dodecyl alcohol ester;

[0042] Material B is a mixture of 20 parts melamine-modified urea-formaldehyde resin powder, 5 parts curing agent (a mixture of sodium dihydrogen phosphate and ammonium chloride in a mass ratio of 3:1), 5 parts expanded graphite, 1 part silane coupling agent (KH570), 64.85 parts coal gasification slag, 0.15 parts basalt fiber, and 4 parts α-zirconium phosphate.

[0043] The preparation method of the flexible thin-film two-component spray coating material for mining in this embodiment includes the following steps:

[0044] (1) Pour EVA emulsion (707) and alcohol ester twelve into a mixing pot and stir for 5 minutes to obtain material A; add modified urea-formaldehyde resin powder, curing agent, expanded graphite, silane coupling agent (KH570), coal gasification slag, α-zirconium phosphate and basalt fiber into the mixing pot in sequence and stir for 10 minutes to obtain material B. Note that the fiber can be added in the middle or last order, avoiding adding it first, to ensure that the fiber can be evenly distributed during the stirring process;

[0045] (2) Take material A and material B respectively (the mass ratio of material A and material B is 1:1), pour material B into material A and mix evenly to obtain the flexible thin-layer two-component spraying material for mining in this embodiment.

[0046] Example 2

[0047] The flexible thin-film two-component spraying material for mining in this embodiment includes:

[0048] Material A: Composed of 95 parts EVA emulsion (707) and 5 parts dodecyl alcohol ester;

[0049] Material B is a mixture of 25 parts melamine-modified urea-formaldehyde modified resin powder, 6.25 parts curing agent (a mixture of sodium dihydrogen phosphate and ammonium chloride in a mass ratio of 3:1), 5 parts expanded graphite, 1 part silane coupling agent (KH570), 58.5 parts coal gasification slag, 0.25 parts basalt fiber, and 4 parts α-zirconium phosphate.

[0050] The preparation method of the flexible thin-film two-component spray coating material for mining in this embodiment is the same as that in Example 1.

[0051] Example 3

[0052] The flexible thin-film two-component spraying material for mining in this embodiment includes:

[0053] Material A: Composed of 95 parts EVA emulsion (707) and 5 parts dodecyl alcohol ester;

[0054] Material B is a mixture of 30 parts melamine-modified urea-formaldehyde resin powder, 7.5 parts curing agent (a mixture of sodium dihydrogen phosphate and ammonium chloride in a mass ratio of 3:1), 5 parts expanded graphite, 1.5 parts silane coupling agent (KH570), 51.75 parts coal gasification slag, 0.25 parts basalt fiber, and 4 parts α-zirconium phosphate.

[0055] The preparation method of the flexible thin-film two-component spray coating material for mining in this embodiment is the same as that in Example 1.

[0056] Example 4

[0057] The flexible thin-film two-component spraying material for mining in this embodiment includes:

[0058] Material A: Composed of 95 parts EVA emulsion (707) and 5 parts dodecyl alcohol ester;

[0059] Material B is a mixture of 35 parts melamine-modified urea-formaldehyde resin powder, 8.75 parts curing agent (a mixture of sodium dihydrogen phosphate and ammonium chloride in a mass ratio of 3:1), 5 parts expanded graphite, 1.5 parts silane coupling agent (KH570), 45.5 parts coal gasification slag, 0.25 parts basalt fiber, and 4 parts α-zirconium phosphate.

[0060] The preparation method of the flexible thin-film two-component spray coating material for mining in this embodiment is the same as that in Example 1.

[0061] Example 5

[0062] The flexible thin-film two-component spraying material for mining in this embodiment includes:

[0063] Material A: Composed of 91 parts EVA emulsion (707) and 9 parts dodecyl alcohol ester;

[0064] Material B is a mixture of 35 parts melamine-modified urea-formaldehyde resin powder, 8.75 parts curing agent (a mixture of sodium dihydrogen phosphate and ammonium chloride in a mass ratio of 3:1), 5 parts expanded graphite, 1.5 parts silane coupling agent (KH570), 45.5 parts coal gasification slag, 0.25 parts basalt fiber, and 4 parts α-zirconium phosphate.

