Water collector and preparation method thereof, cooling tower

Abstract

The present invention relates to the technical field of water collectors, and specifically to a water collector, a preparation method thereof, and a cooling tower. The water collector is assembled from water collector sheets, and the porosity per unit area of ​​the water collector sheets is 10-90%. The water collector sheets contain a hydrophilic surface, and the hydrophilic surface is a polypropylene sheet with a micro-nano structure, and the micro-nano structure is grafted with hydrophilic side groups, and the micro-nano structure exists in the form of protrusions and / or grooves. The surface grafting rate of the hydrophilic side groups in the hydrophilic surface is 10-50wt%. The present invention limits the water collector sheet to contain a hydrophilic surface, so that the water collector sheet has a water-collecting property and does not absorb water, thereby effectively improving the water recovery rate of the water collector sheet and maintaining stable performance. At the same time, the water collector has a simple structure and does not require frequent replacement of parts.

Description

Technical Field

[0001] The present invention relates to the technical field of water collectors, and in particular to a water collector and a preparation method thereof, and a cooling tower. Background Art

[0002] Cooling towers are widely used in the electric power, chemical, petroleum, metallurgy and other industries. They are one of the main equipment in industrial circulating water systems. Their function is to cool the hot water from process equipment in the circulating water system and then recycle it, which is related to energy conservation, emission reduction and environmental impact.

[0003] In the most common open cooling towers, water losses are inevitable. These losses include evaporation and windage, which together account for over half of the system's water consumption. The hot, humid air exhausted from the cooling tower carries some moisture. Some of this moisture is water vapor mixed with the air and cannot be mechanically separated. The other portion is small, mist-like droplets carried along with the airflow. These droplets are typically separated and recovered using a desiccant filter, minimizing water loss and improving the environment surrounding the tower. Typically, desiccant filters should feature high water removal efficiency, low ventilation resistance, cost-effectiveness, durability, and ease of installation.

[0004] Currently, drift collectors primarily use PVC or fiberglass sheets, but these materials are generally hydrophobic, resulting in low efficiency in collecting mist droplets. This leads to significant secondary entrainment of droplets and poor removal of tiny droplets, making it difficult to meet emission standards and energy conservation and emission reduction requirements. Improving the water collection efficiency of drift collectors and further enhancing water resource utilization is a critical issue for industrial cooling towers.

[0005] Therefore, a new water collector is urgently needed. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems of existing water collectors, such as the water collector being made of hydrophobic material, low water collection efficiency, large water loss, and difficulty in meeting emission standards and energy conservation and emission reduction requirements, and to provide a new water collector and its preparation method, a cooling tower, the water collector sheet having hydrophilicity or even super hydrophilicity, which can significantly improve the water recovery rate of the water collector; at the same time, the water collector has a simple structure and does not require frequent replacement of parts.

[0007] In order to achieve the above object, the first aspect of the present invention provides a water collector, which is assembled from water collector sheets, and the void ratio per unit area of ​​the water collector sheets is 10-90%;

[0008] The water collector sheet material contains a hydrophilic surface, and the hydrophilic surface is a polypropylene sheet material having a micro-nano structure, and the micro-nano structure is grafted with hydrophilic side groups, and the micro-nano structure exists in the form of protrusions and / or grooves;

[0009] Wherein, in the hydrophilic surface, the surface grafting rate of the hydrophilic side groups is 10-50 wt%.

[0010] Preferably, the water collector is assembled by water collector sheets at intervals of 3-50 mm through a skeleton.

[0011] A second aspect of the present invention provides a method for preparing a water eliminator, the method comprising the following steps:

[0012] (1) contacting a polypropylene sheet with an etchant and performing a first drying process to form protrusions and / or grooves having a micro-nano structure on the polypropylene sheet to obtain a modified polypropylene sheet;

[0013] (2) coating the modified polypropylene sheet with a monomer having a hydrophilic side group, and then irradiating the modified polypropylene sheet with microwaves to graft the hydrophilic side group onto the micro-nanostructure of the modified polypropylene sheet to obtain a hydrophilic surface;

[0014] (3) assembling the water collector sheets containing the hydrophilic surface to obtain a water collector;

[0015] Wherein, in the hydrophilic surface, the surface grafting rate of the hydrophilic side groups is 10-50 wt%.

[0016] A third aspect of the present invention provides a cooling tower, wherein the water collector provided by the first aspect, or the water collector produced by the method provided by the second aspect, is provided inside the cooling tower.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The water collector provided by the present invention is defined as being assembled from water collector sheets having a hydrophilic surface, and further defined as a polypropylene sheet having a micro-nano structure, wherein the hydrophilic surface is grafted with hydrophilic side groups, so that the hydrophilic surface is effectively improved in hydrophilicity and has stable performance while ensuring that the mechanical properties are not affected, so that the water collector sheet has a water-collecting property and does not absorb water, thereby effectively improving the water recovery rate of the water collector sheet and having stable performance; at the same time, the structure of the water collector is simple, and there is no need to frequently replace parts;

[0019] (2) The method provided by the present invention combines physical modification (etching) and chemical modification (grafting), which can effectively improve the hydrophilicity or even super-hydrophilicity of the hydrophilic surface. In combination with the assembly method of the water collector sheet containing the hydrophilic surface, the water collector has a high water recovery rate. At the same time, the method is simple in process, easy to operate, and convenient for industrial large-scale production.

[0020] (3) The water collector provided by the present invention is used in a cooling tower, which can effectively improve the water collection rate of the cooling tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of a water collector provided by the present invention;

[0022] Figure 2 This is a schematic structural diagram of another water collector provided by the present invention. DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0024] In the present invention, unless otherwise specified, the terms "first", "second" and "third" do not indicate a sequence of precedence or a limitation on the materials or steps. They are only used to distinguish the same material or step. For example, the terms "first", "second" and "third" in "first drying", "second drying", "third drying" and "fourth drying" are only used to distinguish that these are not the same drying.

[0025] A first aspect of the present invention provides a water collector, which is assembled from water collector sheets, and the void ratio per unit area of ​​the water collector sheets is 10-90%;

[0026] The water collector sheet material contains a hydrophilic surface, and the hydrophilic surface is a polypropylene sheet material having a micro-nano structure, and the micro-nano structure is grafted with hydrophilic side groups, and the micro-nano structure exists in the form of protrusions and / or grooves;

[0027] Wherein, in the hydrophilic surface, the surface grafting rate of the hydrophilic side groups is 10-50 wt%.

[0028] The water collector sheet material provided by the present invention, which has a hydrophilic surface, has hydrophilic properties and can collect small water droplets in steam when steam flows. The small water droplets gather into large droplets on the folded or serpentine surface of the water collector sheet material and fall back to the bottom of the cooling tower along the slope. The surface of the water collector sheet material only has the property of collecting water and does not absorb water, and does not suffer from the disadvantage of a significant decrease in water collection performance after absorbing water. Therefore, the water collector assembled with the water collector sheet material has high water recovery efficiency and a simple structure, without the need for frequent replacement of parts. At the same time, the hydrophilic surface is a polypropylene sheet material with a micro-nano structure on the surface. The micro-nano structure is grafted with hydrophilic side groups, and the micro-nano structure exists in the form of protrusions and / or grooves. The hydrophilic side groups are used to collect droplets in the airflow when steam flows through, further improving the hydrophilicity of the hydrophilic surface and the water recovery rate.

