Gluing-free PET (Polyethylene Terephthalate)-based carbon cloth-sandwiched composite filter material and preparation method thereof

Abstract

The invention discloses an unglued PET (Polyethylene Terephthalate)-based carbon cloth sandwiched composite filter material and a preparation method thereof, and relates to the technical field of air filter materials. The filter material takes PET non-woven fabrics as upper and lower base materials, a chemical filter material is clamped, fiber entanglement and fixation are realized through a glue-free needling process, and a high-performance composite structure is formed through hot rolling and shaping. According to the filter material, use of an adhesive is avoided, waste is common solid waste, and the environmental protection property is excellent; meanwhile, high adsorption efficiency, low airflow resistance, excellent mechanical strength and dimensional stability are kept, and the material is suitable for air purifiers and the like. The preparation process is simple, efficient and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the technical field of composite filter materials, and in particular to a non-adhesive PET-based carbon cloth composite filter material and its preparation method. Background Technology

[0002] Carbon fiber reinforced cloth filter media are widely used in air purifiers, fresh air systems, chemical filters, and FFU (Fan Filter Unit) filter units due to their excellent adsorption performance of chemical pollutants. Currently, most commercially available carbon fiber reinforced cloth filter media are manufactured using an adhesive process, where an adhesive (such as polyurethane or acrylic adhesive) is used to bond and fix the activated carbon or other chemical filter media layer to two layers of supporting non-woven fabric (usually PP or PET). While this adhesive process is technically mature, it has significant drawbacks: the adhesive can clog some of the pores of the chemical filter media, leading to a decrease in adsorption capacity and filtration efficiency, and increasing airflow resistance; some adhesives may release volatile organic compounds (VOCs) during use, causing secondary air pollution; furthermore, used filter media containing adhesives are typically classified as hazardous waste due to the complex organic polymer adhesives, significantly increasing disposal difficulty and cost, which is inconsistent with green manufacturing principles. Therefore, the market urgently needs an adhesive-free, high-performance, and environmentally friendly carbon fiber reinforced cloth filter media manufacturing technology. Summary of the Invention

[0003] This application provides a non-adhesive PET-based carbon cloth composite filter material, characterized in that it comprises at least one upper PET non-woven fabric, at least one lower PET non-woven fabric, and a chemical filter material layer sandwiched between the upper and lower PET non-woven fabrics; the upper and lower PET non-woven fabrics are needle-punched to allow PET fibers to penetrate and entangle the chemical filter material layer, forming a non-adhesive composite structure; the composite structure is further shaped by a hot rolling process to achieve surface smoothness and dimensional stability.

[0004] As a preferred technical solution for a non-adhesive PET-based carbon cloth composite filter material, the chemical filter layer is selected from one or more of granular activated carbon, activated carbon fiber, molecular sieve, and resin particles.

[0005] As a preferred technical solution for a non-adhesive PET-based carbon cloth composite filter material, the upper and lower PET nonwoven fabrics are thermoplastic engineering plastic nonwoven fabrics, preferably PET nonwoven fabrics.

[0006] As a preferred technical solution for a non-adhesive PET-based carbon cloth composite filter material, the composite filter material does not contain adhesives and can be treated as general solid waste after use.

[0007] As a preferred technical solution for a non-adhesive PET-based carbon cloth composite filter material, the composite filter material is used as a chemical filter in an air purifier or fresh air system.

[0008] A preferred technical solution for a non-adhesive PET-based carbon fiber composite filter material includes the following steps: S1, preparing an upper PET non-woven fabric, a lower PET non-woven fabric, and a chemical filter material; S2, uniformly spreading the chemical filter material on the lower PET non-woven fabric, covering the upper PET non-woven fabric, and using a needle-punching process to allow PET fibers to penetrate and entangle the chemical filter material, forming a non-adhesive carbon fiber preform; S3, shaping the carbon fiber preform using a hot rolling process.

[0009] As a preferred technical solution for a non-adhesive PET-based carbon cloth composite filter material, the chemical filter material is selected from one or more of granular activated carbon, activated carbon fiber, molecular sieve, and resin particles.

[0010] As a preferred technical solution for adhesive-free PET-based carbon cloth composite filter material, the needle punching process is a mechanical entanglement process that does not use any adhesives.

[0011] As a preferred technical solution for a non-adhesive PET-based carbon cloth composite filter material, the hot rolling process is carried out under certain temperature and pressure, causing plastic flow on the surface of the PET material to achieve melt bonding and densification.

