High-breathability double-warp drying net

Abstract

The invention relates to a high-breathability double-warp drying net which comprises a drying net body and a breathable coating, and the breathable coating is formed by coating the surface of the drying net body with breathable paint. The breathable coating is prepared from the following components in parts by mass: 180 to 220 parts of polytetrafluoroethylene, 120 to 140 parts of an epoxy resin composite system, 120 to 160 parts of polypropylene, 10 to 12 parts of a flatting agent, 40 to 50 parts of a curing agent and 12 to 14 parts of a de-foaming agent, the epoxy resin composite system is prepared from the following raw materials: hydrophobic silicon dioxide, a silane coupling agent and epoxy resin. The air-permeable drying net has the effect of air permeability of the drying net.

Description

Technical Field

[0001] The present application relates to the field of drying nets, and in particular to a highly breathable double-warp drying net. Background Art

[0002] The papermaking drying fabric is an important dehydrating material in the drying section of the paper machine. Its main function is to remove excess moisture from the paper sheets. In the dryer section, more than 50% of the moisture of the paper sheets needs to be removed. At the same time, the drying fabric can also improve the quality of the finished paper.

[0003] With the rapid development of the papermaking industry, paper machines are running at faster and faster speeds, with wider and wider widths. The requirements for paper quality are constantly increasing, and the requirements for papermaking drying fabrics are getting higher and higher, especially in terms of paper surface quality, stability and service life.

[0004] Over long-term use, drying meshes are subject to the effects of high temperatures, humidity, and chemicals, causing the mesh material to age and deform, and the mesh structure to change, resulting in a gradual decline in air permeability. Furthermore, as use increases, dirt and impurities accumulate on the surface of the drying mesh, further affecting air permeability. Uneven air permeability can lead to uneven flow and distribution of the drying medium across the mesh surface, resulting in uneven heat and mass transfer during the drying process, leading to inconsistent quality of the dried product. Summary of the Invention

[0005] In order to solve the above problems, the present application provides a highly breathable double-warp drying net.

[0006] The present application provides a highly breathable double-warp drying net that adopts the following technical solution: A highly breathable double-warp drying net comprises a drying net body and a breathable coating, wherein the breathable coating is formed by coating the breathable coating on the surface of the drying net body, and the breathable coating comprises the following components in mass fractions: 180-220 parts of polytetrafluoroethylene, 120-140 parts of epoxy resin composite system, 120-160 parts of polypropylene, 10-12 parts of leveling agent, 40-50 parts of curing agent, and 12-14 parts of defoaming agent; The raw materials of the epoxy resin composite system include hydrophobic silica, a silane coupling agent and epoxy resin.

[0007] By adopting the above technical solution, after the breathable coating is coated on the surface of the double-warp drying mesh, a breathable coating is formed on the surface. Polytetrafluoroethylene is used as the base material. Polytetrafluoroethylene has good breathability, which can make the drying mesh have good breathability, thereby improving the drying performance of the drying mesh for the material. At the same time, polypropylene has low molecular gas permeation resistance and also has good breathability. The combination of the two can synergistically improve the overall breathability of the system. An epoxy resin composite system obtained by forming hydrophobic silica, silane coupling agent and epoxy resin is also added to the system, so that the breathable coating has good hydrophobic properties, thereby reducing the penetration of water into the coating gaps and playing a positive role in breathability. The hydrophobic silica is used as a filler and is treated with a silane coupling agent so that the hydrophobic silica is evenly distributed in the system, thereby improving the compatibility of the system and further improving the breathability. At the same time, the hydrophobic silica also has good corrosion resistance, thereby further improving the corrosion resistance and mechanical strength of the drying mesh.

[0008] Preferably, the epoxy resin composite system is prepared by the following method: After mixing hydrophobic silica, toluene and silane coupling agent, ultrasonically obtain a mixed system, add epoxy resin and sustained-release agent to the mixed system, heat and stir, add water and toluene, magnetically stir, then add maleimide, and magnetically stir to obtain an epoxy resin composite system.

[0009] By adopting the above technical solution, after adding hydrophobic silica to the epoxy resin, it cross-links with the epoxy resin to increase the cross-linking density of the epoxy resin, which can effectively reduce the cracking phenomenon of the system and improve the overall corrosion resistance of the system, thereby further improving the stability of the double-warp drying screen.