[0029] In the present invention, unless otherwise specified, the void ratio per unit area of ​​the water collector sheet refers to the ratio of the voids to the area occupied by the water retaining device when viewed from above, excluding the area occupied by the sheet and the thickness of the optional substrate. The void ratio per unit area parameter is measured by an area calculation method.

[0030] In some embodiments of the present invention, the void ratio per unit area of ​​the desiccant sheet is preferably 10-90%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or any value within a range consisting of any two values, preferably 30-90%. Using this preferred condition is more conducive to improving the water recovery rate of the desiccant sheet.

[0031] In some embodiments of the present invention, preferably, the shape of the water collector sheet after assembly is folded or serpentine.

[0032] In some embodiments of the present invention, preferably, the water collector is assembled from water collector sheets at intervals of 3-50 mm through a skeleton.

[0033] In the present invention, unless otherwise specified, the frame has a supporting function. Preferably, the frame includes but is not limited to a fiberglass frame.

[0034] In some embodiments of the present invention, preferably, the water collector sheet comprises: an optional substrate and a hydrophilic surface supported on the substrate. In the present invention, unless otherwise specified, the substrate includes but is not limited to a PVC substrate.

[0035] The present invention provides a structural diagram of a water collector, such as Figure 1 As shown, the water collector is assembled from water collector sheets at intervals of 3-50 mm through a glass fiber reinforced plastic frame, wherein the water collector sheets have a hydrophilic surface.

[0036] The structural diagram of another water collector provided by the present invention is as follows: Figure 2 As shown, the water collector is assembled from water collector sheets at intervals of 3-50 mm through a glass fiber reinforced plastic frame, wherein the water collector sheets are a PVC substrate and a hydrophilic surface supported on the PVC substrate.

[0037] In some embodiments of the present invention, preferably, the polypropylene sheet is a foamed polypropylene sheet.

[0038] In some embodiments of the present invention, preferably, the surface average pore size of the foamed polypropylene sheet is 10-100 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, and any value in a range consisting of any two numerical values, preferably 20-60 μm; the flexural strength is 0.1-1 MPa, for example, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.7 MPa, 0.9 MPa, 1 MPa, and any value in a range consisting of any two numerical values, preferably 0.1-0.5 MPa; the thickness is 0.1-1 cm, for example, 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.8 cm, 1 cm, and any value in a range consisting of any two numerical values, preferably 0.1-0.5 cm. Adopting the preferred conditions is more conducive to forming protrusions and / or grooves with larger length and depth on the polypropylene sheet.

[0039] In the present invention, unless otherwise specified, the surface average pore size parameter is measured by the statistical average method of three surface scans using a scanning electron microscope; the bending strength parameter is measured by the GB / T 9341-2008 polypropylene three-point bending test method; and the thickness parameter is measured by the vernier caliper test method.

[0040] In some embodiments of the present invention, the foamed polypropylene sheet is preferably foamed from at least one selected from a homopolymer polypropylene sheet having a polypropylene content of ≥50 wt%, a random copolymer polypropylene sheet, and an impact copolymer polypropylene sheet. In the present invention, the foaming process has a wide range of options, and the sheet can be produced by chemical foaming or physical foaming.

[0041] In the present invention, the source of the foamed polypropylene sheet has a wide range of choices, as long as the polypropylene sheet is made by foaming. In the present invention, the foamed polypropylene sheet can be obtained by purchase or by preparation, and the present invention will not go into details here.

[0042] In a preferred embodiment of the present invention, the foamed polypropylene sheet is prepared by foaming a polypropylene sheet using supercritical carbon dioxide.

[0043] In some embodiments of the present invention, preferably, the content of polypropylene in the foamed polypropylene sheet is ≥50 wt%, preferably 50-90 wt%.

[0044] In some embodiments of the present invention, preferably, the weight average molecular weight of the polypropylene is 10 4 -10 6g / mol; the melt index at 230°C and a load of 2.16 kg is 0.1-15 g / 10 min, for example, 0.1 g / 10 min, 1 g / 10 min, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 10 g / 10 min, 15 g / 10 min, and any value in a range consisting of any two values, preferably 1-7 g / 10 min.

[0045] In the present invention, unless otherwise specified, the melt index parameters are measured by the GB / T3682.1-2018 method.

[0046] In the present invention, unless otherwise specified, the micro-nano structure refers to protrusions and / or grooves having micrometer or nanometer scale characteristic dimensions and arranged in a specific manner.

[0047] In some embodiments of the present invention, preferably, the length of the micro-nanostructure is 1 nm-100 μm, for example, 1 nm, 10 nm, 100 nm, 200 nm, 500 nm, 1 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 100 μm, and any value in a range consisting of any two values, preferably 500 nm-50 μm; the depth is 1 μm-1 mm, for example, 1 μm, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 400 μm, 500 μm, 700 μm, 900 μm, 1 mm, and any value in a range consisting of any two values, preferably 50-500 μm. In the present invention, the micro-nano structure is conducive to improving the surface wettability. For example, when the flat surface is hydrophilic (<90°), the surface with the micro-nano structure has a capillary effect on water, which can further wet the water and thus show a more hydrophilic or even super-hydrophilic state.

[0048] In some embodiments of the present invention, the surface grafting rate of the hydrophilic side groups is 10-50wt%, for example, 10wt%, 20wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, and any value in a range consisting of any two of these values, preferably 30-40wt%. Adopting the preferred conditions is more conducive to improving the hydrophilicity of the hydrophilic surface.

[0049] In the present invention, unless otherwise specified, the surface grafting rate parameter is measured by using the energy spectrum accessory of the S4800 scanning electron microscope of Hitachi, Japan, to measure the content of the main elements of the grafted components on the hydrophilic surface, and the content of the grafted material on the hydrophilic surface is inferred from the molecular formula of the grafted material as the surface grafting rate.

[0050] In the present invention, the hydrophilic side group has a wide range of selection, as long as the hydrophilic side group contains a hydrophilic group. Preferably, the hydrophilic side group is a side group containing a heteroatom of at least one element selected from oxygen, sulfur, nitrogen, silicon and halogen and a carbon-carbon double bond.

[0051] In the present invention, unless otherwise specified, the halogen is selected from at least one of fluorine, chlorine, bromine and iodine, preferably fluorine and / or chlorine.

[0052] In some embodiments of the present invention, preferably, the monomer of the hydrophilic side group is selected from at least one of an organic acid, an organic acid derivative, and a vinyl silane, wherein the organic acid includes but is not limited to carboxylic acid, sulfonic acid, sulfinic acid, thiocarboxylic acid, and the like.

