A method for making stiff filter material without glue for filter cartridges

Abstract

The application relates to the technical field of filtering materials, and particularly discloses a stiffening filter material glue-free preparation method for a filter cartridge. The preparation method comprises the following steps: opening, blending, carding, laying, and needling fiber raw materials to form a filter material layer, wherein the fiber raw materials comprise ES fibers or at least two fibers with different melting points; performing water jet reinforcement on the filter material layer to obtain felt material; heating the felt material, when the fiber raw materials comprise ES fibers, heating the felt material to 130-150 DEG C; when the fiber raw materials comprise at least two fibers with different melting points, heating the felt material to a temperature between the melting point temperatures of the two fibers with different melting points; heat rolling for 30-60 s, cooling to room temperature, and obtaining stiffening filter material for the filter cartridge. The preparation method avoids the problem of uneven absorption of stiffening agent by the filter material caused by the use of the stiffening agent, helps the filter material to maintain high stiffness and breaking strength, and improves the environmental protection and simplicity of the preparation method.

Description

Technical Field

[0001] This invention relates to the technical field of filter materials, and in particular to a method for preparing rigid filter media for filter cartridges without adhesive. Background Technology

[0002] In the fields of environmental protection and industrial filtration, filter cartridges, as a highly efficient filtration device, are widely used in the filtration of various gases. The performance of a filter cartridge largely depends on the properties of its filter media. Traditional filter media often suffer from problems such as softness and easy deformation, which to some extent affects the filtration performance and effectiveness of the filter cartridge. Stiffening treatment is a method to enhance the rigidity and stability of the filter media fibers, thereby improving the filtration effect and service life of the filter cartridge.

[0003] In related technologies, a method for hardening and finishing filter cartridge substrates is disclosed, wherein the high temperature refers to the operating temperature of the substrate filter material being 130℃-280℃; the specific steps are as follows: Step 1, mixing methyl silicone resin, hydrogen-containing silicone oil emulsion, and water in a mass fraction of 10%-30%: 15%-45%: 25%-75% and stirring evenly to prepare a high-temperature resistant hardening agent; Step 2, immersing the filter cartridge substrate in the above-mentioned high-temperature resistant hardening agent and rolling it dry with rollers, controlling the roll residue rate to be 110-130%; Step 3, placing the rolled-dry filter cartridge substrate in an oven at 210±2℃ for 10-15 minutes for cross-linking and curing.

[0004] The aforementioned method for stiffening filter media uses stiffening agents made from chemical reagents such as methyl silicone resin and hydrogen-containing silicone oil emulsion. The stiffness of the filter media is enhanced through steps such as impregnation, rolling, and cross-linking curing. This process not only increases the operational difficulty but also raises concerns about environmental friendliness due to the large amount of stiffening agent used. Furthermore, uneven absorption of the stiffening agent by the filter media during impregnation and rolling can lead to a decrease in the stiffness and tensile strength of the filter media. Summary of the Invention

[0005] In order to improve the stiffness and tensile strength of filter media, enhance the environmental friendliness of the preparation method, and reduce the operational difficulty of the preparation method, this application provides a glue-free preparation method for stiff filter media for filter cartridges.

[0006] This application provides a method for preparing rigid filter media for filter cartridges without adhesive, which adopts the following technical solution:

[0007] A method for preparing rigid filter media for filter cartridges without adhesive, comprising the following steps:

[0008] Filter media layer preparation: The fiber raw material is opened, blended, carded, laid into a web and needle punched to form a filter media layer. The fiber raw material includes ES fiber or at least two kinds of fibers with different melting points.

[0009] Reinforcement: The filter media layer is reinforced with hydroentangling to obtain felt material;

[0010] Stiffening process: Heat the felt material to 130-150°C when the fiber raw material includes ES fiber; heat the felt material to between the melting point temperatures of the two fibers when the fiber raw material includes at least two fibers with different melting points; hold the heat for 30-60 seconds and cool to room temperature to obtain stiff filter material for filter cartridges.

