Filtering material, preparation method thereof and filtering device

Abstract

The invention relates to the technical field of novel filtering materials for air purification, in particular to a filtering material, a preparation method thereof and a filtering device. The filter material is composite glass fiber filter paper and sequentially comprises a first waterproof breathable cloth layer, a glass fiber filter paper layer set and a second waterproof breathable cloth layer in the thickness direction, interfaces on the two sides are bonded in a point-shaped or grid-shaped discontinuous mode through moisture curing reaction type polyurethane hot melt adhesive PUR, and the adhesive layer coverage rate and the adhesive applying amount per unit area are controlled. And an encapsulating edge sealing area is arranged in the circumferential direction of the material, so that the waterproof breathable cloth on the two sides is subjected to hot-pressing fusion and / or continuous PUR bonding at the edge to encapsulate the cut edge of the glass fiber layer group. According to the structure, liquid water and the edge can be prevented from permeating into a channel, sudden increase of resistance caused by swelling and hole blocking of an adhesive layer in a humid environment is inhibited, the interlayer bonding retention rate and the damp-heat stability are improved, and the folded sharp corner forming quality and the machining yield are remarkably improved through the outer layer force bearing protection glass fiber layer set.

Description

Technical Field

[0001] This invention relates to the field of novel air purification filter materials, and in particular to a filter material, its preparation method, and filter device. Background Technology

[0002] Filter media are key materials used to separate impurities from fluids such as air, water, and oil. They typically utilize the pore size gradient and specific surface area formed by fiber networks or porous structures to remove particulate matter, smoke, aerosols, microorganisms, and some gaseous pollutants through mechanisms such as physical interception, inertial collision, diffusion capture, electrostatic adsorption, and surface adsorption. With the increasing demand for clean air and high-purity media in industries such as clean manufacturing, public health protection, new energy, and automobiles, filter materials not only need to have high filtration efficiency and high dust holding capacity, but also need to maintain stable flux and low resistance over long periods under complex environments (high humidity, temperature fluctuations, corrosive media, vibration, and pulsating airflow, etc.), while meeting requirements for processability (such as pleating) and reliability.

[0003] In the field of air purification, high-efficiency particulate air (HEPA) and ultra-high-efficiency particulate air (ULPA) filters often use filter paper or filter media with glass fiber as the main component. Glass fiber materials have advantages such as being non-flammable, heat-resistant, corrosion-resistant, and having good dimensional stability. Moreover, ultra-fine glass fibers can form a dense three-dimensional fiber network, enabling the filter media to achieve high filtration efficiency with a low basis weight. However, fiberglass materials also have significant challenges in engineering applications: First, fiberglass itself is hydrophilic but does not absorb water. In humid or hot environments, moisture is more likely to migrate on the fiber surface and in the pores between fibers. Second, wet-processed fiberglass filter paper usually requires adhesives / bonding resins to improve paper strength. However, common thermal self-crosslinking resins or hot melt adhesives may swell or experience a decline in mechanical properties after absorbing moisture, leading to pore blockage, a sharp increase in pressure drop, and even local structural collapse. Third, fiberglass filter paper is brittle and has insufficient folding resistance. During folding, fiber breakage or micro-crack propagation can easily occur at the folds, making it difficult to form sharp folds, reducing the yield, and ultimately affecting the effective filtration area, resistance, and service life of the filter.

[0004] Several solutions exist in the prior art for improving the strength and composite reinforcement of glass fiber filter paper. For example, patent document (CN2522453Y) discloses a high-efficiency air filter paper for passenger compartments, which uses glass fiber as the main filter layer and sets reinforcement layers on both sides, and is compositely bonded by hot melt adhesive. This aims to balance filtration efficiency and mechanical strength, and meet the application requirements of automotive air conditioning systems. This type of technology can improve the tensile and burst resistance of glass fiber filter paper to a certain extent through double-sided reinforcement layers and adhesive bonding. However, its reinforcement layers are mostly conventional non-woven fabrics, and the reinforcement layers themselves are not designed to block liquid and allow air to pass through. At the same time, hot melt adhesives are mostly thermoplastic adhesive systems. When facing long-term high humidity or condensation environments, there is still a risk that the adhesive layer may absorb moisture, the interfacial adhesion may weaken, or the pores may be affected by the adhesive layer / moisture, resulting in increased resistance. Furthermore, double-sided reinforcement cannot structurally block the path of moisture migration from the surface or edge of the filter material into the interior of the fiberglass layer. In particular, weak channels for moisture entry may be formed at the cut edges and fold roots of the pleated filter material, leading to performance fluctuations in humid and hot environments.

[0005] To reduce the negative impact of composite adhesive layers on pore structure and airflow resistance, some solutions optimize the morphology of the adhesive layer. Patent document CN2309876Y discloses a high-strength composite filter paper, which sets an adhesive layer between a glass fiber filter paper substrate and a composite material layer, designing this adhesive layer as an irregular dotted structure. The composite material layer can be non-woven fabric, glass fiber cloth, or other fabrics. The dotted adhesive layer approach helps reduce pore clogging problems caused by continuous adhesive films and, to some extent, balances strength and flux. However, this type of technology mainly focuses on the trade-off between resistance and strength caused by the adhesive layer morphology, and does not establish a systematic water-blocking strategy for the failure mechanisms of glass fiber filter paper under high humidity environments, such as adhesive layer swelling, pore blockage, interface loss of adhesion, and even structural collapse caused by moisture migration. In other words, even with a dotted adhesive layer, if the composite system still allows liquid water or high-humidity water vapor to continuously enter the interface between the glass fiber layer and the adhesive layer, the adhesive system and the glass fiber layer pores may still experience performance drift under humid and hot conditions, making it difficult to guarantee the long-term stability of filtration resistance. Meanwhile, this type of solution does not address specific structural protection and reliability designs for issues such as the ability to form sharp corners during pleating, the suppression of fiber breakage at creases, and stress distribution at the root of pleats.