[0053] In some embodiments of the present invention, preferably, the organic acid derivative is selected from at least one of anhydrides, esters and salts of organic acids.

[0054] In some specific embodiments of the present invention, preferably, the monomer of the hydrophilic side group is selected from at least one of maleic anhydride and / or its derivatives, acrylic acid and / or its derivatives, methacrylic acid and / or its derivatives, vinyl acetate, olefin sulfonic acid and / or its derivatives, p-phenylene formic acid and / or its derivatives, p-phenylene acetic acid and / or its derivatives, itaconic acid, oleic acid and arachidonic acid.

[0055] In some embodiments of the present invention, preferably, the general formula of the vinyl silane is: CH2=CH2(CH2) n SiX3, wherein n=0-3, and X is selected from at least one of chloro, methoxy, ethoxy, methoxy, ethoxy and acetoxy groups.

[0056] In some specific embodiments of the present invention, preferably, the vinyl silane is selected from vinyl trimethoxy silane and / or vinyl triethoxy silane.

[0057] According to the present invention, preferably, the water contact angle of the water collector sheet is less than 30°, preferably 0-20°, more preferably 0°; the water recovery rate is greater than 50wt%, preferably 60-100wt%; and the humidity is less than 90%, preferably less than 80%.

[0058] In the present invention, unless otherwise specified, the water contact angle parameters are measured using the EASY DROP contact angle tester from KRUSS, Germany, with a measurement range of 1-180° and a resolution of ±0.1°. The dynamic contact angle measurement mode is adopted, and a fixed volume of 2 μL of deionized water droplets or white oil droplets is dropped on the hydrophilic surface each time. The calculated initial contact angle is taken as the contact angle measurement value of the hydrophilic surface. The measurements are performed in parallel 6 times, and the average value is calculated.

[0059] In the present invention, unless otherwise specified, the water recovery rate parameter test is as follows: the water collector is installed in a cooling tower with a flow rate of 5t / h, 100kg of water is pre-placed at the bottom of the cooling tower, and the room temperature is set to 16°C; a pipe heater is used to make the water temperature at the cooling tower inlet constant at 40°C, and a water collector is made with PVC sheet as the water collector sheet with a porosity of 30%, 50%, 70%, and 90%. After installation, the equipment is circulated for 24 hours, and the water volume at the bottom of the cooling tower after 24 hours is tested. The test is performed three times, and the average water loss of the cooling tower is calculated three times, which are recorded as A1=5.3kg, A2=6.1kg, A3=7.1kg, and A4=9.6kg respectively; then different hydrophilic surfaces prepared by this method are used as water collector sheets to make water collectors, and the water loss B after 24 hours is calculated according to different installation methods and different porosities, and then the water recovery rate a compared with the PVC sheet is calculated; the calculation formula is as follows: a=(AB) / A×100%.

[0060] In the present invention, unless otherwise specified, the humidity parameter test is as follows: after installing the water collector in the cooling tower, circulate the equipment for 24 hours and then use a hygrometer to test the air humidity at a position 50 cm above the middle of the water collector sheet of the cooling tower.

[0061] According to a particularly preferred embodiment of the present invention, the water collector is assembled from water collector sheets at intervals of 3-50 mm through a skeleton, and the void ratio per unit area of ​​the water collector sheets is 10-90%;

[0062] The water collector sheet comprises an optional substrate and a hydrophilic surface supported on the substrate, wherein the hydrophilic surface is a foamed polypropylene sheet having a micro-nano structure, the micro-nano structure is grafted with hydrophilic side groups, and the micro-nano structure exists in the form of protrusions and / or grooves;

[0063] Wherein, in the hydrophilic surface, the surface grafting rate of the hydrophilic side groups is 10-50wt%;

[0064] The average pore size of the foamed polypropylene sheet is 10-100 μm; the bending strength is 0.1-1 MPa; and the thickness is 0.1-1 cm.

[0065] The hydrophilic surface is prepared by the following method: contacting a foamed polypropylene sheet with an etchant and performing a first drying to form protrusions and / or grooves with a micro-nano structure on the foamed polypropylene sheet to obtain a modified foamed polypropylene sheet; coating the modified foamed polypropylene sheet with a hydrophilic side group monomer, and then performing microwave irradiation to graft hydrophilic side groups on the micro-nano structure of the foamed polypropylene sheet.

[0066] A second aspect of the present invention provides a method for preparing a water eliminator, the method comprising the following steps:

[0067] (1) contacting a polypropylene sheet with an etchant and performing a first drying process to form protrusions and / or grooves having a micro-nano structure on the polypropylene sheet to obtain a modified polypropylene sheet;

[0068] (2) coating the modified polypropylene sheet with a monomer having a hydrophilic side group, and then irradiating the modified polypropylene sheet with microwaves to graft the hydrophilic side group onto the micro-nanostructure of the modified polypropylene sheet to obtain a hydrophilic surface;

[0069] (3) assembling the water collector sheets containing the hydrophilic surface to obtain a water collector;

[0070] Wherein, in the hydrophilic surface, the surface grafting rate of the hydrophilic side groups is 10-50 wt%.

[0071] In the method provided by the present invention, hydrophilic side groups can be grafted onto a modified polypropylene sheet without the addition of an initiator. In other words, the hydrophilic surface produced by the method provided by the present invention does not contain initiator residues, thereby improving the hydrophilicity of the hydrophilic surface while ensuring that the mechanical properties of the hydrophilic surface are not affected.

[0072] In the present invention, in step (1), the polypropylene sheet is in accordance with the above-mentioned definition, which will not be elaborated in detail in the present invention.

[0073] In some embodiments of the present invention, preferably, in step (1), the weight ratio of the propylene sheet to the etchant is 0.1-100:100, for example, 0.1:100, 0.5:100, 1:100, 5:100, 10:100, 20:100, 30:100, 40:100, 50:100, 60:100, 80:100, 100:100, and any value in a range consisting of any two values, preferably 0.5-50:100, more preferably 1-30:100. The preferred weight ratio allows the etchant to evenly cover the surface of the polypropylene sheet, which is more conducive to sufficient contact and mixing between the two, thereby facilitating the formation of micro-nano structures on the surface of the polypropylene sheet.

[0074] In the present invention, the etchant has a wide range of options, as long as it can etch the surface of the polypropylene sheet. Preferably, the etchant is a polar organic solvent selected from at least one of toluene, xylene, diphenyl ether, butyl acetate, isoamyl acetate, n-heptane, n-octane, and decalin.

[0075] In the present invention, the contact conditions have a wide range of selection. Preferably, in step (1), the contact conditions include: a temperature of 15-70°C, preferably 20-60°C; and a time of 1-24 hours, preferably 5-15 hours.

[0076] In the present invention, the contacting method has a wide range of options. Preferably, the contacting method is immersion, that is, the polypropylene sheet is immersed in the etchant, wherein the immersion temperature is 15-70° C. and the immersion time is 1-24 hours.