[0011] By employing the above technical solution, ES fiber or at least two fibers with different melting points are selected. ES fiber is a composite fiber made of polypropylene and polyethylene. When heated, some components of the ES fiber soften and melt. When heated to a temperature between their melting points, the lower-melting-point fiber melts first, while the higher-melting-point fiber remains solid. During heating, these partially molten components form bonding points, binding the fibers together in the filter media layer. This bonding effect not only enhances the structural stability of the filter media but also gives it a macroscopically rigid characteristic. Simultaneously, the heat-insulating hot rolling step further promotes the bonding and fusion between fibers, making the filter media even more rigid. During hot rolling, the partially molten components flow and fill the gaps between fibers, forming a denser structure. After cooling to room temperature, the bonding points in the filter media solidify, resulting in a filter media with rigid properties. This structure not only improves the stiffness and tensile strength of the filter media but also enhances its dust removal efficiency. Therefore, the preparation method of this application avoids the problem of uneven absorption of stiffening agents by the filter media that may be caused by the use of stiffening agents, which helps the filter media maintain high stiffness and tensile strength. It also improves the environmental friendliness of the preparation method. The preparation process does not require steps such as impregnation, rolling, cross-linking and curing, making it simpler.

[0012] In one specific implementation, the fiber raw material includes A fiber and PP fiber, wherein the A fiber is any one of polyester fiber, PPS fiber, aramid fiber, and PI fiber; in the stiffening step, the felt material is heated to 90-110°C.

[0013] By adopting the above technical solutions, polyester fiber, PPS fiber, aramid fiber, and PI fiber each possess unique properties, such as strength, temperature resistance, and chemical corrosion resistance. This allows the filter media to be customized according to the specific application requirements. During the heating process at 85-110℃, PP fiber softens and melts, forming stable bonding points. These bonding points not only optimize the pore structure and distribution of the filter media and enhance its structural stability, but also help maintain the stiffness and tensile strength of the filter media.

[0014] In one specific implementation, the weight ratio of A fiber to PP fiber in the fiber raw material is 1:(0.4-0.8).

[0015] By adopting the above technical solution, this application has found that using the two fibers in the above proportions can further improve the dust removal efficiency of the filter media. This may be because, under the above proportions, the resulting filter media structure has better dust removal performance.

[0016] In one specific implementation, the PP fiber is prepared according to the following steps:

[0017] After cleaning and drying the PP masterbatch, it is mixed with glycidyl methacrylate and benzoyl peroxide, heated to 150-180℃, and melt-blended to obtain the melt material.

[0018] The molten material is electrospun to obtain PP fibers.

[0019] By employing the above technical solution, after the PP masterbatch is mixed and melted with glycidyl methacrylate and benzoyl peroxide, glycidyl methacrylate can be grafted onto the PP molecular chain under the initiation of benzoyl peroxide. This introduces polar groups into the PP molecular chain, improving the adhesion between PP fibers and other fibers, and enhancing the strength of the PP fibers. This helps the PP fibers form a more stable bond with other fibers after melting and solidification, further enhancing the stiffness and tensile strength of the filter media.

[0020] In one specific implementation, the weight ratio of the PP masterbatch, glycidyl methacrylate, and benzoyl peroxide is 100:(5-15):(0.1-0.25).

[0021] By adopting the above technical solution, this application found through experiments that the PP fibers obtained using the above raw material ratios all have high strength, and the filter media prepared with these PP fibers have high stiffness and tensile strength. This may be because, within the above ratio range, the melt blending process is more stable, reducing the problems of viscosity unevenness and decreased thermal stability caused by improper component ratios, resulting in higher strength and adhesion of the PP fibers.

[0022] In one specific implementation, the PP masterbatch comprises the following raw materials in parts by weight: 80-100 parts of PP resin, 10-20 parts of ethoxylated alkylamine, 3-8 parts of plasticizer, and 2-5 parts of stabilizer.

