Refractory polymer thin-spraying cement coating material as well as preparation process and application thereof

Abstract

The invention discloses a fire-resistant polymer thin-spraying cement coating material as well as a preparation process and application thereof. The material is prepared from the following raw materials in parts by weight: 15 to 25 parts of cement, 10 to 40 parts of modified ethylene-vinyl acetate copolymer emulsion, 8 to 25 parts of zinc borate, 5 to 22 parts of quartz powder, 7 to 20 parts of calcium carbonate powder, 0.5 to 1.5 parts of auxiliaries and 5 to 15 parts of water. According to the invention, not only is the compatibility between the organic polymer emulsion and the cement coating improved, but also the fire resistance of the polymer cement coating material is improved, so that the cement coating material prepared by the invention has good mechanical properties and fire resistance.

Description

Technical Field

[0001] This invention relates to the field of sprayed cement coating technology, specifically to a refractory polymer thin-film sprayed cement coating material and its preparation process and application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Shotcrete coatings have been widely used in underground engineering projects such as mine roadways and tunnels due to their ability to improve structural stability, extend service life, and enhance resistance to environmental factors such as humidity and temperature changes. Although shotcrete coatings play a role in supporting and protecting these structures, their adhesion is weak because the unevenness of the soil and rock surface makes it difficult for the coating to penetrate. Furthermore, shotcrete coatings have almost zero elongation at break and poor bending resistance, making them prone to peeling off from the soil and rock surface during construction, and the resulting cement coating layer is susceptible to sudden fracture under stress.

[0004] Polymer cement coatings, formed by incorporating organic polymers into cement coating materials, help overcome the aforementioned problems of sprayed cement coatings due to their excellent adhesion, durability, and workability. However, polymer cement coatings generally suffer from poor fire resistance and insufficient mechanical properties, limiting their application in high-fire-resistance environments. This is because: organic polymers generally have poor high-temperature resistance and are prone to decomposition at high temperatures, easily causing cracking in the cement coating structure. Secondly, insufficient compatibility between organic polymers and cement coating materials leads to decreased strength and durability, resulting in delamination, peeling, and other problems, which in turn degrade the mechanical properties of the cement coating structure. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a fire-resistant polymer thin-film cement coating material, its preparation process, and its application. This material not only improves the compatibility between organic polymers and cement coatings but also enhances the fire resistance of the polymer cement coating material, resulting in a cement coating material with both excellent mechanical and fire-resistant properties. Specifically, the technical solution of this invention is as follows.

[0006] First, this invention provides a refractory polymer thin-film cement coating material, the raw materials of which include the following components: 15-25 parts by weight of cement, 10-40 parts by weight of modified ethylene-vinyl acetate copolymer emulsion (modified EVA emulsion), 8-25 parts by weight of zinc borate, 5-22 parts by weight of quartz powder, 7-20 parts by weight of calcium carbonate powder, 0.5-1.5 parts by weight of additives, and 5-15 parts by weight of water. The modified ethylene-vinyl acetate copolymer emulsion is prepared by the following method: (1) The silane coupling agent is added to water and subjected to ultrasonic treatment to hydrolyze the siloxane group of the silane coupling agent to form silanol group Si(OH)3, thereby obtaining a modified solution.

[0007] (2) The modified liquid is gradually added to the ethylene-vinyl acetate copolymer emulsion (EVA emulsion), and then heated and kept warm under stirring conditions. After the reaction is completed, the modified ethylene-vinyl acetate copolymer emulsion is obtained.

[0008] Further, in step (1), the silane coupling agent includes at least one of the following: NH2(CH2)3Si(OC2H5)3, CH2CH(O)CH2O(CH2)3Si(OCH3)3, CH2=C(CH3)COO(CH2)3Si(OCH3)3, NH2(CH2)2NH(CH2)3Si(OCH3)3, NH2(CH2)2NH2(CH2)3SiCH3(OCH3)2, etc.

[0009] Furthermore, the modified ethylene-vinyl acetate copolymer emulsion is prepared by the following method: Further, in step (1), the mass ratio of the silane coupling agent to water is 1:7~12.

[0010] Further, in step (1), the ultrasonic treatment time is 20-30 min to promote the hydrolysis reaction of the silane coupling agent.

[0011] Further, in step (2), the modified liquid is 20-30% of the mass of the ethylene-vinyl acetate copolymer emulsion. Optionally, the concentration of the ethylene-vinyl acetate copolymer emulsion is 45-55 wt.%.

[0012] Furthermore, in step (2), the heating temperature is 40~60℃ and the heat preservation time is 2~4 hours.

[0013] Further, the calcium carbonate powder has a fineness of 80-150 mesh. Optionally, the additives include at least one of water-reducing agents, preservatives, and crack-resistant agents.

