Ultralow-emission flame-retardant composite filter material
By employing a composite structure of polyimide nanofiber membrane and polydimethylsiloxane layer and a multi-layer fiber design in the bag filter media, the problems of bag deformation and insufficient flame retardancy under high temperature environments are solved, achieving a high-efficiency and high-temperature resistant filtration effect.
Patent Information
- Application Number
- CN202421972473.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-15
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2034-08-15
AI Technical Summary
Existing bag filter media are prone to deformation and breakage under high temperature environments, and their flame retardant properties are insufficient, failing to effectively block sparks, resulting in a decline in filtration performance.
A polyimide nanofiber membrane was prepared by electrospinning, using a polyimide nanofiber membrane as the coating layer and forming a polydimethylsiloxane layer on its surface, combined with a flame-retardant fiber layer and a multi-layer fiber structure, including a base fabric layer. High-temperature resistant materials and flame-retardant fibers were used to form a multi-layer composite structure.
It achieves high temperature resistance, flame retardancy, and high-efficiency filtration of filter media at high temperatures, ensuring filtration accuracy and mechanical strength, avoiding burns from sparks, and maintaining high-efficiency filtration performance for a long time.
Smart Images
Figure CN223887617U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to dust removal equipment filter material technical field more specifically, relate to a kind of super-low emission flame-retardant composite filter material. BACKGROUND
[0002] With the improvement of environmental awareness, super-low emission has become the inevitable requirement of waste incineration power generation industry, so bag filter plays an important role, and bag as the key accessory of filtration needs to be designed according to complex working conditions and problems. The usual requirements of bag are high filtration accuracy, high temperature resistance, chemical corrosion resistance, good hydrophobicity and high mechanical strength, and when applied in high temperature environment such as waste incineration, the boiler flue gas produced after incineration may carry incomplete combustion products and sparks, resulting in bag burning, so the bag is also required to have good flame retardancy.
[0003] The commonly used bag at present adopts polytetrafluoroethylene (PTFE) coated filter material, the surface is PTFE microporous membrane, the membrane is made by two-way stretching method, the membrane micropore morphology is point-line structure composed of "fiber" and "node", and the fiber diameter is uniform. Because the "fiber" constituting the membrane micropore structure is too fine and fragile, it is easy to deform or break during use, which causes the membrane micropore diameter to increase and the filtration performance to decrease; and when the use temperature exceeds 260℃, the PTFE material may creep during use, which may cause the pore size of PTFE membrane to change and the mechanical properties to decrease significantly; in addition, when the spark contacts the surface of the filter material, the membrane and the filter material may be burned through, resulting in the bag being unable to continue to be used. CONTENT OF THE UTILITY MODEL
[0004] The utility model aims at providing a super-low emission flame-retardant composite filter material with high filtration accuracy, good high temperature resistance and flame retardancy, which is suitable for waste incineration, biomass combustion and other working conditions.
[0005] To achieve the above purpose, the solution of the utility model is as follows:
[0006] A super-low emission flame-retardant composite filter material comprises, from the dust-approaching surface to the bottom, a polyimide nanofiber membrane with a polydimethylsiloxane layer on the surface, a flame-retardant fiber layer, a first fiber layer, a base cloth layer and a second fiber layer.
[0007] Further, the polydimethylsiloxane layer is formed by vapor deposition of methylsiloxane on the surface of the polyimide nanofiber membrane.
[0008] Further, the polyimide nanofiber membrane is made by electrospinning method, and the membrane is composed of thick and thin fibers alternately, and there is no node on the membrane.
[0009] Further, the polyimide fiber diameter of the polyimide nanofiber membrane is 50-800 nm, and the membrane pore size is 0.5-30 μm.
[0010] Furthermore, the flame-retardant fiber layer is made of boron nitride fiber, alumina fiber, or PAN pre-oxidized fiber, with a fiber fineness of 0.5dtex-2.2dtex and a length of 30mm-65mm.