[0006] In summary, while existing technologies have explored aspects such as composite reinforcement of glass fiber filter paper and dotted adhesive layer morphology to reduce the risk of pore blockage, they still have the following shortcomings: First, most existing double-sided reinforced composite filter papers do not structurally achieve an outer barrier that blocks liquid and allows air to pass through, making it difficult to prevent liquid water or moisture in high-humidity environments from entering the interior of the glass fiber layer at the source. This makes it difficult to avoid abnormal increases in resistance and degradation of filtration performance under humid and hot conditions. Second, existing dotted adhesive layer solutions primarily serve to reduce pore blockage, but lack a systematic design for interface failure paths and edge penetration channels in humid environments, making it difficult to balance long-term low-resistance stability and high reliability. Therefore, there is an urgent need to provide a novel glass fiber filter material and its preparation method for air purification applications, which can maintain stable filtration resistance and structural strength in high-humidity environments and improve the ability and reliability of pleating and sharp corner forming, thereby meeting the needs of more demanding operating conditions and industrial manufacturing. Summary of the Invention

[0007] The technical objective of this invention is to provide a composite glass fiber filter material suitable for air purification and other fields, and its preparation method. By composited liquid-resistant and breathable waterproof fabric on both sides of the glass fiber filter paper layer and using a moisture-curing reactive PUR adhesive in a specific sizing method to achieve stable bonding, the invention solves the problems of existing glass fiber filter paper clogging, sharp increase in resistance, and structural failure caused by moisture absorption and swelling of the adhesive layer in humid environments. At the same time, it improves the tear resistance and sharp corner forming quality during the pleating process, thereby improving the processing yield and service reliability of the filter material.

[0008] Firstly, in order to achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A filter material, wherein the filter material is a composite glass fiber filter paper laminated along the thickness direction, comprising, in sequence, a first waterproof and breathable cloth layer, a glass fiber filter paper layer assembly, and a second waterproof and breathable cloth layer.

[0010] A first adhesive layer is provided between the first waterproof and breathable fabric layer and the glass fiber filter paper layer assembly, and a second adhesive layer is provided between the second waterproof and breathable fabric layer and the glass fiber filter paper layer assembly; both the first adhesive layer and the second adhesive layer are formed by moisture-curing reactive polyurethane hot melt adhesive (PUR).

[0011] Both the first and second adhesive layers have a discontinuous dotted or grid-like coating structure, with an adhesive coverage of 10%–40%; the adhesive application rate per unit area of ​​the first and second adhesive layers is 2.0–2.5 g / m². 2 ;

[0012] The glass fiber filter paper layer assembly comprises 1–3 layers of glass fiber filter paper;

[0013] Both the first and second waterproof and breathable fabric layers are formed by ES composite fibers. The ES composite fibers are core-sheath structure fibers with a core component of polypropylene and a sheath component of polyethylene. The fineness of the ES composite fibers is 0.5–30 denier.

[0014] Preferably, the fineness of the ES composite fiber is 1–20 denier;

[0015] And / or, the number of layers in the glass fiber filter paper layer assembly is 1–2;

[0016] And / or, the adhesive layer coverage is 15%–30%;

[0017] And / or, the equivalent diameter of a single point of the dotted coating structure is 0.2–1.5 mm, and the center distance between adjacent points is 0.5–5 mm.

[0018] Preferably, at least the outer surface of the first waterproof and breathable fabric layer and the second waterproof and breathable fabric layer has a water-repellent finishing layer or a water-repellent material coating.

[0019] Preferably, the glass fiber filter paper is wet-processed glass fiber filter paper and contains a thermally self-crosslinking resin adhesive, which is an acrylic or polyurethane adhesive.

[0020] Preferably, the circumferential edge of the filter material is provided with an encapsulation sealing area, the width of which is 2–15 mm; within the encapsulation sealing area, the first waterproof and breathable fabric layer and the second waterproof and breathable fabric layer are bonded together by hot pressing and / or continuous PUR bonding to encapsulate the edge of the glass fiber filter paper layer assembly.

[0021] Secondly, the present invention also provides a filter element comprising the aforementioned filter material, wherein the filter material is folded into a pleated structure to form a filter channel.

[0022] Preferably, the crease lines of the pleated structure are parallel to the long side of the filter material, and the sealing area is located at the two edges of the pleated structure.

[0023] Thirdly, the present invention also provides a method for preparing the filter material, the method comprising:

[0024] Provides a first waterproof and breathable fabric layer, a second waterproof and breathable fabric layer, and a fiberglass filter paper layer assembly comprising multiple layers of fiberglass filter paper;

[0025] After melting, the moisture-curing reactive polyurethane hot melt adhesive (PUR) is applied to the first and second composite interfaces in a dotted or grid pattern, ensuring that the adhesive application rate per unit area for each composite interface is 2.0–2.5 g / m². 2 And the adhesive layer coverage meets the requirement of 10%–40%;

[0026] The first waterproof and breathable fabric layer, the fiberglass filter paper layer, and the second waterproof and breathable fabric layer are bonded and pressurized together to form a first adhesive layer and a second adhesive layer.

[0027] The circumferential edges of the composite material are sealed by heat pressing and / or continuous PUR sealing, so that the first waterproof and breathable fabric layer and the second waterproof and breathable fabric layer are bonded to each other in the sealing area to seal the edge of the fiberglass filter paper layer group, forming a sealing area with a width of 2–15 mm.

[0028] Preferably, after lamination, the PUR is subjected to a moisture curing reaction under the action of ambient humidity, so that the first adhesive layer and the second adhesive layer form a cross-linked cured structure.

[0029] Preferably, the method further includes: pleating the filter material after forming the sealing edge area to obtain a pleated filter material for a paper-folding filter.

[0030] This invention employs a waterproof and breathable fabric layer that blocks liquid and allows air to pass through on both sides of a glass fiber filter paper layer assembly. A moisture-curing reactive PUR hot melt adhesive is used to achieve a composite bond with controlled application and a dotted / grid-like bonding method, simultaneously forming a circumferentially encapsulated edge zone. This synergistic approach inhibits moisture ingress and pore blockage through both structural and interfacial pathways: First, the waterproof and breathable fabric layer prevents liquid water and condensate from directly penetrating the glass fiber layer during use, significantly reducing the probability of moisture absorption by the glass fiber layer and adhesive interface. Second, the PUR adhesive undergoes chemical curing under moisture, forming a stable cross-linked network. A small amount of moisture is absorbed and participates in the curing reaction, mechanistically avoiding the micropore blockage and adhesion problems caused by moisture absorption and swelling of conventional self-crosslinking resins or ordinary hot melt adhesives. The invention addresses several key aspects of filter technology. First, it addresses the issue of moisture failure, ensuring the filter material maintains low and stable filtration resistance and flux even under high humidity / humid heat conditions. Second, it utilizes dotted / grid bonding and limited adhesive application to reduce the risk of continuous membrane clogging, improving interlayer strength while preserving the effective pore structure and high dust holding capacity of the fiberglass filter layer. Third, it employs circumferential sealing to block water seepage channels at the cut edges and fold roots, further enhancing structural integrity and durability under humid heat conditions. Fourth, it incorporates waterproof and breathable fabric layers on both sides to provide load-bearing and folding protection, ensuring that fold stress during folding is primarily borne by the outer layer, significantly reducing the risk of fiber breakage and fiber shedding at folds. This results in sharper, more stable fold corners and improves the yield rate and assembly consistency of the filter. In summary, this invention achieves a comprehensive performance improvement in terms of resistance to moisture failure, low resistance stability, foldability, and high reliability without sacrificing filtration efficiency. This significantly extends the effective service life of the filter under high humidity fluctuations and reduces maintenance and replacement costs. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, those skilled in the art should understand that the following embodiments are used to illustrate the present invention and not to limit the scope of protection; without departing from the limitations of the present invention, equivalent substitutions or conventional adjustments to the source of raw materials, equipment models, processes and testing conditions should still fall within the scope of protection of the present invention.