[0014] Secondly, the present invention provides a preparation process for the fire-resistant polymer thin-spray cement coating material, comprising the following steps: mixing the cement, modified ethylene-vinyl acetate copolymer emulsion, zinc borate, quartz powder, calcium carbonate powder, additives, and water, and stirring evenly to obtain the final product.

[0015] Finally, this invention provides the application of the fire-resistant polymer thin-film cement coating material in underground engineering projects such as mines and tunnels.

[0016] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: (1) The thin-spray cement coating material of the present invention uses a VAE emulsion modified with a silane coupling agent. Through its combination with zinc borate, it not only improves the compatibility between the VAE emulsion and the cement coating, but also enhances the fire resistance of the polymer cement coating material, giving the cement coating material prepared by the present invention both good mechanical and fire resistance properties. This is because the Si-O bonds introduced by the silane coupling agent into the vinyl acetate-ethylene unit of the VAE emulsion not only improve the compatibility between the organic polymer molecules in the emulsion and the cement coating matrix, but also improve the high-temperature resistance of the organic polymer. This is because the Si-O bonds have high bond energy and are more difficult to break. When these bonds encounter higher temperatures, they may transform into a more stable Si-O network, and then into the SiO2 glass phase, which not only helps improve the high-temperature resistance but also prevents further oxygen diffusion, avoiding rapid oxidative degradation of the material, thereby improving the fire resistance of the material.

[0017] (2) The thin-spray cement coating material of the present invention also effectively improves the flame retardant performance through the synergistic effect of the modified VAE emulsion and zinc borate. This is because: after the zinc borate decomposes at high temperature, it forms a borate glass layer, which can isolate oxygen and reduce heat transfer, while also releasing water vapor to dilute combustible gases and lower the combustion temperature. The modified VAE emulsion forms a polymer network in the cement coating, which forms a char layer at high temperature, which can prevent heat and oxygen transfer. At the same time, the polymer network formed by the modified VAE emulsion in the cement coating also helps to reduce cracking and peeling of the cement coating material at high temperature.

[0018] (3) The present invention found that adding zinc borate alone to cement coating materials can easily cause a decrease in mechanical strength. When zinc borate and modified VAE emulsion are added together to cement coating materials, the above problem is effectively overcome. This is because the modified VAE emulsion is in a state of adsorption on the surface of cement particles. As the cement particles gradually hydrate and consume free water, the modified VAE emulsion gradually loses water and forms an organic-inorganic composite network, which helps to improve the mechanical strength of the material. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, 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 improper limitation of the invention.

[0020] Figure 1 The image shows a sample of the modified ethylene-vinyl acetate copolymer emulsion prepared in Example 1 below.

[0021] Figure 2 The following are test results for tensile strength and elongation at break in Example 1.

[0022] Figure 3 The image shows a sample of the modified ethylene-vinyl acetate copolymer emulsion prepared in Example 2 below.

[0023] Figure 4 The image shows a sample of the modified ethylene-vinyl acetate copolymer emulsion prepared in Example 3 below.

[0024] Figure 5 The image shows a sample of the modified ethylene-vinyl acetate copolymer emulsion prepared in Example 4 below.

[0025] Figure 6 The image shows a sample of the modified ethylene-vinyl acetate copolymer emulsion prepared in Example 5 below.

[0026] Figure 7 The image shows a sample of the modified ethylene-vinyl acetate copolymer emulsion prepared in Example 6 below. Detailed Implementation

[0027] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0028] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. All reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions.

[0029] Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the method of this invention. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0030] Example 1: A preparation process for a refractory polymer thin-film cementitious coating material, comprising the following steps: (1) Mix silane-coupled KH-550 (NH2(CH2)3Si(OC2H5)3) with water at a mass ratio of 1:10 and then sonicate for 30 min to obtain a modified solution for later use.

[0031] (2) Slowly add 15% by mass of the modified solution to a 48 wt.% ethylene-vinyl acetate copolymer emulsion, and then heat in a water bath to 60°C for 2 hours under stirring. After completion, a modified ethylene-vinyl acetate copolymer emulsion (e.g.) is obtained. Figure 1 (As shown), for later use.

[0032] (3) Take the following raw material components in the following proportions: 25 parts by weight of 42.5 ordinary white silicate cement (WPC), 30 parts by weight of the modified ethylene-vinyl acetate copolymer emulsion described in this example, 17 parts by weight of zinc borate, 15 parts by weight of quartz powder, 9 parts by weight of calcium carbonate powder with a fineness of 80 mesh, 1 part by weight of polycarboxylate superplasticizer, and 10 parts by weight of water. Mix the above components and stir for 3 minutes to obtain the cement coating material.