[0011] Furthermore, the fiber materials of the first fiber layer and the second fiber layer are respectively glass fiber, basalt fiber, polyimide fiber, PTFE fiber or modified polyphenylene sulfide fiber, with a fiber fineness of 1.0dtex-2.2dtex and a length of 48mm-76mm.
[0012] Furthermore, the base fabric layer is either basalt fiber or glass fiber, and the basis weight of the base fabric layer is 100 g / m². 2 -420g / m 2 .
[0013] Furthermore, the flame-retardant fiber layer is produced by needle punching to obtain a flame-retardant fiber felt with a thickness of 1.0mm-2.0mm and a basis weight of 100g / m². 2 -200g / m 2 The base fabric layer, the first fiber layer, the second fiber layer, and the flame-retardant fiber felt are needle-punched together to form the first composite needle-punched felt, with a thickness of 3.0mm-5.0mm and a basis weight of 600g / m². 2 -950g / m 2 The first composite needle-punched felt, after being reinforced by hydroentangling, has a thickness of 1.8mm-3.5mm and a breaking strength of ≥900N / 5cm in the transverse direction and ≥1200N / 5cm in the longitudinal direction.
[0014] Furthermore, a polydimethylsiloxane layer is added to the surface of the polyimide nanofiber membrane to form a composite membrane layer, which is then composited onto the surface of the flame-retardant fiber layer.
[0015] By adopting the above solution, this utility model has at least the following technical effects:
[0016] 1. Using a polyimide nanofiber membrane with a polydimethylsiloxane layer as the coating layer not only blocks most dust and has filtration capabilities, but also has high mechanical strength, air permeability, and hydrophobicity. Furthermore, polyimide has better high-temperature resistance than commonly used PTFE; the polyimide nanofiber membrane can operate at temperatures up to 300℃ without undergoing high-temperature creep. Meanwhile, polydimethylsiloxane compensates for the lack of flame retardancy in conventional polyimide nanofiber membranes. The polydimethylsiloxane-polyimide nanofiber composite membrane layer formed by the polydimethylsiloxane layer and the polyimide nanofiber membrane simultaneously possesses high-temperature resistance and flame retardancy. It does not deform when exposed to flames and can protect the filter media from being burned or even burned through when sparks come into contact with it.
[0017] 2. The flame-retardant fiber layer further ensures the flame-retardant effect of the filter material and prevents sparks from burning the first fiber layer, the base fabric layer, and the second fiber layer.
[0018] 3. The first and second fiber layers can trap a small amount of infiltrated dust, improve filtration accuracy, and ensure ultra-low emissions of the filter media; the base fabric layer, as a support layer, mainly plays a supporting and reinforcing role, improving the tensile strength of the filter media.
[0019] 4. Polyimide nanofiber membranes consist of at least one layer composed of alternating coarse and fine fibers, resulting in better filtration compared to membranes with uniform fiber diameter; moreover, the membranes have no nodes, providing better air permeability, higher strength, and resistance to deformation or breakage.
[0020] 5. The materials used in the filter media of this utility model all have good high temperature resistance, and can continuously and efficiently filter in high temperature environments, with a filtration efficiency of up to 99.99%. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the layer structure of this utility model;
[0022] Figure 2 This is a schematic cross-sectional view of a polyimide nanofiber membrane with a polydimethylsiloxane layer formed on its surface.
[0023] Explanation of reference numerals: 1. Polyimide nanofiber membrane with a polydimethylsiloxane layer formed on the surface; 2. Flame retardant fiber layer; 3. First fiber layer; 4. Base fabric layer; 5. Second fiber layer. Detailed Implementation
[0024] To further explain the technical solution of this utility model, the following detailed description is provided through specific embodiments.
[0025] See Figure 1 This utility model discloses an ultra-low emission flame-retardant composite filter material, which includes, from top to bottom, the following components from the dust-facing side: a polyimide nanofiber membrane 1 with a polydimethylsiloxane layer formed on its surface, a flame-retardant fiber layer 2, a first fiber layer 3, a base fabric layer 4, and a second fiber layer 5.