[0010] Preferably, the sustained-release agent comprises furfurylamine.

[0011] By adopting the above technical solution, the furan group of the sustained-release agent furfurylamine and the maleimide group of maleimide can react reversibly, so that the prepared coating has good self-healing properties, thereby making the breathable coating have good self-healing properties, playing a protective role on the double-warp drying mesh. At the same time, the amino group in furfurylamine can also form a cross-linking reaction with the epoxy resin, and the combined action with the hydrophobic silica blocks the penetration of corrosive media, thereby further improving the corrosion resistance of the double-warp drying mesh.

[0012] Preferably, the mass ratio of the epoxy resin, furfurylamine and maleimide is 4.2:(0.5-0.6):1.

[0013] By adopting the above technical solution, the mass ratio of the epoxy resin, furfurylamine and maleimide is preferably within the above range, which can further improve the overall stability of the prepared epoxy resin composite system.

[0014] Preferably, the mass fraction of the hydrophobic silica is 6-8% of the mass of the epoxy resin.

[0015] By adopting the above technical solution, preferably the mass fraction of the hydrophobic silica is within the above range, which can further improve the overall stability of the prepared epoxy resin composite system.

[0016] Preferably, the hydrophobic silica raw material includes a surfactant, copper chloride dihydrate, ethyl orthosilicate and sodium borohydride.

[0017] By adopting the above technical solution, the copper nanoparticles in copper chloride dihydrate are used as catalytic active sites, so that silica is fixed and dispersed as a carrier to improve the dispersibility of silica in the system. At the same time, it is further filled in the resin to improve the overall corrosion resistance and strength of the system.

[0018] Preferably, the hydrophobic silica is prepared by the following method: Copper chloride dihydrate, ethanol and ammonia water are mixed and ultrasonicated, and then stirred in an ice water bath to obtain a mixture. A surfactant is mixed with ethanol, and then mixed with the mixture prepared above. Then, ethyl orthosilicate is added. After stirring, sodium borohydride is added to react, and the mixture is washed and freeze-dried to obtain hydrophobic silica.

[0019] By adopting the above technical solution, after the Cu ions are reduced, copper nanoparticles are grown in situ to allow the silica and Cu to combine. The surfactant adjusts the particle size of the system in one step, so that the obtained hydrophobic silica has good filling stability.

[0020] Preferably, the surfactant comprises cetyltrimethylammonium bromide.

[0021] By adopting the above technical solution and using hexadecyltrimethylammonium bromide as a surfactant, the contact angle of silica can be further increased, thereby making the hydrophobic silica have good hydrophobic properties and further improving the activity of the system. The positive charge of hexadecyltrimethylammonium bromide interacts with Cu, thereby further improving the dispersibility of the prepared hydrophobic silica.

[0022] Preferably, the mass ratio of the copper chloride dihydrate, hexadecyltrimethylammonium bromide and tetraethyl orthosilicate is 1:(2.6-2.8):4.3.

[0023] By adopting the above technical solution, preferably the mass ratio of copper chloride dihydrate, hexadecyltrimethylammonium bromide and ethyl orthosilicate is within the above range, which can further improve the stability of the prepared hydrophobic silica.

[0024] Preferably, the breathable coating is prepared by the following method:.

[0025] In summary, this application includes at least one of the following beneficial technical effects: 1. After the breathable coating is applied to the surface of the drying mesh body, a breathable coating is formed on the surface of the drying mesh body. Polytetrafluoroethylene has good breathability, and the formed breathable coating has good breathability. The gas molecules of polypropylene have low permeation resistance and also have good breathability. The two can synergistically improve the overall breathability after being combined. The system also contains an epoxy resin composite system formed by hydrophobic silica, silane coupling agent and epoxy resin, which can reduce the penetration of water into the coating gap, thereby playing a good breathability role. At the same time, hydrophobic silica acts as a filler to improve the overall hydrophobicity and corrosion resistance of the system, so that the prepared highly breathable double-warp drying mesh has good stability and mechanical strength.