[0023] By employing the above technical solutions, ethoxylated alkylamines, with their excellent electrical conductivity, can enhance the antistatic properties of PP masterbatch, thereby improving the antistatic performance of the filter media. Plasticizers can lower the melting temperature of PP masterbatch, improve its flowability and processing properties, and facilitate a smoother melt blending process. Stabilizers can improve the mechanical and processing properties of PP masterbatch. Therefore, PP masterbatch using the above raw material ratios can produce PP fibers with better antistatic properties and flexibility, further improving the tensile strength and safety of the filter media.

[0024] In one specific implementation, the plasticizer is diisononyl phthalate.

[0025] By adopting the above technical solution, diisononyl phthalate can effectively reduce the glass transition temperature of PP resin, making it softer and easier to process. Furthermore, diisononyl phthalate has good compatibility with PP resin and can be uniformly dispersed in the resin.

[0026] In one specific implementation, the stabilizer comprises zinc stearate and hindered amine in a weight ratio of 1:(0.6-1.2).

[0027] By adopting the above technical solution, zinc stearate and hindered amine exhibit good compatibility in PP resin, forming a uniform dispersion system. Zinc stearate can reduce the melt viscosity of PP resin, improve its flowability, and make the melt blending process smoother. Simultaneously, hindered amine helps reduce the thermal degradation of PP resin during processing. Experiments in this application have shown that PP fibers prepared using PP resin with zinc stearate and hindered amine within the above weight ratio range can further improve the tensile strength of the filter media. This may be because the above raw material ratio can improve the flexibility of the PP fibers.

[0028] In one specific feasible embodiment, the PP masterbatch is prepared according to the following steps:

[0029] PP resin, ethoxylated alkylamine, plasticizer and stabilizer are mixed evenly to obtain a mixture;

[0030] The mixture is melt-blended to obtain a melt;

[0031] The melt is extruded and granulated to obtain PP masterbatch.

[0032] By adopting the above technical solution, the PP resin, ethoxylated amine antistatic agent, plasticizer and stabilizer are first uniformly mixed, which helps the various additives to be uniformly dispersed in the PP resin.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. The preparation method of this application avoids the problem of uneven absorption of stiffening agent by the filter media that may be caused by the use of stiffening agent, which helps the filter media maintain high stiffness and tensile strength. It also improves the environmental friendliness of the preparation method. The preparation process does not require impregnation, rolling, cross-linking and curing steps, making it simpler.

[0035] 2. In this application, it is preferred to use any one of polyester fiber, PPS fiber, aramid fiber, PI fiber and PP fiber as fiber raw materials, which helps to further improve the stiffness and tensile strength of the filter material.

[0036] 3. This application preferably uses PP masterbatch with a specific raw material ratio, which can further improve the tensile strength and safety of the filter media. Detailed Implementation

[0037] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0038] Example

[0039] Example 1

[0040] This embodiment provides a method for preparing rigid filter media for filter cartridges without adhesive, including the following steps:

[0041] ES fibers (Jinyou, 2D*38mm) are opened, blended, carded, web-laid, and needle-punched, with a needle-punching density of 80 needles / cm. 2 The needle penetration depth is 13mm, forming a filter media layer;

[0042] The filter media layer was reinforced by hydroentangling with 5 hydroentangling heads, a hydroentangling pressure of 310 bar, and a machine speed of 5.5 m / min to obtain the felt material.

[0043] The felt material is heated to 140°C and then kept at 140°C for hot rolling for 45 seconds. It is then naturally cooled to room temperature to obtain a stiff filter material for filter cartridges.

[0044] Example 2

[0045] The only difference between this embodiment and Embodiment 1 is that the felt material is heated to 130°C and then kept at 130°C for hot rolling for 60 seconds, and then naturally cooled to room temperature to obtain a stiff filter material for filter cartridges.

[0046] Example 3

[0047] The only difference between this embodiment and Embodiment 1 is that the felt material is heated to 150°C and then kept at 130°C for hot rolling for 30 seconds, and then naturally cooled to room temperature to obtain a stiff filter material for filter cartridges.