[0033] Performance Testing: The test results of various performance indicators of the cement coating material prepared in this embodiment are shown in the table below, including the tensile strength and elongation at break tests. Figure 2 As shown:

[0034] Example 2: A preparation process for a refractory polymer thin-film cementitious coating material, comprising the following steps: (1) Mix silane-coupled KH-560 (CH2CH(O)CH2O(CH2)3Si(OCH3)3) with water at a mass ratio of 1:7 and then sonicate for 20 min to obtain a modified solution for later use.

[0035] (2) Slowly add 30% by weight of the modified solution to a 45 wt.% ethylene-vinyl acetate copolymer emulsion, and then heat in a water bath to 50°C for 3 hours under stirring. After completion, a modified ethylene-vinyl acetate copolymer emulsion (e.g.) is obtained. Figure 3 (As shown), for later use.

[0036] (3) Take the following raw material components in the following proportions: 20 parts by weight of 42.5 ordinary white silicate cement (WPC), 40 parts by weight of the modified ethylene-vinyl acetate copolymer emulsion described in this example, 25 parts by weight of zinc borate, 22 parts by weight of quartz powder, 20 parts by weight of calcium carbonate powder with a fineness of 100 mesh, 1.5 parts by weight of polycarboxylate superplasticizer, and 15 parts by weight of water. Mix the above components and stir for 3 minutes to obtain the cement coating material.

[0037] Performance Testing: The test results of various performance indicators of the cement coating material prepared in this embodiment are shown in the table below, including the bond strength test results:

[0038] Example 3: A preparation process for a refractory polymer thin-film cementitious coating material, comprising the following steps: (1) Mix silane-coupled A-174 (CH2=C(CH3)COO(CH2)3Si(OCH3)3) with water at a mass ratio of 1:12 and then sonicate for 25 min to obtain a modified solution for later use.

[0039] (2) Slowly add 20% by mass of the modified solution to a 55 wt.% ethylene-vinyl acetate copolymer emulsion, and then heat in a water bath to 40°C under stirring for 4 hours. After completion, a modified ethylene-vinyl acetate copolymer emulsion (e.g.) is obtained. Figure 4 (As shown), for later use.

[0040] (3) Take the following raw material components in the following proportions: 15 parts by weight of 42.5 ordinary white silicate cement (WPC), 10 parts by weight of the modified ethylene-vinyl acetate copolymer emulsion described in this example, 8 parts by weight of zinc borate, 5 parts by weight of quartz powder, 7 parts by weight of calcium carbonate powder with a fineness of 150 mesh, 0.5 parts by weight of polycarboxylate superplasticizer, and 5 parts by weight of water. Mix the above components and stir for 3 minutes to obtain the cement coating material.

[0041] Performance Testing: The test results of various performance indicators of the cement coating material prepared in this embodiment are shown in the table below, including the bond strength test results:

[0042] Example 4: A preparation process for a refractory polymer thin-film cementitious coating material, comprising the following steps: (1) Slowly add 15% (by weight) of water to a 48 wt.% ethylene-vinyl acetate copolymer emulsion, then heat in a water bath to 60°C under stirring and maintain the temperature for 2 hours. After completion, a modified ethylene-vinyl acetate copolymer emulsion (e.g.) is obtained. Figure 5 (As shown), for later use.

[0043] (2) Take the following raw material components in the following proportions: 25 parts by weight of 42.5 ordinary white silicate cement (WPC), 30 parts by weight of the modified ethylene-vinyl acetate copolymer emulsion described in this example, 17 parts by weight of zinc borate, 15 parts by weight of quartz powder, 9 parts by weight of calcium carbonate powder with a fineness of 80 mesh, 1 part by weight of polycarboxylate superplasticizer, and 10 parts by weight of water. Mix the above components and stir for 3 minutes to obtain the cement coating material.

[0044] Performance Testing: The test results of various performance indicators of the cement coating material prepared in this embodiment are shown in the table below, including the bond strength test results:

[0045] Example 5: A preparation process for a refractory polymer thin-film cementitious coating material, comprising the following steps: (1) Mix silane-coupled KH-560 (CH2CH(O)CH2O(CH2)3Si(OCH3)3) with water at a mass ratio of 1:7 and then sonicate for 20 min to obtain a modified solution for later use.

[0046] (2) Slowly add 30% by weight of the modified solution to a 45 wt.% ethylene-vinyl acetate copolymer emulsion, and then heat in a water bath to 50°C for 3 hours under stirring. After completion, a modified ethylene-vinyl acetate copolymer emulsion (e.g.) is obtained. Figure 6 (As shown), for later use.

[0047] (3) Take the following raw material components in the following proportions: 20 parts by weight of 42.5 ordinary white silicate cement (WPC), 40 parts by weight of the modified ethylene-vinyl acetate copolymer emulsion described in this example, 22 parts by weight of quartz powder, 20 parts by weight of calcium carbonate powder with a fineness of 100 mesh, 1.5 parts by weight of polycarboxylate superplasticizer, and 15 parts by weight of water. Mix the above components and stir for 3 minutes to obtain the cement coating material.