[0065] The preparation method of the flexible thin-film two-component spray coating material for mining in this embodiment is the same as that in Example 1.

[0066] Example 6

[0067] The only difference between this embodiment and embodiment 4 is that material A is composed of 90 parts of EVA emulsion (707) and 10 parts of alcohol ester twelve; the rest are the same as in embodiment 4.

[0068] The preparation method of the flexible thin-film two-component spraying material for mining in this embodiment is the same as that in Example 4.

[0069] Comparative Example 1

[0070] The only difference between this comparative example and Example 4 is that material A is composed of 85 parts of EVA emulsion (707) and 15 parts of alcohol ester twelve; the rest are the same as in Example 4.

[0071] The preparation method of the flexible thin-film two-component spray coating material for mining in this comparative example is the same as that in Example 4.

[0072] Comparative Example 2

[0073] The only difference between this comparative example and Example 4 is that material A is a mixture of 80 parts of EVA emulsion (707) and 20 parts of alcohol ester twelve; the rest are the same as in Example 4.

[0074] The preparation method of the flexible thin-film two-component spray coating material for mining in this comparative example is the same as that in Example 4.

[0075] Comparative Example 3

[0076] The only difference between this comparative example and Example 4 is that the alcohol ester twelve in material A is replaced with water; all other aspects are the same as in Example 4.

[0077] The preparation method of the flexible thin-film two-component spray coating material for mining in this comparative example is the same as that in Example 4.

[0078] Comparative Example 4

[0079] The only difference between this comparative example and Example 4 is that the melamine-modified urea-formaldehyde resin powder in material B is omitted; all other aspects are consistent with Example 4.

[0080] Comparative Example 5

[0081] The only difference between this comparative example and Example 4 is that the melamine-modified urea-formaldehyde resin powder in material B is replaced with unmodified urea-formaldehyde resin powder; all other aspects are the same as in Example 4.

[0082] Comparative Example 6

[0083] The only difference between this comparative example and Example 4 is that the amount of melamine-modified urea-formaldehyde resin powder in material B is 10 parts; all other aspects are the same as in Example 4.

[0084] Comparative Example 7

[0085] The only difference between this comparative example and Example 4 is that the amount of melamine-modified urea-formaldehyde resin powder in material B is 50 parts; all other aspects are the same as in Example 4.

[0086] Comparative Example 8

[0087] The only difference between this comparative example and Example 4 is that the sodium dihydrogen phosphate in the curing agent is replaced with an equal amount of ammonium chloride; all other aspects are the same as in Example 4.

[0088] Comparative Example 9

[0089] The only difference between this comparative example and Example 4 is that the ammonium chloride in the curing agent is replaced with an equal amount of sodium dihydrogen phosphate; all other aspects are the same as in Example 4.

[0090] Comparative Example 10

[0091] The only difference between this comparative example and Example 4 is that the mass ratio of sodium dihydrogen phosphate to ammonium chloride in the curing agent is 2:1; all other aspects are the same as in Example 4.

[0092] Comparative Example 11

[0093] The only difference between this comparative example and Example 4 is that the mass ratio of sodium dihydrogen phosphate to ammonium chloride in the curing agent is 4:1; all other aspects are the same as in Example 4.

[0094] Comparative Example 12

[0095] The only difference between this comparative example and Example 4 is that the sodium dihydrogen phosphate in the curing agent is replaced with an equal amount of sodium hydrogen phosphate; all other aspects are the same as in Example 4.

[0096] Comparative Example 13

[0097] The only difference between this comparative example and Example 4 is that the silane coupling agent (KH570) is omitted; all other aspects are the same as in Example 4.

[0098] Comparative Example 14

[0099] The only difference between this comparative example and Example 4 is that the coal gasification slag is replaced with natural sand with a particle size of less than 0.3 mm; all other aspects are the same as in Example 4.

[0100] Experimental Example

[0101] 1. Some sample images after demolding in Examples 1-5 are shown below. Figure 2 As shown; the bending conditions of each embodiment are not significantly different from those of the comparative example. Figure 3 As shown;

[0102] Depend on Figure 2 It can be seen that a flexible thin-film two-component spray coating material for mining with good film-forming properties and a smooth surface was prepared under the synergistic effect of each component.