[0026] 2. The furan group in furfurylamine can reversibly react with the maleimide group in maleimide, giving the prepared breathable coating excellent self-healing properties. At the same time, the amino group in furfurylamine forms a cross-linking reaction with the epoxy resin scaffold, which synergistically blocks the penetration of corrosive media with the hydrophobic silica, further improving the overall corrosion resistance of the system. 3. Using Cu nanoparticles in copper chloride dihydrate as catalytic active sites, combined with hexadecyltrimethylammonium bromide, copper nanoparticles are grown in situ on the silica surface, further combining silica and Cu, and adjusting the particle size of the system, so that the prepared hydrophobic silica has good filling stability and effectively improves the dispersion performance of the hydrophobic silica. DETAILED DESCRIPTION

[0027] The present application is further described in detail below with reference to the embodiments: Raw materials: All raw materials in the examples are commercially available; the leveling agent is BYK-333; and the defoaming agent is oleic acid (CAS No.: 112-80-1).

[0028] Example 1 Preparation of hydrophobic silica: 7.59 g of copper chloride dihydrate, 240 g of ethanol, and 4.8 g of ammonia water were mixed and ultrasonicated for 10 minutes, and then stirred in an ice-water bath for 1 hour to obtain a mixture. 19.75 g of hexadecyltrimethylammonium bromide (CAS No.: 57-09-0) was mixed with 120 g of ethanol, and then mixed with the above-prepared mixture. 32.66 g of ethyl orthosilicate was added, and the mixture was stirred in an ice-water bath for 5 hours. Then, 60 g of 2.5 mg / ml of sodium borohydride was added and stirred for 12 hours. After washing alternately with anhydrous ethanol and deionized water, the mixture was freeze-dried at -20°C for 18 hours to obtain hydrophobic silica.

[0029] Preparation of epoxy resin composite system: After mixing hydrophobic silica, 400 g of toluene and 19 g of silane coupling agent, ultrasonically treated for 10 minutes to obtain a mixed system, 147.37 g of epoxy resin and 17.54 g of furfurylamine (CAS No.: 617-89-0) were added to the mixed system, the temperature was raised to 90°C, and magnetic stirring was carried out at a speed of 600 rpm for 30 minutes. Then, 12 g of deionized water and 120 g of toluene were added, and magnetic stirring was carried out at a speed of 1000 rpm for 10 minutes at 90°C. Finally, 35.09 g of maleimide (CAS No.: 541-59-3) was added, and magnetic stirring was carried out at 90°C for 10 minutes to obtain an epoxy resin composite system.

[0030] Preparation of breathable coating: 180 g of polytetrafluoroethylene (CAS No.: 9002-84-0), 120 g of epoxy resin composite system, 120 g of polypropylene, 10 g of leveling agent, 40 g of curing agent, and 12 g of defoaming agent were mixed, and stirred at a speed of 150 rpm for 20 minutes to obtain a breathable coating.

[0031] Preparation of highly breathable double-warp drying fabric: The drying net body is completely immersed in the breathable coating, left to stand for 40 minutes, then taken out and dried in an oven at 40°C for 4 hours to form a breathable coating on the surface of the drying net body, thereby obtaining a highly breathable double-warp drying net.

[0032] Example 2 Preparation of hydrophobic silica: 7.41 g of copper chloride dihydrate, 240 g of ethanol, and 4.8 g of ammonia water were mixed and ultrasonicated for 10 minutes, and then stirred in an ice-water bath for 1 hour to obtain a mixture. 20.74 g of hexadecyltrimethylammonium bromide was mixed with 120 g of ethanol, and then mixed with the above-prepared mixture. 31.85 g of ethyl orthosilicate was added, and the mixture was stirred in an ice-water bath for 5 hours. Then, 60 g of 2.5 mg / ml of sodium borohydride was added and stirred for 12 hours. After washing alternately with anhydrous ethanol and deionized water, the mixture was freeze-dried at -20°C for 18 hours to obtain hydrophobic silica.