[0048] Performance Testing: The test results of various performance indicators of the cement coating material prepared in this embodiment are shown in the table below, including the bond strength test results:

[0049] Example 6: A preparation process for a refractory polymer thin-film cementitious coating material, comprising the following steps: (1) Mix silane-coupled A-174 (CH2=C(CH3)COO(CH2)3Si(OCH3)3) with water at a mass ratio of 1:12 and then sonicate for 25 min to obtain a modified solution for later use.

[0050] (2) Slowly add 20% by mass of the modified solution to a 55 wt.% ethylene-vinyl acetate copolymer emulsion, and stir until homogeneous to obtain a modified ethylene-vinyl acetate copolymer emulsion (e.g. Figure 7 (As shown), for later use.

[0051] (3) Take the following raw material components in the following proportions: 15 parts by weight of 42.5 ordinary white silicate cement (WPC), 10 parts by weight of the modified ethylene-vinyl acetate copolymer emulsion described in this example, 8 parts by weight of zinc borate, 5 parts by weight of quartz powder, 7 parts by weight of calcium carbonate powder with a fineness of 150 mesh, 0.5 parts by weight of polycarboxylate superplasticizer, and 5 parts by weight of water. Mix the above components and stir for 3 minutes to obtain the cement coating material.

[0052] Performance Testing: The test results of various performance indicators of the cement coating material prepared in this embodiment are shown in the table below, including the bond strength test results:

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A refractory polymer thin-film cementitious coating material, characterized in that, The product comprises the following components: 15-25 parts by weight of cement, 10-40 parts by weight of modified ethylene-vinyl acetate copolymer emulsion, 8-25 parts by weight of zinc borate, 5-22 parts by weight of quartz powder, 7-20 parts by weight of calcium carbonate powder, 0.5-1.5 parts by weight of additives, and 5-15 parts by weight of water; wherein the modified ethylene-vinyl acetate copolymer emulsion is prepared by the following method: (1) The silane coupling agent is added to water and subjected to ultrasonic treatment to hydrolyze the siloxane group of the silane coupling agent to form silanol group Si(OH)3, thereby obtaining a modified solution; (2) The modified liquid is gradually added to the ethylene-vinyl acetate copolymer emulsion, and then heated and kept warm under stirring conditions; after the reaction is completed, the modified ethylene-vinyl acetate copolymer emulsion is obtained.

2. The refractory polymer thin-film cementitious coating material according to claim 1, characterized in that, In step (1), the silane coupling agent includes at least one of the following: NH2(CH2)3Si(OC2H5)3, CH2CH(O)CH2O(CH2)3Si(OCH3)3, CH2=C(CH3)COO(CH2)3Si(OCH3)3, NH2(CH2)2NH(CH2)3Si(OCH3)3, and NH2(CH2)2NH2(CH2)3SiCH3(OCH3)2.

3. The refractory polymer thin-film cementitious coating material according to claim 1, characterized in that, In step (1), the mass ratio of the silane coupling agent to water is 1:7~12; optionally, in step (1), the ultrasonic treatment time is 20~30 min.

4. The refractory polymer thin-film cementitious coating material according to claim 1, characterized in that, In step (2), the modified liquid is 20-30% of the mass of the ethylene-vinyl acetate copolymer emulsion.

5. The refractory polymer thin-film cementitious coating material according to claim 1, characterized in that, In step (2), the concentration of the ethylene-vinyl acetate copolymer emulsion is 45~55 wt.%.

6. The refractory polymer thin-film cementitious coating material according to claim 1, characterized in that, In step (2), the heating temperature is 40~60℃ and the heat preservation time is 2~4 hours.

7. The preparation process of the refractory polymer thin-film cementitious coating material according to any one of claims 1-6, characterized in that, The process includes the following steps: mixing the cement, modified ethylene-vinyl acetate copolymer emulsion, zinc borate, quartz powder, calcium carbonate powder, additives, and water, and stirring until homogeneous to obtain the final product.

8. The refractory polymer thin-film cementitious coating material according to claim 7, characterized in that, The fineness of the calcium carbonate powder is 80~150 mesh.

9. The refractory polymer thin-film cementitious coating material according to claim 7 or 8, characterized in that, The additives include at least one of water-reducing agents, preservatives, and crack-resistant agents.

10. The application of the refractory polymer thin-film cementitious coating material according to any one of claims 1-6, or the refractory polymer thin-film cementitious coating material obtained by the preparation process according to any one of claims 7-9, in underground engineering; optionally, the underground engineering includes at least one of mines and tunnels.

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