[0012] As a preferred technical solution for a non-adhesive PET-based carbon cloth composite filter material, the composite filter material obtained by the preparation method has high adsorption efficiency, low airflow resistance and environmental protection characteristics, and is classified as general solid waste after use.

[0013] The adhesive-free PET-based carbon cloth composite filter material and its preparation method provided by this invention have significant beneficial effects. First, it achieves a fundamental breakthrough in environmental protection. By completely eliminating adhesives, it avoids the risk of waste filter material being identified as hazardous waste from the source. After use, it can be treated as general solid waste, significantly reducing disposal costs and environmental burden, which is in line with the concepts of green manufacturing and circular economy. Second, in terms of performance, the adhesive-free needle punching process prevents the adhesive from clogging the pores of the chemical filter material, maximizing the retention of adsorption active sites, thereby improving filtration efficiency and dust holding capacity, and significantly reducing airflow resistance. In addition, the inherent strength and temperature resistance of the PET substrate, combined with the hot rolling and shaping process, makes the filter material structure compact, with a smooth surface, not easily deformed, and has excellent dimensional stability and mechanical durability, which facilitates subsequent processing and installation. Finally, this process adopts a purely physical composite method, which is simple to operate, environmentally friendly and efficient, suitable for large-scale production, and has broad market application prospects. Attached Figure Description

[0014] Figure 1This is a schematic diagram of the structure of the chemical filter material prepared in this application; Detailed Implementation

[0015] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0016] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0017] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0018] Example Example 1: Granular activated carbon composite filter material S1: Prepare materials Choose a weight of 80 g / m 2 The upper and lower layers of PET nonwoven fabric are used, ensuring a fiber diameter of 2-5 dtex and a thickness of 0.5-1 mm. Granular activated carbon is prepared as the chemical filter media, with a particle size of 0.5-2 mm and a specific surface area greater than 1000 m². 2 / g, iodine adsorption value greater than 900 mg / g. The amount of chemical filter media to be used is 200 g / m³. 2 .

[0019] S2: Adhesive-free needle-punched composite Lay the lower layer of PET nonwoven fabric flat on the worktable of the needle punching machine, ensuring a smooth and wrinkle-free surface. Then, evenly spread granular activated carbon onto the lower layer of PET nonwoven fabric, using a vibrating screen or mechanical spreading device to control uniformity and avoid accumulation or gaps. Cover with the upper layer of PET nonwoven fabric, aligning it with the lower layer. Perform lamination via needle punching: set the needle punching density to 1500-2000 needles / cm². 2 The needle-punching depth is 8-12 mm, and the needle-punching speed is 5-10 m / min. During the needle-punching process, PET fibers penetrate the chemical filter media layer from the upper layer and entangle with the lower layer, achieving mechanical fixation and forming a non-adhesive carbon cloth preform. The preform is inspected to ensure that no chemical filter media has fallen off.

[0020] S3: Hot rolling and shaping The needle-punched carbon fiber reinforced preform is fed into a hot rolling mill, with the rolling temperature set at 180-200 ℃, the pressure at 2-4 MPa, and the rolling speed at 2-5 m / min. During hot rolling, plastic flow occurs on the surface of the PET material, achieving fusion bonding of the upper and lower layers and overall densification. After rolling, the filter material thickness is controlled at 1-2 mm, and the surface flatness error is less than 0.1 mm. After cooling to room temperature, it is cut into the required dimensions to obtain the final composite filter material.

[0021] Example 2: Activated carbon fiber composite filter material S1: Prepare materials Choose a weight of 100 g / m 2 The upper and lower layers of PET nonwoven fabric are used, ensuring that their fiber diameter is 3-6 dtex and their thickness is 0.6-1.2 mm. Activated carbon fibers are prepared as the chemical filter media, with a fiber length of 5-10 mm and a specific surface area greater than 1200 m². 2 / g, benzene adsorption rate greater than 30%. The amount of chemical filter media used is 250 g / m³. 2 .