[0077] In the present invention, the first drying is intended to remove the etchant in the contact product. Preferably, the first drying conditions include: a temperature of 80-120°C, preferably 80-100°C; and a time of 1-10 hours, preferably 1-5 hours.

[0078] In some embodiments of the present invention, preferably, in step (2), the weight ratio of the hydrophilic side group monomer to the modified polypropylene sheet is 10-50:100, for example, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100, 50:100, and any value in a range consisting of any two values, preferably 10-30:100. The preferred weight ratio is conducive to sufficient mixing of the raw materials and grafting reaction, thereby increasing the grafting rate of the hydrophilic side groups on the hydrophilic surface.

[0079] In the present invention, in step (2), the monomer of the hydrophilic side group is in accordance with the above-mentioned definition, which will not be elaborated in detail in the present invention.

[0080] In the present invention, the coating method has a wide range of options, as long as the monomer with hydrophilic side groups is evenly coated on the modified polypropylene sheet. Preferably, the coating method is mechanical direct spreading or liquid spraying above the melting point of the monomer.

[0081] In one embodiment of the present invention, the hydrophilic side group monomer is mechanically sprayed onto the modified polypropylene sheet. During microwave irradiation, the hydrophilic side group monomer undergoes a process of first liquefying and then vaporizing. The vaporization process allows the hydrophilic side groups to be evenly grafted onto the modified polypropylene sheet.

[0082] In the present invention, the microwave irradiation conditions have a wide range of options, as long as the hydrophilic side group monomer is grafted onto the modified polypropylene sheet. Preferably, the microwave irradiation conditions include: an irradiation power of 1500-27000W, preferably 1500-15000W; and an irradiation time of 1 second to 1 minute, preferably 1-30 seconds.

[0083] In some embodiments of the present invention, preferably, the number of microwave irradiation is ≥ 1 times, preferably 1-5 times.

[0084] According to the present invention, the microwave irradiation process can preferably be repeated multiple times, preferably 1-5 times, using the same irradiation power and the same irradiation time. Repeated cycles allow the foamed polypropylene sheet to repeat the process of grafting monomer vaporization and grafting, which is beneficial for uniformity of excess grafted monomer and improvement of the grafting rate.

[0085] In the present invention, unless otherwise specified, the microwave irradiation is carried out in various microwave reactors available in the prior art.

[0086] In some embodiments of the present invention, preferably, in step (3), the assembling method includes: assembling the water collector sheets through a skeleton at intervals of 3-50 mm.

[0087] In the present invention, unless otherwise specified, the type of the skeleton and the water collector sheet are in accordance with the above-mentioned definitions, and the present invention will not elaborate on them here.

[0088] According to the present invention, preferably, the method further comprises: before the assembling, washing and second drying the microwave irradiated product to remove unreacted hydrophilic side group monomers in the microwave irradiated product.

[0089] In the present invention, there is a wide range of options for the cleaning method, as long as the residual monomers with hydrophilic side groups can be removed.

[0090] In some embodiments of the present invention, preferably, the microwave irradiated product is immediately soaked in a cleaning solution with a volume exceeding that of the microwave irradiated product at high temperature for 5-15 minutes, and then excess water is removed using a filtration device; the washing is repeated 2-6 times to obtain a clean microwave irradiated product.

[0091] In the present invention, the cleaning liquid has a wide range of choices. Preferably, the cleaning liquid is selected from water and / or an organic solvent, preferably at least one selected from alcohol, ketone, ester and water, more preferably alcohol and / or water.

[0092] According to the present invention, preferably, the method further comprises: when the monomer of the hydrophilic side group is an organic acid, an anhydride and / or ester of an organic acid, subjecting the second dried product to a salification reaction with a base, and washing and third drying the product of the salification reaction, in order to convert the grafted hydrophilic side group into an organic acid salt, thereby further improving the hydrophilicity of the hydrophilic surface.

[0093] In the present invention, the base has a wide range of choices, as long as the organic acid, anhydride and / or ester of the organic acid is converted into a salt through a salification reaction. Preferably, the base is selected from hydroxide and / or ammonia water, preferably hydroxide.

[0094] In some embodiments of the present invention, preferably, the hydroxide is selected from at least one of sodium hydroxide, potassium hydroxide, barium hydroxide, lithium hydroxide, strontium hydroxide, calcium hydroxide, ferric hydroxide, ferrous hydroxide, zinc hydroxide, magnesium hydroxide, cobalt hydroxide, gold hydroxide, aluminum hydroxide, copper hydroxide, beryllium hydroxide and rare earth hydroxides, preferably selected from at least one of sodium hydroxide, potassium hydroxide, barium hydroxide, lithium hydroxide, strontium hydroxide and calcium hydroxide.

[0095] In some embodiments of the present invention, preferably, the weight ratio of the alkali to the modified polypropylene sheet is 10-25:100, for example, 10:100, 12:100, 15:100, 16:100, 18:100, 20:100, 22:100, 24:100, 25:100, and any value in the range consisting of any two values, preferably 10-20:100.

[0096] In the present invention, the base can be directly reacted with the third dried product to undergo a salification reaction. Alternatively, for better salification effect, the base is preferably present in the form of alkali solution, that is, an alkali-containing aqueous solution is used to perform the salification reaction.

[0097] In some embodiments of the present invention, preferably, in the alkali solution, the weight ratio of alkali to water is 0.1-100:100, for example, 0.1:100, 0.5:100, 1:100, 2:100, 3:100, 5:100, 10:100, 20:100, 30:100, 40:100, 50:100, 80:100, 100:100, and any value in a range consisting of any two values, preferably 0.5-50:100, preferably 1-30:100. Using the preferred weight ratio is more conducive to improving the efficiency of the salification reaction and enhancing the hydrophilicity of the hydrophilic surface.

[0098] In the present invention, the conditions for the salification reaction have a wide range of selection. Preferably, the salification reaction time is 1-30 minutes, preferably 5-10 minutes. In the present invention, the temperature and pressure of the salification reaction are not limited, and are generally room temperature and pressure.

[0099] In some embodiments of the present invention, preferably, the product of the salification reaction is immediately soaked in a solvent with a volume exceeding that of the grafted polypropylene sheet for 5-15 minutes, and then excess water is removed using a filtration device; this is repeated 2-6 times to obtain a clean salification reaction product.

[0100] In the present invention, the second drying and the third drying can be carried out by forced air drying or room temperature drying, which will not be described in detail in the present invention. Preferably, the temperature of the second drying and the third drying does not exceed 140°C (the melting point of random copolymer polypropylene is 140+°C) to avoid melting of the polypropylene sheet.

[0101] A third aspect of the present invention provides a cooling tower, wherein the interior of the cooling tower is provided with the water collector provided by the first aspect, or the water collector produced by the method provided by the second aspect.