[0033] Preparation of epoxy resin composite system: After mixing hydrophobic silica, 400 g of toluene and 19 g of silane coupling agent, ultrasonically treated for 10 minutes to obtain a mixed system, 144.83 g of epoxy resin and 20.69 g of furfurylamine were added to the mixed system, the temperature was raised to 90°C, and magnetic stirring was carried out at a speed of 600 rpm for 30 minutes. Then, 12 g of deionized water and 120 g of toluene were added, and magnetic stirring was carried out at a speed of 1000 rpm for 10 minutes at 90°C. Finally, 34.48 g of maleimide was added, and magnetic stirring was carried out at 90°C for 10 minutes to obtain an epoxy resin composite system.

[0034] Preparation of breathable coating: 220 g of polytetrafluoroethylene, 140 g of epoxy resin composite system, 160 g of polypropylene, 12 g of leveling agent, 50 g of curing agent, and 14 g of defoaming agent were mixed, and stirred at a speed of 150 rpm for 20 minutes to obtain a breathable coating.

[0035] Preparation of highly breathable double-warp drying fabric: The drying net body is completely immersed in the breathable coating, left to stand for 40 minutes, then taken out and dried in an oven at 40°C for 4 hours to form a breathable coating on the surface of the drying net body, thereby obtaining a highly breathable double-warp drying net.

[0036] Example 3 Preparation of hydrophobic silica: 7.5 g of copper chloride dihydrate, 240 g of ethanol, and 4.8 g of ammonia water were mixed and ultrasonicated for 10 minutes, and then stirred in an ice-water bath for 1 hour to obtain a mixture. 20.25 g of hexadecyltrimethylammonium bromide was mixed with 120 g of ethanol, and then mixed with the above-prepared mixture. 32.25 g of ethyl orthosilicate was added, and the mixture was stirred in an ice-water bath for 5 hours. Then, 60 g of 2.5 mg / ml of sodium borohydride was added and stirred for 12 hours. After washing alternately with anhydrous ethanol and deionized water, the mixture was freeze-dried at -20°C for 18 hours to obtain hydrophobic silica.

[0037] Preparation of epoxy resin composite system: After mixing hydrophobic silica, 400 g of toluene and 19 g of silane coupling agent, ultrasonically treated for 10 minutes to obtain a mixed system, 143.59 g of epoxy resin and 22.22 g of furfurylamine were added to the mixed system, the temperature was raised to 90°C, and magnetic stirring was carried out at a speed of 600 rpm for 30 minutes. Then, 12 g of deionized water and 120 g of toluene were added, and magnetic stirring was carried out at a speed of 1000 rpm for 10 minutes at 90°C. Finally, 34.19 g of maleimide was added, and magnetic stirring was carried out at 90°C for 10 minutes to obtain an epoxy resin composite system.

[0038] Preparation of breathable coating: 200 g of polytetrafluoroethylene, 130 g of epoxy resin composite system, 140 g of polypropylene, 11 g of leveling agent, 45 g of curing agent, and 13 g of defoaming agent were mixed, and stirred at a speed of 150 rpm for 20 minutes to obtain a breathable coating.

[0039] Preparation of highly breathable double-warp drying fabric: The drying net body is completely immersed in the breathable coating, left to stand for 40 minutes, then taken out and dried in an oven at 40°C for 4 hours to form a breathable coating on the surface of the drying net body, thereby obtaining a highly breathable double-warp drying net.

[0040] Example 4 Example 4 is based on Example 3. In Example 4, when preparing hydrophobic silica, 7.79 g of copper chloride dihydrate, 18.7 g of hexadecyltrimethylammonium bromide, and 33.51 g of ethyl orthosilicate are used.

[0041] Example 5 Example 5 is based on Example 3. In Example 5, when preparing hydrophobic silica, 7.23 g of copper chloride dihydrate, 21.69 g of hexadecyltrimethylammonium bromide, and 31.08 g of ethyl orthosilicate are used.

[0042] Example 6 Example 6 is based on Example 3, and the surfactant in Example 6 is polydimethylsiloxane (CAS No.: 9016-00-6).

[0043] Example 7 The examples are based on Example 3. In Example 7, the surfactant is sodium laureth sulfate (CAS No.: 1335-72-4).

[0044] Example 8 Example 8 is based on Example 3. In Example 9, when preparing the epoxy resin composite system, 150 g of epoxy resin, 14.29 g of furfurylamine, and 35.71 g of maleimide are used.