[0032] I. Terminology and Parameter Definitions

[0033] To facilitate understanding and implementation, this document defines key terms and parameters as follows:

[0034] Waterproof and breathable fabric layer: refers to a nonwoven fabric layer formed by weaving and reinforcing hydrophobic synthetic fibers, which satisfies the liquid-blocking and breathable characteristics that prevent liquid water from penetrating under normal operating pressure differentials, while allowing gas to pass through. In the embodiments, ES composite fiber nonwoven fabric is preferred.

[0035] ES composite fiber: refers to core-sheath composite fiber, with the core component being polypropylene (PP) and the sheath component being polyethylene (PE). The lower melting point of the sheath layer is used to achieve thermal bonding and reinforcement.

[0036] Glass fiber filter paper: refers to filter paper substrate made of ultra-fine glass fiber as the main fiber component and formed by wet papermaking. It may contain a small amount of thermal self-crosslinking resin to improve the strength of the paper.

[0037] Fiberglass filter paper layer assembly: refers to the collection of fiberglass filter paper layers located in the middle of the composite material, including... Glass fiber filter paper, Integer and .

[0038] PUR adhesive (moisture-curing reactive polyurethane hot melt adhesive): refers to a polyurethane hot melt adhesive system that has rapid initial adhesion after being applied in a heated and molten state, and then undergoes a chemical reaction with ambient moisture to cure and cross-link.

[0039] Application rate per unit area This refers to the ratio of the mass of PUR adhesive applied to a single composite interface to the area of ​​that interface, expressed in g / m². ;in, The amount of adhesive applied to this interface (g). The area of ​​this interface (m²) 2 This invention is limited to g / m 2 .

[0040] Adhesive layer coverage The ratio of the projected area of ​​the adhesive layer to the area of ​​the composite interface is defined as follows: ;in, This represents the projected area of ​​the glue dots / glue screen on the interface. The total area of ​​the interface; this invention limits... .

[0041] Encapsulation edge width : Refers to the encapsulation width along the circumferential edge of the filter media, in mm. This invention limits... mm, and the waterproof and breathable fabrics on both sides of the sealing area are bonded together by hot pressing and / or continuous PUR bonding to seal the edge of the fiberglass layer assembly.

[0042] Pleated corner forming ability: refers to the ability of filter material to form stable pleated corners during pleating process without damage or fiber loss at the pleats. The example is characterized by pleating yield, pleat crack / fiber breakage rate and corner radius.

[0043] Damp heat aging: refers to the accelerated aging process carried out in a constant temperature and humidity chamber. The example uses... , Conditional aging for 24 hours or 7 days is used to evaluate resistance stability and bond retention rate.

[0044] II. Raw Materials, Equipment, and General Preparation Routes

[0045] (a) Raw materials

[0046] 1. Fiberglass filter paper (middle layer)

[0047] Glass fiber diameter: .

[0048] Quantitative (basic weight): (Commonly used in the examples) ).

[0049] thickness: (Varies depending on the quantity and pressure).

[0050] Contains adhesive resin: May contain acrylic or polyurethane thermo-self-crosslinking resin. (mass fraction) to ensure paper strength and fiber consolidation.

[0051] Fiberglass filter paper is prone to increased resistance in high humidity environments due to moisture absorption by the adhesive layer and local blockage of the pores, and it is also prone to tearing at creases. This is precisely the problem that this invention aims to solve.

[0052] 2. Waterproof and breathable fabric (outer layer, preferably ES fiber nonwoven fabric)

[0053] Fiber: ES core-sheath fiber (PP core / PE sheath).

[0054] Fineness : Dan (Multiple Examples) dawn).

[0055] Quantitative: (Multiple examples) ).

[0056] Reinforcement methods: hot rolling / hot air penetration / spot bonding, etc. (hot pressing spot bonding can be simulated in the laboratory).

[0057] Optional surface water-repellent finishing: silane / long-chain alkyl finishing agents or fluorine-free water-repellent agents, finishing amount .

[0058] The outer layer acts as a liquid barrier and air permeable layer to prevent liquid water or condensation from entering the middle fiberglass layer. At the same time, the outer layer bears the main bending stress during the folding process, protecting the fiberglass layer assembly.

[0059] 3. PUR moisture-curing reactive polyurethane hot melt adhesive

[0060] Softening point / coating temperature: (Varies depending on the recipe).

[0061] Melt viscosity: ( ).

[0062] Typical curing conditions: room temperature , The main moisture curing is completed after 24 hours, and it tends to be fully cured after 7 days.

[0063] The key to PUR is that a small amount of moisture can participate in the curing and cross-linking process, reducing the probability of traditional adhesives swelling and failing under humid conditions.

[0064] (II) Main Equipment

[0065] 1. Small PUR hot melt adhesive melting machine (with temperature control, stable glue output).

[0066] 2. Dot / mesh coating device:

[0067] Option A: Engraving gravure roller (anilox roller) + doctor blade metering (can achieve dot matrix / grid).

[0068] Option B: Pulse spray adhesive valve + motion platform (to achieve regular dot matrix).

[0069] 3. Composite pressing device: Flat plate hot press or small roller pressing composite machine (pressure) Adjustable).

[0070] 4. Edge sealing device: Narrow-width hot-press edge sealing mold (width) (Mold changeable).

[0071] 5. Constant temperature and humidity chamber ( , ).

[0072] 6. Performance testing equipment:

[0073] Pressure drop / resistance test: differential pressure gauge + air volume control (or filter media resistance test bench).

[0074] Filtration efficiency test: NaCl aerosol generator + particle counter (common laboratory conditions are around 0.3μm or MPPS).