[0026] In this process, a composite film layer (PDMS@PI nanofiber membrane coating) is formed by adding a polydimethylsiloxane (PDMS) layer to the surface of a polyimide nanofiber membrane (PI). The PDMS layer can be formed by chemical vapor deposition of methylsiloxane on the surface of the polyimide nanofiber membrane, thus possessing the characteristics of both polyimide nanofiber membrane and PDMS. (See also...) Figure 2The polyimide nanofiber membrane is prepared by electrospinning and consists of a dense polyimide fiber web. The diameter of the membrane fibers is adjustable, and the alternating coarse and fine fibers create a membrane with better filtration compared to membranes with uniform fiber diameter. Furthermore, the membrane has no nodes, resulting in better air permeability. Because the polyimide nanofiber membrane can be spun into multiple layers from coarse and fine fibers, its strength is higher than that of PTFE membranes. In addition, the membrane material is polyimide, which has better high-temperature resistance than PTFE, with an operating temperature up to 300℃ and no high-temperature creep. The polyimide fiber diameter of the polyimide nanofiber membrane in this invention is 50nm-800nm, and the membrane pore size is 0.5μm-30μm. However, conventional polyimide nanofiber membranes are slightly lacking in flame retardancy. Therefore, in this invention, polydimethylsiloxane with flame retardant properties is vapor-deposited on the surface of polyimide nanofibers to obtain a PDMS@PI nanofiber membrane with good flame retardancy that does not deform when exposed to flame. At the same time, the PDMS@PI nanofiber membrane also has good hydrophobicity.
[0027] The polyimide nanofiber membrane with a polydimethylsiloxane layer on its surface is composited on the surface (dust-facing side) of the flame-retardant fiber layer. The flame-retardant fiber layer 2 is made of one or more types of fibers, including but not limited to boron nitride fibers, alumina fibers, or PAN pre-oxidized fibers, with a fiber fineness of 0.5 dtex-2.2 dtex and a length of 30 mm-65 mm. The flame-retardant fiber layer further ensures the flame-retardant effect of the filter media.
[0028] The first fiber layer 3 and the second fiber layer 5 of this invention are made of one or more types of fibers, including but not limited to: glass fiber, basalt fiber, polyimide fiber, PTFE fiber, and modified polyphenylene sulfide fiber. The fiber fineness is 1.0 dtex-2.2 dtex, and the length is 48 mm-76 mm. The base fabric layer 4 can be a basalt fiber base fabric or a glass fiber base fabric, and the base fabric layer has a basis weight of 100 g / m². 2 -420g / m 2 .
[0029] The aforementioned first fiber layer, base fabric layer, and second fiber layer are all high-temperature resistant materials. Therefore, this utility model, by employing a PDMS@PI nanofiber membrane 1 and a flame-retardant fiber layer 2 on the surface, and setting a first fiber layer 3, a base fabric layer 4, and a second fiber layer 5, forms a multi-layer filter material structure. This results in a filter material that not only has high filtration accuracy and good high-temperature resistance, but also excellent flame retardancy, making it widely applicable in waste incineration, biomass combustion, and other similar applications.
[0030] To further illustrate the structural relationship between the layers of this utility model, the preparation method of the ultra-low emission flame-retardant composite filter material of this utility model is as follows:
[0031] At least one of the following fibers is preferred: boron nitride fiber, alumina fiber, and PAN pre-oxidized fiber. A fiber mat with a thickness of approximately 1.0 mm to 2.0 mm is prepared by needle punching and used as the flame-retardant fiber layer, with a basis weight of 100 g / m². 2 -200g / m 2 ;
[0032] Basalt fiber base fabric or glass fiber base fabric is preferred as the base fabric layer;
[0033] Preferably, one or more fibers selected from glass fiber, basalt fiber, polyimide fiber, PTFE fiber or modified polyphenylene sulfide fiber are used as the first fiber layer and the second fiber layer.