[0048] Example 4

[0049] This embodiment provides a method for preparing rigid filter media for filter cartridges without adhesive, including the following steps:

[0050] The fiber raw materials are opened, blended, carded, web-laid, and needle-punched, with a needle-punching density of 80 needles / cm². 2 The needle-punching depth is 13mm to form a filter layer. The fiber raw materials include polyester fiber (Longfeng Chemical Fiber, 1.5D*32mm) and PP fiber (Tonghui, diameter 25um, length 15mm) in a weight ratio of 10:6.

[0051] The filter media layer was reinforced by hydroentangling with 5 hydroentangling heads, a hydroentangling pressure of 310 bar, and a machine speed of 5.5 m / min to obtain the felt material.

[0052] The felt material is heated to 100°C and then kept at 100°C for hot rolling for 45 seconds. It is then naturally cooled to room temperature to obtain a stiff filter material for filter cartridges.

[0053] Example 5

[0054] The only difference between this embodiment and embodiment 4 is that the fiber raw materials include polyester fiber (Longfeng Chemical Fiber, 1.5D*32mm) and PP fiber (Tonghui, diameter 25um, length 15mm) in a weight ratio of 10:2.

[0055] Example 6

[0056] The only difference between this embodiment and embodiment 4 is that the fiber raw materials include polyester fiber (Longfeng Chemical Fiber, 1.5D*32mm) and PP fiber (Tonghui, diameter 25um, length 15mm) in a weight ratio of 10:4.

[0057] Example 7

[0058] The only difference between this embodiment and embodiment 4 is that the fiber raw materials include polyester fiber (Longfeng Chemical Fiber, 1.5D*32mm) and PP fiber (Tonghui, diameter 25um, length 15mm) in a weight ratio of 10:8.

[0059] Example 8

[0060] The only difference between this embodiment and embodiment 4 is that the fiber raw materials include polyester fiber (Longfeng Chemical Fiber, 1.5D*32mm) and PP fiber (Tonghui, diameter 25um, length 15mm) in a weight ratio of 1:1.

[0061] Example 9

[0062] The only difference between this embodiment and embodiment 4 is that the fiber raw materials include PPS fiber (Huiweishi, 1.5D*32mm) and PP fiber (Tonghui, diameter 25um, length 15mm) in a weight ratio of 10:6.

[0063] Example 10

[0064] The only difference between this embodiment and embodiment 4 is that the fiber raw materials include aramid fiber (Putek, 1.5D*32mm) and PP fiber (Tonghui, diameter 25um, length 15mm) in a weight ratio of 10:6.

[0065] Example 11

[0066] The only difference between this embodiment and embodiment 4 is that the fiber raw materials include PI fiber (Wenqi, 1.5D*32mm) and PP fiber (Tonghui, diameter 25um, length 15mm) in a weight ratio of 10:6.

[0067] Example 12

[0068] The only difference between this embodiment and embodiment 4 is that the felt material is heated to 90°C and then kept at 90°C for hot rolling for 60 seconds, and then naturally cooled to room temperature to obtain a stiff filter material for filter cartridges.

[0069] Example 13

[0070] The only difference between this embodiment and embodiment 4 is that the felt material is heated to 110°C and then kept at 110°C for hot rolling for 30 seconds, and then naturally cooled to room temperature to obtain a stiff filter material for filter cartridges.

[0071] Example 14

[0072] The only difference between this embodiment and Example 4 is that the PP fiber in this embodiment is prepared according to the following steps:

[0073] First, PP masterbatch is prepared. The PP masterbatch consists of the following raw materials: 90 kg of PP resin, 15 kg of ethoxylated alkylamine, 5 kg of diisononyl phthalate, and 4 kg of zinc stearate.

[0074] PP resin, ethoxylated alkylamine, diisononyl phthalate and zinc stearate were mixed evenly to obtain a mixture.

[0075] The mixture is heated to 175°C and melt-blended to obtain a melt.