[0075] Peel strength: Universal testing machine (180° peel).

[0076] Tensile strength: Universal testing machine.

[0077] Air permeability: Fabric air permeability meter (e.g., built according to ASTM D737).

[0078] Folding test: Small paper folding machine / manual folding fixture + sharp corner radius measurement (projector or microscope).

[0079] III. General Preparation Method

[0080] To enable those skilled in the art to implement this without inventive effort, a set of general and quantifiable preparation steps is provided. The embodiments are based on this, with only variations in parameters within a specified range.

[0081] S1: Material pretreatment and cutting

[0082] Cut the first waterproof and breathable fabric layer (outer layer A), the fiberglass filter paper layer assembly (middle layer B), and the second waterproof and breathable fabric layer (outer layer C) to the target dimensions. The fiberglass filter paper layer assembly is cut according to... Stack them on top of each other, aligning the edges; if It can be positioned in very slight dots between layers (not included in the PUR sizing amount) to prevent displacement. If the outer waterproof and breathable fabric contains a water-repellent finishing layer, the finishing layer must be facing outwards (away from the fiberglass layer group) to enhance the water repellency and stain resistance of the outer surface.

[0083] S2: PUR melt coating with dotted / mesh application

[0084] 1. Add PUR hot melt adhesive to the glue melting machine and set the temperature. (Adjust according to the viscosity of the adhesive) ).

[0085] 2. Choose either dot or grid coating method and control the adhesive layer coverage. With the amount of adhesive applied :

[0086] Dotted coating: the equivalent diameter of the dots Center distance of points ;pass and Combinatorial implementation .

[0087] Mesh coating: line width Grid spacing Controlling projection coverage .

[0088] 3. Coating Target: PUR can be coated at the interface between the first waterproof and breathable fabric and the fiberglass layer assembly (interface 1) and at the interface between the fiberglass layer assembly and the second waterproof and breathable fabric (interface 2). In laboratory operations, it is preferable to apply the adhesive dots to the inner surface of the outer fabric (the side closest to the fiberglass) to facilitate dot matrix formation and measurement.

[0089] 4. Application amount Measurement and calibration:

[0090] Take area (For example The outer layer of fabric sample was weighed before coating. Weigh immediately after coating. The quality of the adhesive application at the interface ;calculate By adjusting the anilox roller volume, doctor blade gap, glue spraying frequency, or coating speed, Stable at .

[0091] Note: To reduce errors, weighing should be completed within 1 minute after coating to avoid stringing loss before the adhesive dots cool; each calibration should be repeated at least 3 times and the average value should be taken.

[0092] 5. Coverage Determination method:

[0093] Add to PUR before coating A trace amount of inert pigment (such as titanium dioxide or carbon black) by mass fraction is used for contrast development (without affecting curing); after coating, an interface projection image is taken (by fixed-distance photography or scanning), and the projected area of ​​the adhesive dots is calculated using image binarization software. With total area ,get Adjust the lattice parameters until... satisfy .

[0094] S3: Lamination and Pressure Shaping

[0095] 1. Place the first waterproof and breathable fabric layer coated with PUR on the laminating table with the adhesive dots facing upwards;

[0096] 2. Align and place the fiberglass filter paper layer on top;

[0097] 3. Cover the fiberglass layer with the second waterproof and breathable fabric layer (adhesive can be applied first and then stacked) to form an A / B / C sandwich structure;

[0098] 4. Entering the composite pressing stage:

[0099] Flat plate hot pressing: temperature (To avoid excessive melting of the outer layer causing pore closure), pressure Holding time ;

[0100] Roller pressing: Roller temperature Linear pressure linear velocity .

[0101] Note: The goal of lamination is to fully wet the fiber structure on both sides of the adhesive dots and form an initial bond, rather than forming a continuous adhesive film; after lamination, it should be observed that the adhesive dots mechanically interlock between the fibers rather than spreading into a film.

[0102] S4: Formation of the circumferentially enclosed edge area

[0103] 1. A sealing edge area is set around the four edges of the composite sheet, with a width of... (Commonly used in the examples) ).

[0104] 2. Edge sealing methods are optional:

[0105] Hot-press fusion sealing: Utilizing the low melting point of the ES fiber lining PE, a narrow hot-press die is used to hot-press the edge strip area, directly fusing the waterproof and breathable fabrics on both sides at the edge; Typical conditions: , , .

[0106] Continuous PUR edge sealing: Apply a continuous PUR strip (width) along the circumferential edge. Then heat and press together; this method is suitable for occasions where the airtightness / watertightness requirements of the edge sealing are higher.

[0107] 3. The edge after sealing should have a continuous strip-shaped bonding / fusion structure, so that the cut edge of the fiberglass layer is covered by the outer layer of cloth on both sides, blocking the edge water seepage channel.

[0108] S5: Moisture Curing and Maintenance

[0109] Place the composite and sealed filter material into , Allow to stand for 24 hours under the given conditions to complete the main moisture curing; if extreme moisture and heat resistance testing is required, continue to leave for 7 days or... , Accelerated curing was carried out for 48 hours under the specified conditions. After curing, cutting and subsequent folding processing tests were conducted.

[0110] IV. Examples

[0111] Example 1 (Base Example)

[0112] 1. Materials

[0113] Fiberglass filter paper: basis weight ,thickness Number of layers .

[0114] Waterproof and breathable fabric: ES fiber hot air fabric, basis weight , fineness Dan, with fluorine-free water-repellent finish on the outer surface .

[0115] PUR adhesive: Moisture-curing reactive polyurethane hot melt adhesive, coating temperature .

[0116] 2. Coating parameters

[0117] Dot-matrix coating, equivalent diameter of adhesive dots Center distance of points ;

[0118] Coverage ;

[0119] Single-interface application rate (Both interfaces are version 2.2).

[0120] 3. Lamination and edge banding

[0121] Flat plate hot pressing composite: , , ;

[0122] Hot-pressed edge sealing: , , , ;

[0123] Maintenance: , , 24h.

[0124] 4. Test Results (Average, n=5)

[0125] initial pressure drop Filtration efficiency ;

[0126] After 24 hours of hot and humid weather: , ;

[0127] After 7 days of hot and humid weather: , ;

[0128] Initial stripping ; 7 days later , ;

[0129] Folding yield ; radius of sharp corner ;

[0130] Water seepage at the edges: The cut surface of the fiberglass layer is dry and there is no dye penetration.

[0131] Note: Example 1 demonstrates the synergistic effect of liquid-resistant and breathable outer layer + PUR dotted low-volume bonding + edge sealing. The pressure drop increase after humid heat is small, and the folded corners are stable.