[0022] S2: Adhesive-free needle-punched composite Lay the lower layer of PET nonwoven fabric flat on the worktable of the needle punching machine, ensuring the edges are aligned and without misalignment. Then, evenly spread activated carbon fibers on the lower layer of PET nonwoven fabric, using an air-laid web device or manually to distribute them evenly, ensuring a coverage rate of over 95%. Cover with the upper layer of PET nonwoven fabric and gently press it down. Perform lamination using a needle punching process: set the needle punching density to 1800-2200 needles / cm². 2 The needle-punching depth is 10-14 mm, and the needle-punching speed is 6-12 m / min. During the needle-punching process, the PET fibers penetrate the activated carbon fiber layer and entangle with each other to form a strong, unbonded carbon cloth preform. After lamination, a visual inspection is performed to ensure that no fibers detach.

[0023] S3: Hot rolling and shaping The needle-punched carbon fiber preform is fed into a hot rolling mill, with the rolling temperature set at 190-210 ℃, the pressure at 3-5 MPa, and the rolling speed at 3-6 m / min. During hot rolling, the surface of the PET fibers is melted, achieving interlayer bonding and structural densification. After rolling, the filter material thickness is controlled at 1.2-2.2 mm, with a smooth, burr-free surface. After natural cooling, it is wound or cut into sheets to obtain the final composite filter material.

[0024] Example 3: Molecular sieve composite filter material S1: Prepare materials Choose a weight of 90 g / m 2The upper and lower layers of PET nonwoven fabric are used, ensuring a fiber diameter of 2.5-5.5 dtex and a thickness of 0.55-1.1 mm. Molecular sieves are prepared as the chemical filter media; these are of type 4A or 13X, with a particle size of 1-3 mm and an adsorption capacity greater than 20% (water vapor). The amount of chemical filter media used is 220 g / m³. 2 .

[0025] S2: Adhesive-free needle-punched composite Lay the lower layer of PET nonwoven fabric flat on the worktable of the needle punching machine, ensuring uniform tension and no slack. Then, evenly spread the molecular sieves onto the lower layer of PET nonwoven fabric, using a roller spreader to control the particle distribution and avoid local aggregation. Cover with the upper layer of PET nonwoven fabric, aligning the edges. Perform lamination using a needle punching process: set the needle punching density to 1600-2100 needles / cm². 2 The needle-punching depth is 9-13 mm, and the needle-punching speed is 5.5-11 m / min. During the needle-punching process, PET fibers mechanically penetrate and fix the molecular sieve particles, forming a non-adhesive carbon cloth preform. After lamination, a shaking test ensures that the particles do not shift.

[0026] S3: Hot rolling and shaping The needle-punched carbon fiber reinforced preform is fed into a hot rolling mill, with the hot rolling temperature set at 185-205 ℃, the pressure at 2.5-4.5 MPa, and the rolling speed at 2.5-5.5 m / min. During the hot rolling process, the PET material undergoes plastic deformation, achieving fusion bonding and uniform thickness. After rolling, the filter material thickness is controlled at 1.1-2.1 mm, with a dimensional stability error of less than 0.05 mm. After cooling and setting, the surface flatness is inspected to obtain the final composite filter material.

[0027] Example 4: Resin Particle Composite Filter Material S1: Prepare materials Choose a weight of 85 g / m 2 The upper and lower layers of PET nonwoven fabric are used, ensuring a fiber diameter of 2-4 dtex and a thickness of 0.5-1 mm. Resin granules are prepared as the chemical filter media; these are ion exchange resins with a particle size of 0.3-1.2 mm and an exchange capacity greater than 1 meq / mL. The amount of chemical filter media used is 210 g / m³. 2 .

[0028] S2: Adhesive-free needle-punched composite Lay the lower layer of PET nonwoven fabric flat on the worktable of the needle punching machine, ensuring a dust-free environment to avoid contamination. Then, evenly spread the resin granules onto the lower layer of PET nonwoven fabric, using a vibrating distributor to ensure a consistent granule layer thickness. Cover with the upper layer of PET nonwoven fabric and secure it in place. Perform lamination using a needle punching process: set the needle punching density to 1700-2000 needles / cm². 2 The needle-punching depth was 8.5-12.5 mm, and the needle-punching speed was 5-10.5 m / min. During the needle-punching process, PET fiber filaments entangled and fixed resin particles, forming an unbonded carbon fiber preform. After lamination, a weight uniformity test was performed.

[0029] S3: Hot rolling and shaping The needle-punched carbon fiber reinforced preform is fed into a hot rolling mill, with the hot rolling temperature set at 182-202 ℃, the pressure at 2.2-4.2 MPa, and the rolling speed at 2.2-5.2 m / min. During hot rolling, the flow and bonding of the PET surface are promoted, achieving structural strengthening and densification. After rolling, the filter material thickness is controlled at 1-2 mm, with a smooth surface. After forced air cooling, the edges are cut to obtain the final composite filter material.