[0103] Depend on Figure 3 It can be seen that the mixture of EVA emulsion and modified urea-formaldehyde resin powder can prepare a flexible thin-film two-component spray coating material with good toughness for mining. The performance of both can be fully utilized by appropriate ratio.

[0104] 2. The setting time, bond strength, compressive strength, tensile strength, elongation at break, and flame retardant properties of the flexible thin-film two-component spray coating material for mining described in the above embodiments were tested. The test results are shown in Table 3 below:

[0105] Test methods

[0106] Setting time: After evenly spreading the mixed material within the film frame, place it in the curing chamber to begin curing. Record the time from this point onwards, observing every 10 minutes. When a distinct thin film is observed on the sample surface, shorten the observation time, observing continuously for short periods. When the film appears denser after two observations, record the time t1 as the surface drying time. A similar method can be used to test the material's actual drying time. When the coating surface is dry with no free water and the structure has a certain strength, record the time t2 as the actual drying time.

[0107] Bond strength:

[0108] First, prepare (70×70×20) mm 3 After curing, the cement mortar test blocks are cleaned of surface impurities and laitance. The mixed coating is then applied to the cement mortar test blocks, maintaining a coating thickness of approximately 1.5 mm. The surface is smoothed, and the blocks are cured according to the coating curing conditions. The resulting specimens are then used for bonding strength testing. The specimens are installed on machine fixtures according to the national standard GB / T16777-2008, and their bonding strength is tested. The tensile speed is maintained at (5±1) mm / min, and the maximum tensile load F is recorded.

[0109] Bond strength is calculated using the following formula:

[0110] Δ=F / 1600

[0111] Where: Δ: bond strength (MPa);

[0112] F: Maximum tensile load (N).

[0113] Tensile strength and elongation at break

[0114] Pour the mixed thin-layer spray coating slurry into the Type I dumbbell-shaped specimen mold specified in GB / T 528-1998, and demold after curing to the test age. Adjust the machine clamps to maintain a spacing of 70 mm, place the specimen on the clamps, keeping its longitudinal direction aligned with the center line of the testing machine clamps, and then perform tensile testing at the standard specified speed. Record the data P displayed on the instrument, and measure the distance L1 between two adjacent marks at the point of fracture, accurate to 0.1 mm.

[0115] The tensile strength is calculated according to the following formula:

[0116] T = P / (B × D)

[0117] Where: T: tensile strength (MPa), accurate to 0.01 MPa;

[0118] P: Maximum tensile force (N);

[0119] B: Width of the middle part of the specimen (mm);

[0120] D: Specimen thickness (mm);

[0121] Elongation at break is calculated using the following formula:

[0122] E = (L1 - L0) / L0 × 100;

[0123] Where: E: elongation at break (%);

[0124] L0 is 25mm;

[0125] L1: Spacing between markings after specimen fracture (mm).

[0126] Flame retardant test

[0127] Combustion experiment using an alcohol torch: Use a clamp to hold a portion of the cured sample and place it in the flame of an alcohol torch for 30 seconds, then observe whether the sample burns.

[0128] Table 2

[0129]

[0130] The test results are shown in Table 3 below:

[0131] Table 3

[0132]

[0133] It can be seen from Table 3 above:

[0134] Examples 1-4 show that the bonding strength and tensile strength of the materials gradually increase with increasing melamine-modified urea-formaldehyde resin powder content, while the elongation at break gradually decreases, and the free formaldehyde content slightly increases. This indicates that under the action of sodium dihydrogen phosphate, the reactants of the melamine-modified urea-formaldehyde resin are the main support for the bonding strength and tensile strength. Simultaneously, due to the increase in the strength of the cured body, the elongation at break gradually decreases, but the decrease is very small. With the EVA emulsion remaining constant, although the free formaldehyde content slightly increases with increasing melamine-modified urea-formaldehyde resin powder content, it remains within the safe standard range, indicating that the curing agent has the function of curing the resin and consuming formaldehyde.