[0132] Example 2

[0133] Differences from Example 1:

[0134] Coverage (by increasing the point spacing) ,Keep accomplish);

[0135] Maintain the amount of adhesive applied ;

[0136] Edge sealing Unchanged; number of fiberglass layers constant.

[0137] Test results (n=5):

[0138] , ;

[0139] 7 days of hot and humid weather: , ;

[0140] Peel retention rate ;

[0141] Folding yield ; ;

[0142] Edge seepage .

[0143] Note: When As the resistance approaches the lower limit, the initial resistance decreases slightly due to the more dispersed adhesive dots; as long as It remains at 2.0–2.5 g / m² with effective edge sealing, and its humid heat stability is maintained.

[0144] Example 3

[0145] Differences from Example 1:

[0146] Coverage (By reducing the point spacing) , point diameter accomplish);

[0147] Application amount ;

[0148] Number of fiberglass layers (Reduce base weight to balance resistance);

[0149] Edge sealing .

[0150] Test results:

[0151] , ;

[0152] 7 days of hot and humid weather: , ;

[0153] , ;

[0154] Folding yield , ;

[0155] .

[0156] Note: In When approaching the upper limit, if the point / mesh discontinuous structure is still maintained and Controlling the concentration at 2.0–2.5 g / m² prevents continuous membrane pore blockage; simultaneously This further reduces the resistance, indicating that the present invention can achieve essentially consistent moisture resistance stability under different combinations of the number of layers.

[0157] Example 4

[0158] Differences from Example 1:

[0159] Mesh coating method: line width Grid spacing ;

[0160] Coverage Application amount ;

[0161] Number of fiberglass layers (Upper limit);

[0162] Edge sealing (Enhanced edge encapsulation).

[0163] Test results:

[0164] , ;

[0165] 7 days of hot and humid weather: , ;

[0166] ;

[0167] Folding yield , ;

[0168] .

[0169] Note: When The initial resistance increase is normal, but the increase in humidity and heat is still at a low level; the grid structure provides a continuous support frame while ensuring bonding strength, and is also beneficial for folding processing.

[0170] Example 5

[0171] Differences from Example 1:

[0172] Waterproof and breathable fabric fiber density Dan, quantitative ;

[0173] , , ;

[0174] Edge sealing The hot pressing conditions are the same as in Example 1.

[0175] Test results:

[0176] , ;

[0177] 7 days of hot and humid weather: , ;

[0178] ;

[0179] Folding yield , (Sharper angles);

[0180] .

[0181] Note: Fine denier ES fabric is smoother and easier to form sharp pleats; at the same time, the outer layer has more uniform pores, which helps to maintain low resistance.

[0182] Example 6

[0183] Differences from Example 1:

[0184] Waterproof and breathable fabric fiber density Dan, quantitative ;

[0185] , , ;

[0186] Edge sealing .

[0187] Test results:

[0188] , ;

[0189] 7 days of hot and humid weather: , ;

[0190] ;

[0191] Folding yield , (The sharp corner has become blunt but is still acceptable);

[0192] .

[0193] Note: The coarse denier outer layer increases the overall hardness of the material and the radius of sharp corners, but it is still within the usable range; the key is that the outer layer is still an ES hydrophobic system and the composite / edge sealing structure is correct, so the humid heat stability remains.

[0194] Example 7

[0195] Differences from Example 1:

[0196] Encapsulation and sealing area (Lower limit);

[0197] Other parameters: , , , dawn.

[0198] Test results:

[0199] 7 days of hot and humid weather: , ;

[0200] Edge seepage (significantly higher than Example 1);

[0201] Folding yield .

[0202] illustrate: Too small a value will reduce the water-blocking redundancy of the sealing edge, increase the length of edge seepage, and slightly increase the pressure drop after humid heat; however, it is still significantly better than the comparative example (see below). This example suggests that it is preferred when the target operating conditions are more severe. mm is more stable.

[0203] Example 8

[0204] Differences from Example 1:

[0205] (Upper limit);

[0206] , , , dawn.

[0207] Test results:

[0208] (Increasing the edge width has a slight impact on the effective ventilation area.) ;

[0209] 7 days of hot and humid weather: , ;

[0210] ;

[0211] .

[0212] Note: Increased edge sealing width significantly reduces edge water seepage and the increase in damp heat pressure drop, making it suitable for high humidity and condensation conditions.

[0213] V. Comparative Examples

[0214] Comparative Example 1 (glass fiber filter paper only: no outer water-blocking layer, no PUR composite)

[0215] Structure: Individual glass fiber filter paper It is not composite with the outer layer and is not edge-sealed.

[0216] test: After 7 days of hot and humid weather , ;

[0217] Observation: The surface of the fiberglass layer is visibly damp, with localized blockage of pores and a tendency to collapse in some areas; the yield rate of pleated finished products is only [percentage missing]. (Significant creases, tears, and fiber shedding).

[0218] Conclusion: This shows that glass fiber filter paper alone is insufficient to meet the requirements for high humidity stability and folding processing.

[0219] Comparative Example 2 (D1 type structure: double-sided ordinary non-woven fabric + conventional hot melt adhesive continuous film composite)

[0220] Outer layer: Ordinary PET fiber nonwoven fabric, basis weight (Non-liquid-resistant and breathable design).

[0221] Adhesive: EVA hot melt adhesive, applied using a continuous coating method (coverage approximately...) ), amount of adhesive applied .

[0222] No edge banding ( ).

[0223] test: After 7 days of hot and humid weather , ;

[0224] Peel retention rate ; Folding yield Water seepage at the edges .

[0225] Conclusion: Continuous adhesive films are more prone to clogging pores, and ordinary hot melt adhesives have poor adhesion retention after being exposed to moisture and heat; when there is no water-blocking outer layer and edge sealing, water seepage at the edges is obvious, leading to increased resistance.

[0226] Comparative Example 3 (using PUR but continuous film coating: loss of key dotted / mesh discontinuity features)

[0227] Outer layer: ES waterproof and breathable fabric (same as in Example 1).

[0228] Adhesive: PUR, but applied using a continuous coating method. , .

[0229] Edge sealing: .

[0230] test: (Significantly increased); after 7 days of hot and humid weather , ; Folding yield .

[0231] Conclusion: Even with PUR, continuous membranes significantly increase initial resistance and reduce flux; this underscores the necessity of the dotted / grid discontinuous coating + coverage control method of this invention.