[0034] The first fiber layer, base fabric layer, and second fiber layer are combined with a fiber felt serving as a flame-retardant fiber layer through a needle-punching pretreatment process to obtain a first composite needle-punched felt with certain mechanical and filtration properties. The thickness of the first composite needle-punched felt is 3.0 mm-5.0 mm, and the basis weight is 600 g / m². 2 -950g / m 2 ;
[0035] The first composite needle-punched felt is then reinforced using hydroentangling technology to form a second composite needle-punched felt with a thickness of 1.8mm-3.5mm. Its tensile strength is ≥900N / 5cm in the transverse direction and ≥1200N / 5cm in the longitudinal direction. This step makes the fiber entanglement tighter and the pores of the filter material smaller.
[0036] Finally, a polyimide nanofiber membrane (PDMS@PI nanofiber membrane) with a polydimethylsiloxane layer on its surface is laminated onto the dust-facing side of the flame-retardant fiber layer. For example, PTFE emulsion or other high-temperature resistant reagents can be added to bond the flame-retardant fiber layer and the PDMS@PI nanofiber membrane, thereby improving the filtration accuracy of the filter media while enhancing its flame-retardant properties.
[0037] The above is merely one embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A low-emission flame-retardant composite filter material, characterized in that: From top to bottom, the dust-facing surface includes: a polyimide nanofiber membrane with a polydimethylsiloxane layer formed on its surface, a flame-retardant fiber layer, a first fiber layer, a base fabric layer, and a second fiber layer; the polydimethylsiloxane layer is formed by vapor deposition of methylsiloxane on the surface of the polyimide nanofiber membrane.
2. The ultra-low emission flame-retardant composite filter material according to claim 1, characterized in that: The polyimide nanofiber membrane is prepared by electrospinning, with alternating coarse and fine fibers forming the membrane, and there are no nodes on the membrane.
3. The ultra-low emission flame-retardant composite filter material according to claim 2, characterized in that: The polyimide nanofiber membrane has a polyimide fiber diameter of 50nm-800nm and a membrane pore size of 0.5μm-30μm.
4. The ultra-low emission flame-retardant composite filter material according to claim 1, characterized in that: The flame-retardant fiber layer is made of boron nitride fiber, alumina fiber or PAN pre-oxidized fiber, with a fiber fineness of 0.5dtex-2.2dtex and a length of 30mm-65mm.
5. The ultra-low emission flame-retardant composite filter material according to claim 1, characterized in that: The first and second fiber layers are made of one of the following materials: glass fiber, basalt fiber, polyimide fiber, PTFE fiber, or modified polyphenylene sulfide fiber, with a fiber fineness of 1.0 dtex-2.2 dtex and a length of 48 mm-76 mm.
6. The ultra-low emission flame-retardant composite filter material according to claim 1, characterized in that: The base fabric is either basalt fiber or glass fiber, with a basis weight of 100 g / m². 2 -420g / m 2 .
7. The ultra-low emission flame-retardant composite filter material according to claim 1, characterized in that: The flame-retardant fiber layer is produced by needle punching to obtain a flame-retardant fiber felt with a thickness of 1.0mm-2.0mm and a basis weight of 100g / m². 2 -200g / m 2 The base fabric layer, the first fiber layer, the second fiber layer, and the flame-retardant fiber felt are needle-punched together to form the first composite needle-punched felt, with a thickness of 3.0mm-5.0mm and a basis weight of 600g / m². 2 -950g / m 2 The first composite needle-punched felt, after being reinforced by hydroentangling, has a thickness of 1.8mm-3.5mm and a breaking strength of ≥900N / 5cm in the transverse direction and ≥1200N / 5cm in the longitudinal direction.
8. The ultra-low emission flame-retardant composite filter material according to claim 1 or 7, characterized in that: A composite film is formed by adding a polydimethylsiloxane layer to the surface of a polyimide nanofiber membrane, which is then further composited onto the surface of a flame-retardant fiber layer.