[0102] The water collector sheet material with a hydrophilic surface provided by the present invention is more hydrophilic than a polypropylene sheet material, and even achieves super-hydrophilic performance; at the same time, the water collector sheet material provided by the present invention does not reduce the molecular weight of the polypropylene sheet material, has no residual monomers with hydrophilic side groups, does not introduce initiators, is colorless and odorless, has greatly improved hydrophilicity and is long-lasting and stable, and has a more obvious water collection effect when set in a cooling tower.

[0103] The present invention will be described in detail below through examples.

[0104] The water contact angle parameters were measured using the EASY DROP contact angle tester from KRUSS, Germany, with a measurement range of 1-180° and a resolution of ±0.1°. The dynamic contact angle measurement mode was used, and a fixed volume of 2 μL of deionized water droplets or white oil droplets were dropped onto the hydrophilic surface. The calculated initial contact angle was taken as the contact angle measurement value of the hydrophilic surface. Six parallel measurements were performed, and the average value was calculated.

[0105] The surface grafting rate parameter was measured by the energy spectrum accessory of Hitachi S4800 scanning electron microscope to measure the content of the main elements of the grafted components on the hydrophilic surface, and the content of the grafted material on the hydrophilic surface was inferred from the molecular formula of the grafted material as the surface grafting rate.

[0106] Water recovery rate parameter test: The water collector is installed in a cooling tower with a flow rate of 5t / h, 100kg of water is pre-placed at the bottom of the cooling tower, and the room temperature is set to 16°C; a pipe heater is used to make the water temperature at the cooling tower inlet constant at 40°C, and a water collector is made with PVC sheet as the water collector sheet with a porosity of 30%, 50%, 70%, and 90%. After installation, the equipment is circulated for 24 hours, and the water volume at the bottom of the cooling tower after 24 hours is tested. The test is conducted three times, and the average water loss of the cooling tower is calculated three times, which are recorded as A1=5.3kg, A2=6.1kg, A3=7.1kg, and A4=9.6kg respectively; then different hydrophilic surfaces prepared by this method are used as water collector sheets to make water collectors. According to different installation methods and different porosities, the water loss B after 24 hours is calculated, and then the water recovery rate a compared with the PVC sheet is calculated; the calculation formula is as follows: a=(AB) / A×100%

[0107] Humidity parameter test: After installing the water collector in the cooling tower, circulate the equipment for 24 hours and then use a hygrometer to test the air humidity at a location 50 cm above the center of the water collector sheet of the cooling tower.

[0108] The foamed polypropylene sheet-1 is prepared by foaming the injection-molded polypropylene sheet-1 with supercritical carbon dioxide; wherein the foamed polypropylene sheet-1 contains 90 wt % of random copolymerized polypropylene, has an average surface pore size of 50 μm, and a bending strength of 0.15 MPa; and has a thickness of 0.1 cm.

[0109] The foamed polypropylene sheet-2 is prepared by foaming the injection-molded polypropylene sheet-2 with supercritical carbon dioxide; wherein the foamed polypropylene sheet-2 contains 70 wt % random copolymer polypropylene, an average surface pore size of 40 μm, a bending strength of 0.45 MPa, and a thickness of 0.5 cm.

[0110] The foamed polypropylene sheet-3 is prepared by foaming the injection-molded polypropylene sheet-3 with supercritical carbon dioxide; wherein the foamed polypropylene sheet-3 contains 80 wt % of random copolymerized polypropylene, an average surface pore size of 25 μm, a bending strength of 0.33 MPa, and a thickness of 1 cm.

[0111] Injection molded polypropylene sheet-1 (a blend of 70 wt% random copolymer polypropylene E02ES and 30 wt% POE) was purchased from Jiangsu Suzhou Shensai New Materials Co., Ltd., with a smooth surface, a bending strength of 10.5 MPa, and a thickness of 0.1 cm.

[0112] Injection molded polypropylene sheet-2 (a blend of 90 wt% random copolymer polypropylene E02ES and 10 wt% homopolymer polypropylene T30S) was purchased from Zhejiang Jiaxing Xinhengtai New Materials Co., Ltd. It has a smooth surface, a bending strength of 17.5 MPa, and a thickness of 0.1 cm.

[0113] Injection molded polypropylene sheet-3 (random copolymer polypropylene E02ES) was purchased from Ningbo Zhiwei New Material Technology Co., Ltd., with a smooth surface, a bending strength of 15.0 MPa, and a thickness of 0.1 cm.

[0114] Xylene (Sinopharm Chemical Reagent Co., Ltd.), decahydronaphthalene (Sinopharm Chemical Reagent Co., Ltd.), maleic anhydride (Xilong Scientific Co., Ltd.), acrylic acid (Sinopharm Chemical Reagent Co., Ltd.), methacrylic acid (Sinopharm Chemical Reagent Co., Ltd.), 2-acrylamido-2-methylpropanesulfonic acid (Sinopharm Chemical Reagent Co., Ltd.), sodium hydroxide (Xilong Scientific Co., Ltd.), potassium hydroxide (Xilong Scientific Co., Ltd.), calcium hydroxide (Xilong Scientific Co., Ltd.), acetone (Xilong Scientific Co., Ltd.), sodium chloride (Sinopharm Chemical Reagent Co., Ltd.), and vinyltrimethoxysilane (Tokyo Chemical Industry Co., Ltd.); other raw materials were commercially available.

[0115] The physical properties of the hydrophilic surfaces and water collector sheets prepared in the examples and comparative examples are listed in Table 1.

[0116] Example 1

[0117] (1) 10 g of a polypropylene sheet (foamed polypropylene sheet-1, water contact angle of 108°) was immersed in 100 g of an etchant (xylene), sealed and immersed in a thermostat at 25°C for 12 h, and then placed in a forced air drying oven at 90°C for 2 h to obtain a modified polypropylene sheet;

[0118] (2) dissolving 10 parts by weight of alkali (sodium hydroxide) in 50 parts by weight of deionized water to obtain an alkali solution;

[0119] 10 parts by weight of maleic anhydride powder was mechanically sprayed onto 100 parts by weight of a modified polypropylene sheet, and microwave irradiated at a power of 2000 W for 25 seconds, with two cycles of 1 minute between each cycle. The microwave-irradiated product was soaked in deionized water for 10 minutes, and the deionized water was replaced three times to ensure that the maleic anhydride that did not participate in the grafting reaction was removed. The washed product was then placed in a forced air dryer at 80°C.

[0120] The dried product was subjected to a salification reaction with the alkali solution for 5 minutes, and the salification reaction product was immersed in deionized water for 10 minutes, and the deionized water was changed 3 times to ensure that the unreacted alkali was removed. The washed product was then placed in a forced air drying at 80° C. to obtain a hydrophilic surface S1;

[0121] (3) The PVC substrate and the hydrophilic surface S1 loaded on the PVC substrate are used as the water collector sheet Q1, and the water collector is assembled from the water collector sheets Q1. The interval of the water collector sheets Q1 is adjusted to 7 mm so that the unit area porosity of the water collector sheets Q1 is 30%.