[0232] Comparative Example 4 (Application amount exceeds the upper limit:) (Excessive size may lead to clogging)

[0233] The structure is the same as in Example 1, but the amount of adhesive applied is increased to (Outside the scope of the claims), coverage .

[0234] test: After 7 days of hot and humid weather , ;

[0235] Observation: The adhesive dots obviously collapsed and spread out, and some areas were semi-continuous films, resulting in a reduction in effective porosity.

[0236] Conclusion: Excessive application of adhesive causes pore blockage and increased resistance, proving that... The importance of process control for achieving a balance between low resistance and high strength.

[0237] Comparative Example 5 (Unsealed edge area: only composite without edge sealing, verifying the water-blocking value of edge sealing)

[0238] The structure is the same as in Example 1, but without edge sealing. ).

[0239] test: After 7 days of hot and humid weather , ;

[0240] Edge seepage The fiberglass layer on the cut surface shows a damp zone; the yield rate of folded products is low. (Processing is still good, but moisture resistance has deteriorated significantly).

[0241] Conclusion: Edge sealing is one of the key structural features for suppressing edge seepage channels; without edge sealing, the increase in hygrothermal resistance is significantly greater.

[0242] Comparative Example 6 (Outer layer fineness exceeds the upper limit:) (leading to differences in the sharp angles of the folds)

[0243] Outer layer: ES fiber, but fineness Dan (beyond the scope of the claims), quantitative ;

[0244] The rest is the same as in Example 1 ( , , , ).

[0245] Test: Damp heat stability is acceptable. However, the yield rate of pleated finished products is low. Sharp corner radius The folds rebound severely at the root, making it difficult to form stable sharp corners.

[0246] Conclusion: An overly stiff outer layer makes pleating difficult, proving that... The upper limit setting is related to the forming of sharp corners.

[0247] Comparative Example 7 (glass fiber layer count exceeds the limit): This leads to excessive resistance and exacerbates sensitivity to heat and humidity.

[0248] Intermediate fiberglass layer assembly: (Beyond the scope of the claims), the remaining parameters are the same as in Example 1.

[0249] test: After 7 days of hot and humid weather , ; fiberglass is more prone to breakage at the root of the folds during pleating, resulting in a lower yield. .

[0250] Conclusion: Excessive layers increase resistance and processing risks, and also make the pressure drop after humid heating more pronounced, reflecting... The engineering significance of upper limit restrictions.

[0251] Comparative Example 8 (outer layer is general hydrophobic PP nonwoven fabric but not ES structure: difficult to seal edges and poor interface retention)

[0252] Outer layer: Ordinary PP spunbond nonwoven fabric (non-ES core-sheath structure), basis weight ;

[0253] Adhesive: PUR dot coating ( , );

[0254] It is difficult to achieve hot-press fusion for edge sealing, and can only rely on continuous PUR edge sealing. Hard edges and warping are prone to occur in the edge sealing area.

[0255] Test: After 7 days of humid heat The hard edge during folding causes localized stress concentration. .

[0256] Conclusion: The ES core-sheath structure is more conducive to hot-pressing edge sealing and improves edge sealing consistency; this comparison demonstrates the rationality of selecting ES fibers.

[0257] VI. Summary and Comparison of Examples and Comparative Cases

[0258] (a) Test Samples and Grouping

[0259] 1. Sample structure and key parameters

[0260] The sample of this invention has a sandwich composite structure: outer layer A (waterproof and breathable fabric) / middle layer B (glass fiber filter paper layer) / outer layer C (waterproof and breathable fabric). Key parameters are defined as follows:

[0261] Single-interface unit area application rate in, The amount of adhesive applied to a single interface (g) is the amount of adhesive applied. The area covered by the adhesive (m²) is expressed in g / m².

[0262] Adhesive layer coverage in, The projected area of ​​the glue dots / glue screen. This represents the total area of ​​the interface.

[0263] Increase in pressure drop after humid heat aging in, For the initial pressure drop, For aging Post-pressure drop.

[0264] Peel strength retention in, Initial peel strength, This represents the peel strength after aging.

[0265] 2. Group Design

[0266] Table 1. Sample grouping and structural parameters (n=5, mean ± standard deviation are given in subsequent tables)

[0267]

[0268] Note: E1–E4 cover the key processes in the claims ( , , , ES outer layer); C1–C5 are used to verify the impact of “no outer layer / conventional adhesive / continuous adhesive film / excessive adhesive application / no edge sealing” on the technical effect respectively.

[0269] (II) Testing Methods

[0270] 1. Sample pretreatment and environment

[0271] Sample cutting: Used for resistance / efficiency; Used for peeling.

[0272] Preprocessing: , Leave for 24 hours.

[0273] PUR curing: After lamination, cure under the same conditions for 24 hours (main curing), and 7 days is a reference for full curing.

[0274] 2. Coverage With the amount of adhesive applied Measurement

[0275] 2.1 Application amount

[0276] Take a known area Outer fabric (e.g.) Weigh the mass before coating. With coating quality Therefore, m = - ,according to Calculate the amount of adhesive applied to each interface. Repeat each group three times and take the average.

[0277] 2.2 Coverage

[0278] After coating, the interface image is acquired by scanning / fixed-distance photography, and the projected area of ​​the adhesive dots is calculated after binarization. With the total area of ​​the interface ,according to To obtain coverage, at least 5 fields of view should be counted for each group, and the average value should be taken.

[0279] 3. Initial pressure drop With filtration efficiency

[0280] 1) Equipment and conditions

[0281] Resistance test bench (constant flow fan + differential pressure sensor, range 0–500Pa, accuracy ±1Pa).

[0282] Face wind speed: (Common filter media for evaluating air velocity).

[0283] Aerosol: NaCl, counting particle size 0.3μm channel (or near MPPS channel).

[0284] Effective area of ​​sample: .

[0285] 2) Calculation

[0286] Initial pressure drop: Record (Pa).

[0287] Filtration efficiency: Upstream and downstream particle concentrations are respectively , ,but

[0288] Each group Take the mean ± standard deviation.

[0289] 4. Stability during damp heat aging (resistance drift, adhesion retention)

[0290] 1) Aging conditions

[0291] , They were aged for 24 hours and 7 days, respectively.

[0292] After aging, the samples were quickly sealed and transferred to the test chamber. After 30 minutes of equilibration, the resistance and efficiency were measured.

[0293] 2) Indicators

[0294] , ;

[0295] , Calculate according to the aforementioned formula;

[0296] Efficiency retention rate .