[0135] Examples 4-6 show that as the amount of EVA emulsion in material A increases and the amount of 12-ol ester decreases, the curing time does not change much, the bond strength and tensile strength gradually decrease, the elongation at break also shows a decreasing trend, the free formaldehyde content increases slightly, and the resilience also increases slightly.

[0136] In Examples 6 and Comparative Examples 1-2, after reducing the amount of EVA emulsion (707) by 5g, 10g, and 15g respectively compared to Example 4, the curing time gradually shortened, the bond strength, tensile strength, and elongation at break gradually decreased, while the free formaldehyde content and resilience gradually increased. This indicates that reducing the amount of EVA emulsion not only shortens the curing time, which is detrimental to construction, but also adversely affects the mechanical properties and elongation at break, while the free formaldehyde content and resilience gradually increase.

[0137] Compared to Example 4, Comparative Example 2, by replacing dodecyl alcohol ester with water, showed that, except for a slight increase in free formaldehyde content and a significant increase in resilience, other performance indicators of the material were significantly reduced, manifested as prolonged curing time and a significant decrease in bond strength, tensile strength, and elongation at break. This indicates that the addition of dodecyl alcohol ester can fully utilize the performance of EVA emulsion (707).

[0138] Comparative Example 4, which omits melamine-modified urea-formaldehyde resin powder in component B compared to Example 4, shows a significantly longer curing time, significantly reduced bond strength, tensile strength, and elongation at break, and an increased resilience, except that the free formaldehyde content is 0. This indicates that melamine-modified urea-formaldehyde resin powder has a significant impact on the curing speed and strength of the cured body.

[0139] Compared with Example 4, Comparative Example 5 replaced the melamine-modified urea-formaldehyde resin powder in material B with unmodified urea-formaldehyde resin powder. Although the effect on curing time and elongation at break was minimal, the bond strength and tensile strength decreased by 31% and 28.6% respectively, and the free formaldehyde content and resilience also increased significantly, indicating that the melamine-modified urea-formaldehyde resin powder was more effective.

[0140] The difference between Comparative Example 6 and Example 4 is that the amount of melamine-modified urea-formaldehyde resin powder in component B was reduced to 10 parts. Although the free formaldehyde content was reduced, the curing time was significantly prolonged, and the bonding strength and tensile strength decreased by 24.1% and 34.3%, respectively. This indicates that the reduction of modified urea-formaldehyde resin powder had an adverse effect on both curing time and mechanical properties.

[0141] The difference between Comparative Example 7 and Example 4 is that the amount of melamine-modified urea-formaldehyde resin powder was increased to 50 parts. The curing time was significantly shortened, and an excessively short curing time would affect the construction process. The bond strength, tensile strength, and elongation at break decreased slightly, by 13.8%, 8.6%, and 15.4%, respectively, indicating that excessive melamine-modified urea-formaldehyde resin powder does not have a beneficial effect on mechanical properties and elongation at break. The free formaldehyde content increased significantly. These findings demonstrate that excessive use of melamine-modified urea-formaldehyde resin powder does not have a beneficial effect on the system.

[0142] The difference between Comparative Example 8 and Example 4 is that an equal amount of sodium dihydrogen phosphate in the curing agent was replaced with ammonium chloride. First, the curing time was significantly extended, with the surface drying time increasing from 22 min to 55 min and the actual drying time increasing from 1.8 h to 3.8 h. Second, the bond strength and tensile strength were significantly reduced, decreasing by 55.2% and 60%, respectively. Third, the free formaldehyde content increased from 0.002% to 0.008%. In addition, the resilience rate also increased from 0.6% to 0.9%.

[0143] The difference between Comparative Example 9 and Example 4 is that the ammonium chloride in the curing agent was replaced with an equal amount of sodium dihydrogen phosphate. First, the curing time was significantly shortened, and an excessively short curing time would have an adverse effect on the construction. Second, the excessively fast curing time also had an adverse effect on the bonding strength, reducing it by 20.7%. Third, the free formaldehyde content increased significantly, from 0.002% to 0.019%. In addition, the rebound rate also increased significantly.