[0122] Example 2

[0123] (1) 10 g of a polypropylene sheet (foamed polypropylene sheet-1, water contact angle of 108°) was immersed in 100 g of an etchant (xylene), sealed and immersed in a thermostat at 25°C for 12 h, and then placed in a forced air drying oven at 90°C for 2 h to obtain a modified polypropylene sheet;

[0124] (2) dissolving 10 parts by weight of alkali (potassium hydroxide) in 50 parts by weight of deionized water to obtain an alkali solution;

[0125] 20 parts by weight of maleic anhydride powder was mechanically sprayed onto 100 parts by weight of a modified polypropylene sheet, and microwave irradiation was performed at an irradiation power of 5000 W for 20 seconds, with a 1-minute interval between each cycle. The microwave-irradiated product was soaked in deionized water for 10 minutes, and the deionized water was replaced three times to ensure that the maleic anhydride that did not participate in the grafting reaction was removed. The washed product was then placed in a forced air dryer at 80°C for drying.

[0126] The dried product was subjected to a salification reaction with the alkali solution for 5 minutes, and the salification reaction product was soaked in deionized water for 10 minutes, and the deionized water was changed 3 times to ensure that the unreacted alkali was removed. The washed product was then placed in a forced air drying at 80° C. to obtain a hydrophilic surface S2;

[0127] (3) The hydrophilic surface S2 is used as the water collector sheet Q2, and the water collector is assembled from the water collector sheets Q2. The interval of the water collector sheets Q2 is adjusted to 10 mm, so that the unit area porosity of the water collector sheets Q2 is 50%.

[0128] Example 3

[0129] (1) 10 g of a polypropylene sheet (foamed polypropylene sheet-2, water contact angle of 112°) was immersed in 90 g of an etchant (decalin), sealed and immersed in a thermostat at 50°C for 4 h, and then placed in a forced air drying oven at 80°C for 2 h to obtain a modified polypropylene sheet;

[0130] (2) dissolving 25 parts by weight of alkali (potassium hydroxide) in 100 parts by weight of deionized water to obtain an alkali solution;

[0131] 30 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid powder was mechanically sprayed onto 100 parts by weight of a modified polypropylene sheet, and microwave irradiation was performed at an irradiation power of 10,000 W for 10 seconds, with a 1-minute interval between each cycle. The microwave-irradiated product was soaked in deionized water for 10 minutes, and the deionized water was replaced three times to ensure that the 2-acrylamide-2-methylpropanesulfonic acid that did not participate in the grafting reaction was removed. The washed product was then placed in a forced air dryer at 80°C for drying.

[0132] The dried product was subjected to a salification reaction with the alkali solution for 5 minutes, and the salification reaction product was soaked in deionized water for 10 minutes, and the deionized water was changed 3 times to ensure that unreacted alkali was removed. The washed product was then placed in a forced air dryer at 80° C. to obtain a hydrophilic surface S3;

[0133] (3) The PVC substrate and the hydrophilic surface S3 loaded on the PVC substrate are used as the water collector sheet Q3, and the water collector is assembled from the water collector sheets Q3. The interval of the water collector sheets Q3 is adjusted to 12 mm so that the unit area porosity of the water collector sheet Q3 is 70%.

[0134] Example 4

[0135] (1) 10 g of a polypropylene sheet (foamed polypropylene sheet-3, water contact angle of 108°) was immersed in 90 g of an etchant (decalin), and the mixture was sealed and immersed in a thermostat at 25°C for 10 h, and then placed in a forced air drying oven at 80°C for 2 h to obtain a modified polypropylene sheet;

[0136] (2) dissolving 20 parts by weight of alkali (potassium hydroxide) in 50 parts by weight of deionized water to obtain an alkali solution;

[0137] 50 parts by weight of methacrylic acid liquid was mechanically sprayed onto 100 parts by weight of a modified polypropylene sheet, and microwave irradiation was performed at an irradiation power of 15,000 W for 3 seconds, with a cycle of 5 times, each time with an interval of 1 minute. The microwave-irradiated product was soaked in deionized water for 10 minutes, and the deionized water was replaced 3 times to ensure that the methacrylic acid that did not participate in the grafting reaction was removed. The washed product was then placed in a forced air drying at 80° C. to obtain a hydrophilic surface S4.

[0138] (3) The hydrophilic surface S4 is used as the water collector sheet Q4, and the water collector is assembled from the water collector sheets Q4. The interval between the water collector sheets Q4 is adjusted to 20 mm so that the porosity per unit area of ​​the water collector sheets Q4 is 90%.

[0139] Example 5

[0140] (1) 10 g of a polypropylene sheet (foamed polypropylene sheet-3, water contact angle of 108°) was immersed in 90 g of an etchant (decalin), and the mixture was sealed and immersed in a thermostat at 25°C for 10 h, and then placed in a forced air drying oven at 80°C for 2 h to obtain a modified polypropylene sheet;

[0141] (2) 40 parts by weight of vinyltrimethoxysilane liquid was coated on 100 parts by weight of modified polypropylene sheet by mechanical spraying, and microwave irradiated at an irradiation power of 20,000 W for 2 seconds, and the cycle was repeated 4 times, with an interval of 1 minute each time; and the microwave irradiated product was soaked in deionized water for 10 minutes, and the deionized water was replaced 3 times to ensure that the vinyltrimethoxysilane that did not participate in the grafting reaction was removed, and then the washed product was placed in a forced air drying at 80° C. to obtain a hydrophilic surface S5;

[0142] (3) The hydrophilic surface S5 is used as the water collector sheet Q5, and the water collector is assembled from the water collector sheets Q5. The interval of the water collector sheets Q5 is adjusted to 20 mm so that the porosity per unit area of ​​the water collector sheets Q5 is 90%.

[0143] Example 6

[0144] The method of Example 1 was followed, except that in step (1), 10 g of polypropylene sheet (foamed polypropylene sheet-1, with a water contact angle of 108°) was replaced with 35 g of polypropylene sheet (foamed polypropylene sheet-1, with a water contact angle of 108°), and the other conditions were the same, to obtain a hydrophilic surface S6 and a water collector sheet Q6.

[0145] Example 7

[0146] The method of Example 1 is followed, except that in step (2), 10 parts by weight of maleic anhydride powder is replaced by 50 parts by weight of maleic anhydride powder, and the other conditions are the same, to obtain a hydrophilic surface S7 and a water collector sheet Q7.

[0147] Example 8

[0148] The method of Example 1 is followed, except that in step (2), the microwave irradiation conditions are modified to: microwave irradiation at an irradiation power of 27000 W for 1 s, and the other conditions are the same, to obtain a hydrophilic surface S8 and a water collector sheet Q8.

[0149] Comparative Example 1

[0150] The method of Example 1 was followed, except that steps (1) to (2) were omitted, and a polypropylene sheet (foamed polypropylene sheet-1, water contact angle of 108°) was used as the hydrophilic surface DS1;

[0151] In step (3), the hydrophilic surface S1 is directly replaced with the hydrophilic surface DS1 to obtain the water collector sheet DQ1, and the water collector is assembled from the water collector sheet DQ1. The interval of the water collector sheet DQ1 is adjusted to 8 mm, so that the unit area porosity of the water collector sheet DQ1 is 40%.