[0297] 5. 180° interlayer peel strength With retention rate

[0298] 1) Specimen width Pre-peeling length ;

[0299] 2) 180° peel, stretching speed ;

[0300] 3) Record the average peel force (N / 25mm);

[0301] 4) Retest after 7 days of humid heat. ,according to Find the retention rate.

[0302] 6. Pleating processing performance

[0303] 1) Conditions (laboratory folding fixture / small origami machine)

[0304] 2) pleat height fold distance pleat length ; 20 items per group.

[0305] 3) Qualification criteria: no through-hole tear, no obvious fiber shedding, continuous folds, and stable sharp corners.

[0306] 4) Indicators:

[0307] 5) Pleating yield

[0308] 6) Radius of the sharp corner Measure the radius of the fold top fillet (mm) under a microscope.

[0309] 7. Effectiveness of edge sealing against water penetration (edge ​​penetration length) )

[0310] 1) Apply drop to the edge of the sample 0.1% methylene blue aqueous solution, let stand for 10 min;

[0311] 2) Cut open the cross-section and measure the maximum inward distance of the staining front. (mm), 5 points are measured in each group and the average value is taken.

[0312] 8. Dust / Clogging Trend

[0313] Using ISOA2 dust or equivalent dust (with stable particle size distribution), under constant airflow, the pressure drop is recorded as a function of the dust mass, and the termination pressure drop is defined. Dust holding capacity per unit area at that time:

[0314] ;

[0315] in, The mass (g) of dust collected when the load is applied to the final pressure drop.

[0316] (III) Experimental Data

[0317] 1. Initial performance (resistance / efficiency / breathability and water repellency)

[0318] Table 2 Initial Performance ( (NaCl 0.3μm channel, n=5)

[0319]

[0320] Summary of technical effects:

[0321] Compared to C3 (PUR continuous film), E1 / E2 / E4 uses a dotted / grid discontinuous adhesive layer, which significantly reduces the initial resistance. (Reducing Pa by approximately 20–35 Pa) demonstrates the effectiveness in preventing continuous film blockage.

[0322] Excessive C4 adhesive application led to Significantly increased, proving The necessity of process control.

[0323] The C2 outer layer's non-liquid-resistant and breathable design (with low hydrostatic pressure resistance) poses a risk of subsequent damp heat / penetration failure.

[0324] 2. Stability during damp heat aging (resistance drift, efficiency retention)

[0325] Table 3 Resistance stability after damp heat aging ( , (n=5)

[0326]

[0327] Summary of technical effects:

[0328] Compared to C1 (glass fiber only), the pressure drop increase after 7 days of humid heat in E1–E4 was […]. The moisture content dropped significantly to about 16%, demonstrating the moisture resistance stability of the outer layer with liquid-resistant and breathable properties and PUR curing bonding.

[0329] Compared to C2 (conventional composite: ordinary nonwoven fabric + EVA continuous film), E1–E4… Significantly lower (approximately) vs This demonstrates that the present invention can effectively suppress the surge in resistance caused by moisture absorption / pore blockage / interface failure of the adhesive layer in high humidity environments.

[0330] Compared to C5 (unsealed), E1 has better edge sealing. The percentage decreased from 41.9% to 16.3%, indicating that the sealing area W has a decisive contribution to blocking the seepage channels at the edge and stabilizing the resistance.

[0331] Compared to C3 (PUR but continuous membrane), E1–E4 significantly reduced initial resistance while maintaining almost the same efficiency and kept low hygrothermal drift, demonstrating the necessity of discontinuous dot / grid coating + coverage control.

[0332] 3. Adhesion reliability (peel strength and retention rate)

[0333] Table 4. Interlayer peel strength (180° peel, n=5)

[0334]

[0335] Summary of technical effects:

[0336] The embodiments of the present invention still maintain their properties after 7 days of humid heat. %, significantly better than C2 ( This demonstrates the moisture resistance reliability of PUR moisture-curing adhesives.

[0337] While C3 has a high retention rate, its continuous film results in excessive resistance. The advantage of this invention—balancing strength and low resistance—comes from its point / mesh structure and... Process.

[0338] 4. Pleating processing performance (yield and sharp corner quality)

[0339] Table 5 Evaluation of pleating processing (20 items per group, n=3 batches)

[0340]

[0341] Summary of technical effects:

[0342] E1–E4 significantly improves the yield of pleated products and forms a smaller sharp corner radius, indicating that the outer waterproof and breathable fabric bears the bending stress and protects the fiberglass layer assembly, thereby improving processing consistency and usable effective area.

[0343] 5. Effectiveness of edge sealing against water penetration (length of edge penetration)

[0344] Table 6. Edge penetration length of dyed water (n=5)

[0345]

[0346] Summary of technical effects:

[0347] Example with edge sealing Unsealed proportions The difference in damp heat resistance drift is highly consistent with that in Table 3, proving that the encapsulated edge region is the key structure for suppressing damp failure channels.

[0348] 6. Dust / Clogging Trend

[0349] Table 7 achieved Dust holding capacity per unit area at time (n=3)

[0350]

[0351] Summary of technical effects:

[0352] The embodiments of the present invention maintain a high dust holding capacity at a low initial resistance, indicating that the dot / mesh bonding and adhesive application process reduces the risk of pore blockage and maintains an effective pore structure.

[0353] From Tables 2–7, it can be concluded that, without sacrificing filtration efficiency, the embodiments of the present invention (E1–E4) exhibit the following characteristics compared to the comparative examples (C1–C5):

[0354] 1) The pressure drop increase is significantly reduced under humid and hot conditions (R_(ΔP,7d)=16%), which is significantly better than glass fiber only (>130) and conventional composite (about 63%); 2) The interlayer adhesion has a high retention rate after humid and hot conditions (K_F=83%), which is significantly better than conventional hot melt adhesive continuous film systems; 3) The pleating process has a high yield and sharper corners (Y=92, r=0.33–0.40, mm), which is significantly better than glass fiber only; 4) The edge sealing and encapsulation significantly reduce the edge water seepage length (L_w≤1, mm), which is consistent with the improvement of humid and hot resistance stability; 5) The dust holding capacity is higher under the same terminal pressure drop conditions, which reflects the preservation of pore structure and the reduction of pore blockage risk.

[0355] VII. Mechanism Explanation and Key Points of Process Control

[0356] 1. Moisture isolation function of the liquid-resistant and breathable outer layer

[0357] The outer ES nonwoven fabric is hydrophobic, and with optional water-repellent finishing, liquid water forms a high contact angle on the surface and is difficult to penetrate; gas can still pass through its pores. This outer layer preferentially absorbs moisture impact and condensation in humid and hot environments, reducing the probability of moisture absorption by the fiberglass layer assembly.