[0030] Example 5: Composite filter material of granular activated carbon and molecular sieve S1: Prepare materials Choose a weight of 95 g / m 2 The upper and lower layers of PET nonwoven fabric are prepared, ensuring a fiber diameter of 3-5 dtex and a thickness of 0.6-1.1 mm. A mixture of granular activated carbon and molecular sieves is prepared as the chemical filter media, with granular activated carbon comprising 60% (particle size 0.5-2 mm, specific surface area >1000 m²). 2 / g), molecular sieve content 40% (particle size 1-3 mm). The total chemical filter media dosage is 230 g / m³. 2 And premix evenly.

[0031] S2: Adhesive-free needle-punched composite Lay the lower layer of PET nonwoven fabric flat on the worktable of the needle punching machine, ensuring high flatness. Then, evenly spread the premixed granular activated carbon and molecular sieves onto the lower layer of PET nonwoven fabric, using a mixing and spreading device to control the proportion and distribution. Cover with the upper layer of PET nonwoven fabric and flatten. Perform lamination through a needle punching process: set the needle punching density to 1650-2150 needles / cm². 2 The needle-punching depth is 9.5-13.5 mm, and the needle-punching speed is 5.8-11.5 m / min. During the needle-punching process, PET fibers penetrate and entangle in the mixed filter material layer, forming a non-adhesive carbon cloth preform. After lamination, sampling is performed to check the uniformity of mixing.

[0032] S3: Hot rolling and shaping The needle-punched carbon fiber reinforced preform is fed into a hot rolling mill, with the hot rolling temperature set at 188-208 ℃, the pressure at 2.8-4.8 MPa, and the rolling speed at 2.8-5.8 m / min. During the hot rolling process, the PET is melt-bonded and the overall material is compressed and densified. After rolling, the filter material thickness is controlled at 1.15-2.15 mm, and the strength is increased by more than 20%. After water cooling, it is wound and stored to obtain the final composite filter material.

[0033] Comparison Example Comparison with Example 1: Adhesive bonding (for inventions without adhesive bonding) S1: Prepare materials Choose a weight of 80 g / m 2 The upper and lower layers of PET nonwoven fabric are used, ensuring a fiber diameter of 2-5 dtex and a thickness of 0.5-1 mm. Granular activated carbon is prepared as the chemical filter media, with a particle size of 0.5-2 mm and a specific surface area greater than 1000 m². 2 / g, iodine adsorption value greater than 900 mg / g. The amount of chemical filter media to be used is 200 g / m³. 2 Prepare additional polyurethane adhesive as a binder.

[0034] S2: Adhesive bonding Lay the lower layer of PET nonwoven fabric flat on the laminating machine's worktable, ensuring a smooth, wrinkle-free surface. Then, evenly spread granular activated carbon onto the lower layer of PET nonwoven fabric, using a vibrating screen or mechanical spreading device to control uniformity and avoid accumulation or gaps. Evenly coat the surface of the chemical filter layer with polyurethane adhesive at a coating amount of 50 g / m². 2 Cover with an upper layer of PET nonwoven fabric, aligning it with the lower layer. Perform lamination using a pressure roller process: pressure of 1-2 MPa and speed of 5-10 m / min, achieving adhesive bonding and forming an adhesive-coated carbon fiber preform. Inspect the preform to ensure no chemical filter material has detached, but note that adhesive may partially clog the pores.

[0035] S3: Hot rolling and shaping The composite carbon fiber preform was fed into a hot rolling mill, with the rolling temperature set at 180-200 ℃, the pressure at 2-4 MPa, and the rolling speed at 2-5 m / min. During hot rolling, the PET material surface underwent plastic flow, but the adhesive may have affected overall densification. After rolling, the filter material thickness was controlled at 1-2 mm, and the surface flatness error was less than 0.1 mm. After cooling to room temperature, it was cut into the required size to obtain the final composite filter material. Compared with Example 1, this comparative example only used an adhesive instead of the needle punching process in step S2, which may have led to secondary pollution of the filter material, a decrease in adsorption efficiency, and its classification as hazardous waste.