[0144] The difference between Comparative Example 10 and Example 4 is that the mass ratio of sodium dihydrogen phosphate to ammonium chloride in the curing agent was adjusted to 2:1. First, the surface drying time was extended from 22 min to 33 min, and the actual drying time was extended from 1.8 h to 2.8 h. Second, the bond strength, tensile strength, and elongation at break were reduced by 13.8%, 14.3%, and 19.2%, respectively. Third, the effect on free formaldehyde content and resilience was relatively small.

[0145] The difference between Comparative Example 11 and Example 4 is that the mass ratio of sodium dihydrogen phosphate to ammonium chloride in the curing agent was adjusted to 4:1. First, the curing time was shortened, with the surface drying time reduced by 13.6% and the actual drying time reduced by 11.1%. Second, the bond strength and tensile strength decreased by 13.8% and 11.4%, respectively. Third, the free formaldehyde content increased significantly from 0.002% to 0.008%. In addition, the effects on elongation at break and resilience were relatively small.

[0146] The difference between Comparative Example 12 and Example 4 is that sodium dihydrogen phosphate in the curing agent was replaced with an equal amount of sodium hydrogen phosphate. First, the curing time was significantly extended, with the surface drying time and the actual drying time extended by 17 min and 1.3 h, respectively. Second, the bond strength, tensile strength, and elongation at break decreased by 34.5%, 28.6%, and 11.5%, respectively. Third, the free formaldehyde content increased significantly from 0.002% to 0.007%. In addition, the resilience also increased from 0.6% to 1.2%.

[0147] The only difference between Comparative Example 13 and Example 4 is the omission of the silane coupling agent (KH570). The curing time was not affected. The bond strength and tensile strength decreased by 10.3% and 11.4% respectively, the elongation at break decreased by 19.2%, and the resilience increased from 0.6% to 0.9%. This indicates that the silane coupling agent makes the organic and inorganic materials in the components more uniformly mixed, thus having a beneficial effect on the performance.

[0148] The difference between Comparative Example 14 and Example 4 is that the coal gasification slag was replaced with natural sand. Similarly, the curing time was not affected, but the bond strength and tensile strength decreased by 20.7% and 17.1%, respectively, the elongation at break decreased by 23.1%, the free formaldehyde content increased by 12.5%, and the resilience increased from 0.6% to 1.5%. This indicates that the coal gasification slag had a beneficial effect on the performance of the thin-layer spray coating material.

[0149] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flexible thin-layered two-component sprayable material for mining, characterized in that, The flexible thin-film two-component spraying material for mining includes component A and component B; The A material comprises EVA emulsion and film-forming aid; the mass ratio of the film-forming aid to the EVA emulsion is (1-10):(90-99); Material B comprises the following components in parts by weight: 20-40 parts of melamine-modified urea-formaldehyde resin powder, 5-10 parts of curing agent, 40-70 parts of coal gasification slag, 3-7 parts of expanded graphite, 3-5 parts of α-zirconium phosphate, 1-2 parts of coupling agent, and 0.05-0.3 parts of fiber. The curing agent is a mixture of sodium dihydrogen phosphate and ammonium chloride, with a mass ratio of sodium dihydrogen phosphate to ammonium chloride of 3:1; The mass ratio of material A to material B is 1:

1.

2. The flexible thin-film two-component spray coating material for mining as described in claim 1, characterized in that, The film-forming aid is alcohol ester dodecyl; The EVA emulsion is model BJ-707, with a solid content of ≥40%.

3. The flexible thin-film two-component spray coating material for mining as described in claim 1, characterized in that, The expanded graphite can pass through an 80-mesh sieve; The coal gasification slag is a solid waste generated during the coal gasification process, and particles with a diameter greater than 0.3 mm are screened out.

4. The flexible thin-film two-component spray coating material for mining as described in claim 1, characterized in that, The fiber is basalt fiber, and the fiber length is 3-6 mm.

5. The flexible thin-film two-component spray coating material for mining as described in claim 1, characterized in that, The coupling agent is a silane coupling agent.

6. The method for preparing the flexible thin-film two-component spray coating material for mining as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Mix the components of material A evenly to obtain material A; mix the components of material B evenly to obtain material B; (2) Mix equal amounts of material A and material B evenly to obtain the flexible thin-layer two-component spray coating material for mining.

Images