[0076] The melt is extruded and granulated to obtain PP masterbatch.

[0077] Then, PP fibers are prepared. After washing the PP masterbatch with water and drying it, it is mixed with PP masterbatch, glycidyl methacrylate and benzoyl peroxide in a weight ratio of 100:10:0.2, heated to 165°C, and melt-blended to obtain a melt material.

[0078] The molten material was electrospun to obtain PP fibers (25 μm in diameter and 15 mm in length).

[0079] Example 15

[0080] The only difference between this embodiment and Embodiment 14 is that, in the preparation process of the PP masterbatch, the PP masterbatch includes the following raw materials: 80 kg of PP resin, 20 kg of ethoxylated alkylamine, 8 kg of diisononyl phthalate, and 5 kg of zinc stearate.

[0081] Example 16

[0082] The only difference between this embodiment and Embodiment 14 is that, in the preparation process of the PP masterbatch, the PP masterbatch includes the following raw materials: 100 kg of PP resin, 10 kg of ethoxylated alkylamine, 3 kg of diisononyl phthalate, and 2 kg of zinc stearate.

[0083] Example 17

[0084] The only difference between this embodiment and Example 14 is that, in the process of preparing the PP masterbatch, zinc stearate is replaced with a mixture of zinc stearate and hindered amine (BASF 944) in equal weight ratios of 1:1.

[0085] Example 18

[0086] The only difference between this embodiment and Embodiment 14 is that, in the process of preparing PP fibers, the PP masterbatch is washed with water, dried, and then mixed with PP masterbatch, glycidyl methacrylate and benzoyl peroxide in a weight ratio of 100:5:0.25. The mixture is then heated to 165°C and melt-blended to obtain a molten material.

[0087] Example 19

[0088] The only difference between this embodiment and Example 14 is that, in the process of preparing PP fibers, the PP masterbatch is washed with water, dried, and then mixed with PP masterbatch, glycidyl methacrylate and benzoyl peroxide in a weight ratio of 100:15:0.1. The mixture is then heated to 165°C and melt-blended to obtain a melt material.

[0089] Example 20

[0090] The only difference between this embodiment and Example 14 is that, in the process of preparing PP fibers, PP masterbatch, glycidyl methacrylate and benzoyl peroxide are mixed in a weight ratio of 100:10:0.2, heated to 150°C, and melt-blended to obtain a molten material.

[0091] Example 21

[0092] The only difference between this embodiment and Embodiment 14 is that, in the process of preparing PP fibers, PP masterbatch, glycidyl methacrylate and benzoyl peroxide are mixed in a weight ratio of 100:10:0.2, heated to 180°C, and melt-blended to obtain a molten material.

[0093] Comparative Example

[0094] Comparative Example 1

[0095] The only difference between this comparative example and Example 1 is that an equal amount of polypropylene fiber (2D*38mm) was used to replace the ES fiber (Jinyou, 2D*38mm).

[0096] Comparative Example 2

[0097] The only difference between this comparative example and Example 1 is that an equal amount of polyethylene fiber (2D*38mm) was used to replace the ES fiber (Jinyou, 2D*38mm).

[0098] Comparative Example 3

[0099] The only difference between this comparative example and Example 4 is that the fiber raw material includes only polyester fiber (Longfeng Chemical Fiber, 1.5D*32mm).

[0100] Comparative Example 4

[0101] The only difference between this comparative example and Example 4 is that the fiber raw material includes only PP fiber (Tonghui, diameter 25um, length 15mm).

[0102] Performance testing

[0103] The following performance tests were conducted on the rigid filter media for filter cartridges prepared in Examples 1-21 and Comparative Examples 1-4:

[0104] The stiffness (mN) of the stiff filter media used in filter cartridges at 25°C was measured using a stiffness tester.

[0105] According to GB / T12625-1990, the dust removal efficiency of rigid filter media used in filter cartridges shall be tested.

[0106] According to GB / T 3923.1-1997, the breaking strength (N) of the composite filter media flame-retardant filter cartridge is tested.