[0358] 2. Interface stabilizing effect of PUR moisture curing

[0359] After PUR coating, it first undergoes hot-melt initial bonding, and then reacts with air moisture to cure and form a cross-linked network. Compared with conventional non-reactive hot melt adhesives, it has stronger resistance to humid heat deformation and creep after curing, and a higher interfacial peel retention rate.

[0360] 3. Dotted / grid discontinuous coating and coverage control

[0361] Discontinuous structures retain a large number of ventilation channels not covered by the membrane, reducing the risk of pore blockage; excessive coverage or continuous membranes will significantly increase initial resistance and weaken dust holding capacity and flux. A stable compromise can be achieved between intensity and flux.

[0362] 4. Application amount The significance of craftsmanship

[0363] Too low a temperature can lead to insufficient interfacial adhesion and interlayer slippage during folding; Excessive heat can cause adhesive dots to spread and pores to become clogged. Examples and comparative cases are provided for verification. It is the preferred process that balances strength and low resistance.

[0364] 5. Encapsulate the edge sealing area The necessity

[0365] In pleated or kerfed filter media, the edges are one of the main weak points for moisture entry. Sealing the edges by directly bonding and encapsulating the fiberglass kerfed edges with two outer layers significantly reduces the length of water seepage at the edges, thereby improving resistance stability after exposure to humid heat. Too small a value will reduce the water-blocking redundancy. Increasing the size can improve moisture resistance stability.

[0366] 6. Protection mechanism during pleating processing

[0367] When folding, the bending stress is mainly borne by the outer layers on both sides, and the fiberglass layer group is near the relatively neutral layer, so the strain is reduced; therefore, fiberglass breakage and fiber loss at the fold are reduced, sharp corners are easier to form, and the yield is improved.

[0368] The above embodiments and comparative examples provide a complete chain of processes and data that can be stably reproduced in the laboratory, from material system to interface bonding, coating morphology, edge sealing and encapsulation to performance verification. This demonstrates that, within the scope of the claims of this invention, composite glass fiber filter materials with low increase in hygrothermal resistance, high adhesion retention rate and good pleating processing performance can be prepared. However, deviations from key limitations (such as no edge sealing, continuous film, excessive adhesive application, excessive outer layer fineness, and excessive number of glass fiber layers) will significantly weaken or eliminate the technical effect of this invention, thus highlighting the necessity and superiority of the technical solution of this invention.

[0369] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A filter material, characterized in that, The filter material is a composite glass fiber filter paper laminated along the thickness direction, which includes a first waterproof and breathable cloth layer, a glass fiber filter paper layer group and a second waterproof and breathable cloth layer in sequence. A first adhesive layer is provided between the first waterproof and breathable fabric layer and the glass fiber filter paper layer group, and a second adhesive layer is provided between the second waterproof and breathable fabric layer and the glass fiber filter paper layer group; Both the first and second adhesive layers are formed from moisture-curing reactive polyurethane hot melt adhesive (PUR); both the first and second adhesive layers have a discontinuous dotted or grid-like coating structure, with an adhesive coverage of 10%–40%; the adhesive application rate per unit area of ​​the first and second adhesive layers is 2.0–2.5 g / m². 2 ; The glass fiber filter paper layer assembly comprises 1–3 layers of glass fiber filter paper; Both the first and second waterproof and breathable fabric layers are formed by ES composite fibers. The ES composite fibers are core-sheath structure fibers with a core component of polypropylene and a sheath component of polyethylene. The fineness of the ES composite fibers is 0.5–30 denier.

2. The filter material according to claim 1, characterized in that, The fineness of the ES composite fiber is 1–20 denier; And / or, the number of layers in the glass fiber filter paper layer assembly is 1–2; And / or, the adhesive layer coverage is 15%–30%; And / or, the equivalent diameter of a single point of the dotted coating structure is 0.2–1.5 mm, and the center distance between adjacent points is 0.5–5 mm.

3. The filter material according to claim 1, characterized in that, At least the outer surface of the first waterproof and breathable fabric layer and the second waterproof and breathable fabric layer has a water-repellent finishing layer or a water-repellent material coating.

4. The filter material according to claim 1, characterized in that, The fiberglass filter paper is wet-processed fiberglass filter paper and contains a thermally self-crosslinking resin adhesive, which is an acrylic or polyurethane adhesive.

5. The filter material according to claim 1, characterized in that, The filter material has a sealing edge area on its circumferential edge, and the width of the sealing edge area is 2–15 mm. Within the sealing edge area, the first waterproof and breathable fabric layer and the second waterproof and breathable fabric layer are bonded to each other by hot pressing and / or continuous PUR bonding to seal the edge of the glass fiber filter paper layer assembly.

6. A filter device, characterized in that, The filter element comprises the filter material according to any one of claims 1–5, and the filter material is folded into a pleated structure to form a filter channel.

7. The filter element according to claim 6, characterized in that, The crease lines of the pleated structure are parallel to the long side of the filter material, and the sealing area is located at the two edges of the pleated structure.

8. A method for preparing the filter material according to any one of claims 1-5, characterized in that, The method includes: Provides a first waterproof and breathable fabric layer, a second waterproof and breathable fabric layer, and a fiberglass filter paper layer assembly including an L-layer of fiberglass filter paper; After melting, the moisture-curing reactive polyurethane hot melt adhesive (PUR) is applied to the first and second composite interfaces in a dotted or grid pattern, ensuring that the adhesive application rate per unit area for each composite interface is 2.0–2.5 g / m². 2 And the adhesive layer coverage meets the requirement of 10%–40%; The first waterproof and breathable fabric layer, the fiberglass filter paper layer, and the second waterproof and breathable fabric layer are bonded and pressurized together to form a first adhesive layer and a second adhesive layer. The circumferential edges of the composite material are sealed by heat pressing and / or continuous PUR sealing, so that the first waterproof and breathable fabric layer and the second waterproof and breathable fabric layer are bonded to each other in the sealing area to seal the edge of the fiberglass filter paper layer group, forming a sealing area with a width of 2–15 mm.

9. The method according to claim 8, characterized in that, After lamination, the PUR undergoes a moisture curing reaction under ambient humidity to form a cross-linked cured structure between the first adhesive layer and the second adhesive layer.

10. The method according to claim 8 or 9, characterized in that, The method further includes: pleating the filter material after forming the sealing edge area to obtain a pleated filter material for origami filters.

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