[0036] Comparison with Example 2: Needle-punched composite without hot rolling (for the invention point of hot rolling finalization) S1: Prepare materials Choose a weight of 80 g / m 2 The upper and lower layers of PET nonwoven fabric are used, ensuring a fiber diameter of 2-5 dtex and a thickness of 0.5-1 mm. Granular activated carbon is prepared as the chemical filter media, with a particle size of 0.5-2 mm and a specific surface area greater than 1000 m². 2 / g, iodine adsorption value greater than 900 mg / g. The amount of chemical filter media to be used is 200 g / m³. 2 .

[0037] S2: Adhesive-free needle-punched composite Lay the lower layer of PET nonwoven fabric flat on the worktable of the needle punching machine, ensuring a smooth and wrinkle-free surface. Then, evenly spread granular activated carbon onto the lower layer of PET nonwoven fabric, using a vibrating screen or mechanical spreading device to control uniformity and avoid accumulation or gaps. Cover with the upper layer of PET nonwoven fabric, aligning it with the lower layer. Perform lamination via needle punching: set the needle punching density to 1500-2000 needles / cm². 2 The needle-punching depth is 8-12 mm, and the needle-punching speed is 5-10 m / min. During the needle-punching process, PET fibers penetrate the chemical filter media layer from the upper layer and entangle with the lower layer, achieving mechanical fixation and forming a non-adhesive carbon cloth preform. The preform is inspected to ensure that no chemical filter media has fallen off.

[0038] S3: Natural cooling and shaping (without hot rolling) The needle-punched carbon fiber preform was allowed to cool and set naturally at room temperature, without the need for hot rolling. During cooling, the structure was maintained solely by the mechanical entanglement formed after needle punching, with the thickness controlled at 1.5-2.5 mm, and slight surface unevenness was possible. After cooling to room temperature, it was cut to the required size to obtain the final composite filter material. Compared to Example 1, this comparative example omitted only the hot rolling process in step S3, resulting in a looser filter material structure, poorer dimensional stability, and susceptibility to deformation, which is detrimental to processing and installation.

[0039] Comparison with Example 3: Using PP nonwoven fabric instead of PET (the invention point of PET material) S1: Prepare materials Choose a weight of 80 g / m 2 The upper and lower layers of PP nonwoven fabric are used, ensuring a fiber diameter of 2-5 dtex and a thickness of 0.5-1 mm. Granular activated carbon is prepared as the chemical filter media, with a particle size of 0.5-2 mm and a specific surface area greater than 1000 m². 2 / g, iodine adsorption value greater than 900 mg / g. The amount of chemical filter media to be used is 200 g / m³.2 .

[0040] S2: Adhesive-free needle-punched composite Lay the lower layer of PP nonwoven fabric flat on the worktable of the needle punching machine, ensuring a smooth and wrinkle-free surface. Then, evenly spread granular activated carbon onto the lower layer of PP nonwoven fabric, using a vibrating screen or mechanical spreading device to control uniformity and avoid accumulation or gaps. Cover with the upper layer of PP nonwoven fabric, aligning it with the lower layer. Perform lamination using a needle punching process: set the needle punching density to 1500-2000 needles / cm². 2 The needling depth is 8-12 mm, and the needling speed is 5-10 m / min. During the needling process, PP fibers penetrate the chemical filter media layer from the upper layer and entangle into the lower layer, achieving mechanical fixation and forming a non-adhesive carbon cloth preform. The preform is inspected to ensure that no chemical filter media has fallen off.

[0041] S3: Hot rolling and shaping The needle-punched carbon fiber reinforced preform was fed into a hot rolling mill, with the hot rolling temperature set at 140-160 ℃ (adapted to the melting point of PP), the pressure at 2-4 MPa, and the rolling speed at 2-5 m / min. During the hot rolling process, plastic flow occurred on the surface of the PP material, achieving fusion bonding and overall densification of the upper and lower layers. After rolling, the filter material thickness was controlled at 1-2 mm, and the surface flatness error was less than 0.1 mm. After cooling to room temperature, it was cut into the required size to obtain the final composite filter material. Compared with Example 1, this comparative example only changed the upper and lower layer materials from PET to PP, resulting in lower temperature resistance and mechanical strength of the filter material, inferior hot rolling effect compared to PET, and insufficient overall stability.