[0045] Example 9 Example 9 is based on Example 3. In Example 9, when preparing the epoxy resin composite system, 142.37 g of epoxy resin, 23.73 g of furfurylamine, and 33.9 g of maleimide are used.

[0046] Example 10 Example 10 is based on Example 3. In Example 10, when preparing the epoxy resin composite system, the amount of hydrophobic silica added is 5% of the mass of the epoxy resin.

[0047] Example 11 Example 11 is based on Example 3. In Example 11, when preparing the epoxy resin composite system, the amount of hydrophobic silica added is 9% of the mass of the epoxy resin.

[0048] Example 12 Example 12 is based on Example 3. In Example 12, when preparing the epoxy resin composite system, the hydrophobic silica is replaced with an equal amount of unmodified ordinary silica.

[0049] Comparative Example 1 Comparative Example 1 is based on Example 3. In Comparative Example 1, when preparing the epoxy resin composite system, the epoxy resin composite system is replaced with ordinary epoxy resin.

[0050] Performance testing The samples of Examples 1-12 and Comparative Example 1 were sampled and subjected to the following performance tests: (1) Breathability The air permeability of the prepared double-warp drying web was tested using the standard test method of GB / T5354-1997. Each sample was tested three times, and the average value was taken. The test results were entered in Table 1.

[0051] (2) Hydrophobicity The contact angle of each sample was measured three times, and the average value was taken. The test results were filled in Table 1.

[0052] (3) Tensile strength The tensile properties of the specimens were tested with reference to GB / T 3923.1-2013. The sample size was 25 cm × 5 cm, the tensile speed was 10 cm / min, and each specimen was tested three times. The average value was taken and the test results were filled in Table 1.

[0053] (4) Corrosion resistance The corrosion rate of the fabric was calculated by soaking a 20 cm x 20 cm drying net in an alkaline environment of pH 3.5 and pH 9.5 for 48 hours. Each sample was tested three times, and the average value was taken. The test results were entered in Table 1, where corrosion rate = corrosion area / total area × 100%.

[0054] Table 1 Performance test results of Examples 1-12 and Comparative Example 1 As shown in Table 1, the air permeability of Examples 1-3 is 87 mm / s or more, indicating that the drying net prepared in the present application has good air permeability; the hydrophobic angle of Examples 1-3 is 131° or more, indicating that the drying net prepared in the present application has good hydrophobicity; the tensile strength of Examples 1-3 is 52 MPa or more, indicating that the drying net prepared in the present application has good tensile properties; the corrosion rate of Examples 1-3 is 0.17% or less at pH = 3, and the corrosion rate is 0.24% or less at pH = 9.5, indicating that the drying net prepared in the present application has good corrosion resistance.

[0055] In Example 4 and Example 5, when preparing hydrophobic and hydrophobic silica, the mass ratio between copper chloride dihydrate, hexadecyltrimethylammonium bromide and ethyl orthosilicate is not within the range defined in the present application. When the amount of hexadecyltrimethylammonium bromide is too small, the dispersibility of the prepared silica is difficult to further improve, and the prepared hydrophobic and hydrophobic silica agglomerates in the system, affecting the overall stability of the system. When the content of hexadecyltrimethylammonium bromide is too much, the particle size of the nano-copper particles generated on the silica surface is difficult to further control, the particle size uniformity of the system is difficult to further improve, the stability decreases, and the overall performance of the system is affected. Therefore, the performance of Example 4 and Example 5 is reduced.

[0056] In Example 6, the surfactant was replaced with polydimethylsiloxane, and in Example 7, the surfactant was replaced with sodium lauryl polyether sulfate. Other surfactants were difficult to further interact with Cu, and the dispersibility and particle size were difficult to further improve. The catalytic activity of the system was difficult to further enhance, which affected the overall stability of the system. Therefore, the performance of Examples 6 and 7 were both reduced.