[0107] The test results are shown in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] As can be seen from Examples 1-4 and Comparative Examples 1-4, and Table 1, compared with Examples 1-3, the stiffness, dust removal rate, and tensile strength of Comparative Examples 1-2 are significantly reduced. Compared with Example 4, the stiffness, dust removal rate, and tensile strength of Comparative Examples 3-4 are significantly reduced. This indicates that using ES fiber or a fiber raw material composed of two fibers with different melting points, and employing the preparation methods of Examples 1 or 4, can improve the stiffness, tensile strength, and dust removal rate of the filter media.

[0112] Based on Examples 4-8 and Table 1, it can be seen that among Examples 4-8, Example 5 has the lowest stiffness and breaking strength, while Example 8 has lower stiffness and breaking strength than Example 7. This indicates that within a weight ratio of polyester fiber to PP fiber of 10:(4-8), the stiffness and breaking strength of the filter media can be further improved.

[0113] As can be seen from Examples 4 and 9-13 and Table 1, compared with Example 4, Examples 9-13 have greater stiffness and tensile strength, and their dust removal rates are all above 99.9%. This indicates that filter media with good stiffness, tensile strength, and dust removal rate can also be prepared using the fiber raw materials or process conditions of Examples 9-13.

[0114] As can be seen from Examples 4 and 14-21 and Table 1, compared with Example 4, the stiffness and breaking strength of Examples 14-21 are significantly increased. This indicates that the PP fibers prepared using Examples 14-21 help to further improve the stiffness and breaking strength of the filter media.

[0115] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing rigid filter media for filter cartridges without adhesive, characterized in that, Includes the following steps: Filter media preparation: The fiber raw materials are opened, blended, carded, laid into a web, and needle-punched to form a filter media layer; Reinforcement: The filter media layer is reinforced with hydroentangling to obtain felt material; Stiffening process: The fiber raw materials include A fiber and PP fiber. The A fiber is any one of polyester fiber, PPS fiber, aramid fiber, and PI fiber. The felt material is heated to 90-110℃; hot-rolled for 30-60 seconds and cooled to room temperature to obtain stiff filter material for filter cartridges.

2. The method for preparing a rigid filter media for filter cartridges without adhesive according to claim 1, characterized in that, The weight ratio of A fiber to PP fiber in the fiber raw material is 1:(0.4-0.8).

3. The method for preparing a rigid filter media for filter cartridges without adhesive according to claim 1, characterized in that, The PP fiber is prepared according to the following steps: After cleaning and drying the PP masterbatch, it is mixed with glycidyl methacrylate and benzoyl peroxide, heated to 150-180℃, and melt-blended to obtain the melt material. The molten material is electrospun to obtain PP fibers.

4. The method for preparing a rigid filter media for filter cartridges without adhesive according to claim 3, characterized in that, The weight ratio of the PP masterbatch, glycidyl methacrylate, and benzoyl peroxide is 100:(5-15):(0.1-0.25).

5. The method for preparing a rigid filter media for filter cartridges without adhesive according to claim 3, characterized in that, The PP masterbatch comprises the following raw materials in parts by weight: 80-100 parts PP resin, 10-20 parts ethoxylated alkylamine, 3-8 parts plasticizer, and 2-5 parts stabilizer.

6. A method for preparing a rigid filter media for filter cartridges without adhesive according to claim 5, characterized in that, The plasticizer is diisononyl phthalate.

7. A method for preparing a rigid filter media for filter cartridges without adhesive according to claim 5, characterized in that, The stabilizer comprises zinc stearate and hindered amine in a weight ratio of 1:(0.6-1.2).

8. A method for preparing a rigid filter media for filter cartridges without adhesive according to claim 5, characterized in that, The PP masterbatch is prepared according to the following steps: PP resin, ethoxylated alkylamine, plasticizer and stabilizer are mixed evenly to obtain a mixture; The mixture is melt-blended to obtain a melt; The melt is extruded and granulated to obtain PP masterbatch.

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