[0042] Table 1

[0043] As can be seen from the experimental data table, the adhesive-free PET-based carbon cloth composite filter material of the present invention exhibits significant performance advantages in Examples 1 to 4, specifically in terms of adsorption efficiency, airflow resistance, tensile strength, dimensional stability, and waste classification. Taking granular activated carbon as an example, the adsorption efficiency of Example 1 is as high as 95%, far exceeding that of Control Example 1 (with adhesive process) at 85%, Control Example 2 (needle punching only, no hot rolling) at 90%, and Control Example 3 (PP substrate) at 88%. This is due to the fact that the adhesive-free needle punching process avoids the clogging of the chemical filter material pores by the adhesive, thereby maximizing the retention of active sites and increasing the filtration capacity. At the same time, the airflow resistance is only 25 Pa, significantly lower than that of Control Example 1 at 40 Pa, Control Example 2 at 30 Pa, and Control Example 3 at 35 Pa, indicating that the purely physical composite method reduces the risk of increased resistance and optimizes airflow. Regarding tensile strength, Examples 1-4 consistently maintained a strength between 145-160 N / 5cm, superior to Control Example 1's 140 N / 5cm, Control Example 2's 120 N / 5cm (due to the lack of hot rolling and resulting in a loose structure), and Control Example 3's 130 N / 5cm (due to the lower strength of PP material). This demonstrates that the hot rolling process achieves interlayer melt bonding and overall densification through the plastic flow of PET material, improving mechanical durability. Dimensional stability (deformation rate) was controlled at 1.0-1.5% in the examples, significantly lower than Control Example 1's 2.0%, Control Example 2's 3.5% (easily deformed without hot rolling), and Control Example 3's 2.8% (due to the poor temperature resistance of PP), highlighting the thermal stability and deformation resistance of the PET substrate combined with hot rolling. Furthermore, all examples were classified as general solid waste, while Control Example 1 was classified as hazardous waste due to its adhesive content. This addresses environmental compliance issues at the source and reduces disposal costs. Overall, Examples 2 (activated carbon fiber), 3 (molecular sieve), and 4 (resin particles) also showed similar trends, with adsorption efficiencies of 92-96%, resistance of 22-28 Pa, strength of 145-160 N / 5cm, and deformation rate of 1.0-1.5%, all of which were superior to the control group. This verified the synergistic effect of the "glue-free needle punching + hot rolling shaping" process and PET materials, achieving a comprehensive innovation that surpasses traditional methods in terms of performance improvement, structural optimization, and green environmental protection.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A non-adhesive PET-based carbon cloth-insulated composite filter material, characterized in that, It includes at least one upper PET nonwoven fabric, at least one lower PET nonwoven fabric, and a chemical filter material layer sandwiched between the upper and lower PET nonwoven fabrics; the upper and lower PET nonwoven fabrics are needle-punched to allow PET fibers to penetrate and entangle the chemical filter material layer, forming a non-adhesive composite structure; the composite structure is further shaped by a hot rolling process.

2. The adhesive-free PET-based carbon cloth composite filter material according to claim 1, characterized in that, The chemical filter media layer is selected from one or more of granular activated carbon, activated carbon fiber, molecular sieve, and resin particles.

3. The non-adhesive PET-based carbon cloth composite filter material according to claim 1, characterized in that, The upper and lower PET nonwoven fabrics are thermoplastic engineering plastic nonwoven fabrics, preferably PET nonwoven fabrics.

4. The non-adhesive PET-based carbon cloth composite filter material according to claim 1, characterized in that, The composite filter material does not contain adhesives.

5. The non-adhesive PET-based carbon cloth composite filter material according to claim 1, characterized in that, The composite filter material is used as a chemical filter in air purifiers or fresh air systems.

6. A method for preparing an adhesive-free PET-based carbon cloth-insulated composite filter material, characterized in that, Includes the following steps: S1. Prepare an upper layer of PET nonwoven fabric, a lower layer of PET nonwoven fabric, and chemical filter material; S2. Spread the chemical filter material evenly on the lower layer of PET nonwoven fabric, cover the upper layer of PET nonwoven fabric, and use a needle punching process to allow PET fibers to penetrate and entangle the chemical filter material to form a non-adhesive carbon fiber preform; S3. Shape the carbon fiber preform using a hot rolling process.

7. The preparation method according to claim 6, characterized in that, The chemical filter material is selected from one or more of granular activated carbon, activated carbon fiber, molecular sieve, and resin particles.

8. The preparation method according to claim 6, characterized in that, The needle-punching process is a mechanical entanglement process.

9. The preparation method according to claim 6, characterized in that, The hot rolling process is carried out under certain temperature and pressure conditions, causing plastic flow on the surface of the PET material.

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