[0152] Comparative Example 2

[0153] The method of Example 1 was followed, except that step (1) was omitted, and 10 parts by weight of maleic anhydride powder was directly coated on 100 parts by weight of a polypropylene sheet (foamed polypropylene sheet-1, water contact angle of 108°) by mechanical spraying to obtain a hydrophilic surface DS2;

[0154] In step (3), the hydrophilic surface S1 is directly replaced with the hydrophilic surface DS2 to obtain the water collector sheet DQ2, and the water collector is assembled from the water collector sheet DQ2. The interval of the water collector sheet DQ2 is adjusted to 7 mm, so that the unit area porosity of the water collector sheet DQ2 is 30%.

[0155] Comparative Example 2'

[0156] The method of Example 1 was followed, except that the foamed polypropylene sheet-1 was replaced by the injection-molded polypropylene sheet-1. Other conditions were the same, to obtain the hydrophilic surface DS2' and the water collector sheet DQ2'.

[0157] Comparative Example 3

[0158] The method of Example 2 was followed, except that step (1) was omitted, and 20 parts by weight of maleic anhydride powder was directly coated on 100 parts by weight of a polypropylene sheet (foamed polypropylene sheet-1, water contact angle of 108°) by mechanical spraying to obtain a hydrophilic surface DS3;

[0159] In step (3), the hydrophilic surface DS3 is directly used as the water collector sheet DQ3, and the water collector is assembled from the water collector sheets DQ3. The interval of the water collector sheets DQ3 is adjusted to 10 mm, so that the unit area porosity of the water collector sheets DQ3 is 50%.

[0160] Comparative Example 4

[0161] The method of Example 3 was followed, except that steps (1) to (2) were omitted, and a polypropylene sheet (foamed polypropylene sheet-2, water contact angle of 112°) was used as the hydrophilic surface DS4;

[0162] In step (3), the hydrophilic surface S3 is directly replaced with the hydrophilic surface DS4 to obtain the water collector sheet DQ4, and the water collector is assembled from the water collector sheet DQ4. The spacing of the water collector sheet DQ4 is adjusted to 12 mm, so that the unit area porosity of the water collector sheet DQ4 is 70%.

[0163] Comparative Example 5

[0164] The method of Example 3 was followed, except that step (1) was omitted. 30 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid powder was directly applied to 100 parts by weight of a polypropylene sheet (foamed polypropylene sheet-2, water contact angle of 112°) by mechanical spraying to obtain a hydrophilic surface DS5.

[0165] In step (3), the hydrophilic surface S3 is directly replaced with the hydrophilic surface DS5 to obtain the water collector sheet DQ5, and the water collector is assembled from the water collector sheet DQ5. The spacing of the water collector sheet DQ5 is adjusted to 12 mm, so that the unit area porosity of the water collector sheet DQ5 is 70%.

[0166] Comparative Example 5'

[0167] The method of Example 3 was followed, except that the foamed polypropylene sheet-2 was replaced by the injection-molded polypropylene sheet-2. Other conditions were the same, to obtain the hydrophilic surface DS5' and the water collector sheet DQ5'.

[0168] Comparative Example 6

[0169] The method of Example 4 was followed, except that steps (1) to (2) were omitted, and a polypropylene sheet (foamed polypropylene sheet-3, with a water contact angle of 108°) was used as the hydrophilic surface DS6;

[0170] In step (3), the hydrophilic surface S4 is directly replaced with the hydrophilic surface DS6 to obtain the water collector sheet DQ6, and the water collector is assembled from the water collector sheet DQ6. The interval of the water collector sheet DQ6 is adjusted to 20 mm, so that the unit area porosity of the water collector sheet DQ6 is 90%.

[0171] Comparative Example 7

[0172] The method of Example 4 was followed, except that step (1) was omitted, and 50 parts by weight of methacrylic acid liquid was directly applied to 100 parts by weight of a polypropylene sheet (foamed polypropylene sheet-3, water contact angle of 108°) by mechanical spraying to obtain a hydrophilic surface DS7;

[0173] In step (3), the hydrophilic surface S4 is directly replaced with the hydrophilic surface DS7 to obtain the water collector sheet DQ7, and the water collector is assembled from the water collector sheet DQ7. The interval of the water collector sheet DQ7 is adjusted to 20 mm, so that the unit area porosity of the water collector sheet DQ7 is 90%.

[0174] Comparative Example 7'

[0175] The method of Example 4 was followed, except that the foamed polypropylene sheet-3 was replaced by the injection-molded polypropylene sheet-3. Other conditions were the same, to obtain the hydrophilic surface DS7' and the water collector sheet DQ7'.

[0176] Comparative Example 8

[0177] According to the method of Example 5, except that step (1) is omitted, 40 parts by weight of vinyltrimethoxysilane liquid is applied to 100 parts by weight of a polypropylene sheet (foamed polypropylene sheet-3, water contact angle of 108°) by mechanical spraying to obtain a hydrophilic surface DS8;

[0178] In step (3), the hydrophilic surface S5 is directly replaced with the hydrophilic surface DS8 to obtain the water collector sheet DQ8, and the water collector is assembled from the water collector sheet DQ8. The interval of the water collector sheet DQ8 is adjusted to 20 mm, so that the unit area porosity of the water collector sheet DQ8 is 90%.

[0179] Table 1

[0180]

[0181] It can be seen from the data in Table 1 that, compared with the polypropylene sheet, the hydrophilic surface provided by the present invention effectively improves the hydrophilicity or even super-hydrophilicity of the hydrophilic surface while ensuring that the mechanical properties remain unchanged; at the same time, the water collector sheet containing the hydrophilic surface has a smaller water contact angle, a larger water recovery rate and a lower humidity. In particular, by adjusting the surface grafting rate parameters of the hydrophilic surface in the water collector sheet, the comprehensive performance of the water collector sheet containing the hydrophilic surface is further improved, thereby improving the water recovery rate of the water collector.

[0182] Compared with Example 6, Example 1 further improves the hydrophilic properties of the hydrophilic surface by limiting the weight ratio of the polypropylene sheet to the etchant within the preferred protection range, reducing the water contact angle and increasing the grafting rate, thereby effectively improving the water recovery rate of the water collector sheet containing the hydrophilic surface.

[0183] Compared with Example 7, Example 1 further improves the hydrophilic properties of the hydrophilic surface by limiting the weight ratio of the hydrophilic side group monomer and the modified polypropylene sheet within the preferred protection range and increasing the grafting rate, thereby effectively improving the water recovery rate of the water collector sheet containing the hydrophilic surface.