[0057] In Examples 8 and 9, when preparing the epoxy resin composite system, the mass ratios of the epoxy resin, furfurylamine and maleimide are not within the range specified in the present application. When the content of furfurylamine is too much or too little, it is difficult to further reversibly react with the maleimide group of maleimide, making it difficult to further improve the stability of the system, affecting the overall corrosion resistance of the system, and its cross-linking performance is difficult to further improve, affecting the overall stability of the system. Therefore, the performance of Examples 8 and 9 is reduced.

[0058] In Example 10 and Example 11, when preparing the epoxy resin composite system, the amount of hydrophobic silica added is not within the range specified in the present application. When the amount of hydrophobic silica added is small, the cross-linking performance between the epoxy resin and the epoxy resin is difficult to further improve, and the stability of the system decreases; when the content of hydrophobic silica is too much, silica agglomerates in the system, which reduces the overall stability of the system. Therefore, the performance of Example 10 and Example 11 is reduced.

[0059] In Example 12, when preparing the epoxy resin composite system, the hydrophobic silica was replaced with an equal amount of unmodified ordinary silica. The unmodified silica was dispersed in the system, and the hydrophobic performance was difficult to further improve. The dispersibility decreased, affecting the overall stability of the system. Therefore, the performance of Example 12 was reduced.

[0060] In Comparative Example 1, the epoxy resin composite system is replaced with ordinary epoxy resin. The hydrophobicity, corrosion resistance and strength of ordinary epoxy resin are difficult to further improve, so the performance of Comparative Example 1 is reduced.

[0061] This specific embodiment is merely an explanation of the present application and does not limit the present application. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present application. The technical scope of the present application is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A highly breathable double-warp drying net, characterized by: The invention comprises a drying net body and a breathable coating, wherein the breathable coating is formed by coating the breathable coating on the surface of the drying net body, and the breathable coating comprises the following components in mass fractions: 180-220 parts of polytetrafluoroethylene, 120-140 parts of epoxy resin composite system, 120-160 parts of polypropylene, 10-12 parts of leveling agent, 40-50 parts of curing agent, and 12-14 parts of defoaming agent; The raw materials of the epoxy resin composite system include hydrophobic silica, a silane coupling agent and epoxy resin.

2. The highly breathable double-warp drying net according to claim 1, characterized in that: The epoxy resin composite system is prepared by the following method: After mixing hydrophobic silica, toluene and silane coupling agent, ultrasonically obtain a mixed system, add epoxy resin and sustained-release agent to the mixed system, heat and stir, add water and toluene, magnetically stir, then add maleimide, and magnetically stir to obtain an epoxy resin composite system.

3. The highly breathable double-warp drying net according to claim 2, characterized in that: The sustained-release agent includes furfurylamine.

4. The highly breathable double-warp drying net according to claim 3, characterized in that: The mass ratio of the epoxy resin, furfurylamine and maleimide is 4.2:(0.5-0.6):

1.

5. The highly breathable double-warp drying net according to claim 2, characterized in that: The mass fraction of the hydrophobic silica is 6-8% of the mass of the epoxy resin.

6. The highly breathable double-warp drying net according to claim 1, characterized in that: The hydrophobic silica raw materials include surfactant, copper chloride dihydrate, ethyl orthosilicate and sodium borohydride.

7. The highly breathable double-warp drying net according to claim 6, characterized in that: The hydrophobic silica is prepared by the following method: Copper chloride dihydrate, ethanol and ammonia water are mixed and ultrasonicated, and then stirred in an ice water bath to obtain a mixture. A surfactant is mixed with ethanol, and then mixed with the mixture prepared above. Then, ethyl orthosilicate is added. After stirring, sodium borohydride is added to react, and the mixture is washed and freeze-dried to obtain hydrophobic silica.

8. The highly breathable double-warp drying net according to claim 7, characterized in that: The surfactant includes cetyltrimethylammonium bromide.

9. The highly breathable double-warp drying net according to claim 8, characterized in that: The mass ratio of the copper chloride dihydrate, hexadecyltrimethylammonium bromide and ethyl orthosilicate is 1:(2.6-2.8):4.

3.

10. The highly breathable double-warp drying fabric according to claim 1, characterized in that: The breathable coating is prepared by the following method: Polytetrafluoroethylene, epoxy resin composite system, polypropylene, leveling agent, curing agent and defoaming agent are mixed and stirred to obtain a breathable coating.

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