[0184] Compared with Example 8, Example 1 further improves the hydrophilic properties of the hydrophilic surface by limiting the microwave irradiation conditions within the preferred protection range, reducing the water contact angle and increasing the grafting rate, thereby effectively improving the water recovery rate of the water collector sheet containing the hydrophilic surface.

[0185] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A water collector, characterized in that: The water collector is assembled from water collector sheets, and the void ratio per unit area of ​​the water collector sheets is 10-90%; The water collector sheet material contains a hydrophilic surface, and the hydrophilic surface is a polypropylene sheet material having a micro-nano structure, and the micro-nano structure is grafted with hydrophilic side groups, and the micro-nano structure exists in the form of protrusions and / or grooves; Wherein, in the hydrophilic surface, the surface grafting rate of the hydrophilic side groups is 10-50wt%; Wherein, the polypropylene sheet is a foamed polypropylene sheet; the surface average pore size of the foamed polypropylene sheet is 10-100 μm, the bending strength is 0.1-1 MPa, and the thickness is 0.1-1 cm; The hydrophilic surface is prepared by the following method: contacting the polypropylene sheet with an etchant and performing a first drying to form a surface with a micro-nano structure on the polypropylene sheet to obtain a modified polypropylene sheet; coating the surface of the modified polypropylene sheet with a monomer having a hydrophilic side group, and then irradiating the surface with microwaves to graft hydrophilic side groups onto the micro-nano structure of the modified polypropylene sheet to obtain the hydrophilic surface; the contact conditions include: a temperature of 15-70°C and a time of 1-24 hours; the microwave irradiation conditions include: an irradiation power of 1500-27000 W and an irradiation time of 1 second to 1 minute.

2. The water collector according to claim 1, wherein: The water collector is assembled by water collector sheets at intervals of 3-50 mm through a skeleton; And / or, the void ratio per unit area of ​​the water collector sheet is 30-90%; and / or, after assembly, the shape of the water collector sheet is folded or serpentine; And / or, the water eliminator sheet includes a substrate and a hydrophilic surface supported on the substrate.

3. The water collector according to claim 1, wherein: The average pore size of the surface of the foamed polypropylene sheet is 20-60 μm; Flexural strength is 0.1-0.5 MPa; Thickness is 0.1-0.5cm; And / or, the foamed polypropylene sheet is made by foaming at least one selected from a homopolymer polypropylene sheet having a polypropylene content of ≥50wt%, a random copolymer polypropylene sheet, and an impact copolymer polypropylene sheet; And / or, the length of the micro-nanostructure is 1 nm-100 µm; the depth is 1 µm-1 mm.

4. The water collector according to claim 3, wherein: The length of the micro-nano structure is 500nm-50µm; the depth is 50-500µm.

5. The water collector according to claim 1, wherein: The water contact angle of the water collector sheet is less than 30°; the water recovery rate is greater than 50wt%; and the humidity is less than 90%; and / or, the hydrophilic side group is a side group containing a heteroatom of at least one element selected from oxygen, sulfur, nitrogen, silicon and halogen and a carbon-carbon double bond; And / or, the monomer of the hydrophilic side group is at least one selected from organic acid, organic acid derivative and vinyl silane.

6. The water collector according to claim 5, wherein: The water contact angle of the water collector sheet is 0-20°; the water recovery rate is 60-100wt%; and the humidity is less than 80%.

7. The water collector according to claim 6, wherein: The water contact angle of the water collector sheet is 0°.

8. A method for preparing a water collector, characterized in that: The method comprises the following steps: (1) contacting a polypropylene sheet with an etchant and performing a first drying process to form protrusions and / or grooves having a micro-nano structure on the polypropylene sheet, thereby obtaining a modified polypropylene sheet; the contacting conditions include: a temperature of 15-70° C. and a time of 1-24 hours; (2) coating the modified polypropylene sheet with a monomer having a hydrophilic side group, and then irradiating the modified polypropylene sheet with microwaves to graft the hydrophilic side group onto the micro-nanostructure of the modified polypropylene sheet to obtain a hydrophilic surface; the microwave irradiation conditions include: an irradiation power of 1500-27000 W; and an irradiation time of 1 second to 1 minute; (3) Assembling the water collector sheet containing the hydrophilic surface to obtain a water collector; Wherein, in the hydrophilic surface, the surface grafting rate of the hydrophilic side groups is 10-50wt%; Wherein, the polypropylene sheet is a foamed polypropylene sheet; the surface average pore diameter of the foamed polypropylene sheet is 10-100 μm, the bending strength is 0.1-1 MPa, and the thickness is 0.1-1 cm.

9. The method according to claim 8, wherein In step (1), the weight ratio of the polypropylene sheet to the etchant is 0.1-100:100; and / or, the etchant is a polar organic solvent selected from at least one of toluene, xylene, diphenyl ether, butyl acetate, isoamyl acetate, n-heptane, n-octane and decahydronaphthalene; And / or, the contacting is done by immersion.

10. The method according to claim 9, wherein: In step (1), the weight ratio of the polypropylene sheet to the etchant is 0.5-50:100; And / or, the etchant is at least one selected from toluene, xylene, diphenyl ether, butyl acetate, isoamyl acetate, n-heptane, n-octane and decahydronaphthalene.

11. The method according to claim 10, wherein: In step (1), the weight ratio of the polypropylene sheet to the etchant is 1-30:

100.

12. The method according to claim 8, wherein In step (2), the weight ratio of the hydrophilic side group monomer to the modified polypropylene sheet is 10-50:100; And / or, the microwave irradiation conditions include: irradiation power of 1500-15000 W; The irradiation time is 1-30 s.

13. The method according to claim 12, wherein: In step (2), the weight ratio of the hydrophilic side group monomer to the modified polypropylene sheet is 10-30:

100.

14. The method according to claim 8, wherein In step (3), the assembling method includes: assembling the water collector sheets through a skeleton at intervals of 3-50 mm.

15. The method according to any one of claims 8 to 14, wherein: The method further comprises: before the assembling, washing and second drying the microwave irradiated product; And / or, the method further includes: when the monomer of the hydrophilic side group is an organic acid, an anhydride and / or ester of an organic acid, subjecting the second dried product to a salification reaction with a base, and washing and thirdly drying the product of the salification reaction.

16. The method according to claim 15, wherein The base is selected from hydroxide and / or ammonia; and / or, the weight ratio of the alkali to the modified polypropylene sheet is 10-25:100; And / or, the alkali exists in the form of alkali solution, and the weight ratio of the alkali to water in the alkali solution is 0.1-100:

100.

17. The method according to claim 16, wherein The base is a hydroxide; and / or, the weight ratio of the alkali to the modified polypropylene sheet is 10-20:100; And / or, in the alkali solution, the weight ratio of alkali to water is 0.5-50:

100.

18. The method according to claim 17, wherein In the alkali solution, the weight ratio of alkali to water is 1-30:

100.

19. A cooling tower, characterized in that: The interior of the cooling tower is provided with the water collector according to any one of claims 1 to 7, or the water collector made by the method according to any one of claims 8 to 18.

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