Composite short fiber for air filter and preparation method thereof

Abstract

The application discloses a kind of composite short fibers for air filter, comprising: fiber matrix, the fiber matrix is made of first polymer;The surface of fiber matrix is equipped with multiple recessed grooves;Two recessed grooves between adjacent form protruding rib part;The top of protruding rib part is covered with low melting point layer, the low melting point layer is made of second polymer;The melting point of first polymer is higher than the melting point of second polymer by 40-100 DEG C.The application leaves larger pore and filter area for filter material, so that the filter material can obtain high porosity, and has low damping and resilience and rigidity.Meanwhile, the three-lobed main body in three-lobed cross section is mixed with antibacterial material, which gives the fiber long-term safe broad-spectrum antibacterial, antiviral, mildew-proof, odor-removing function.

Description

Technical Field

[0001] This invention belongs to the field of short fiber composite spinning, specifically relating to a composite short fiber for air filters and its preparation method. Background Technology

[0002] Air purification is an essential part of air purification engineering, and it is the most effective method for eliminating indoor air pollution under modern conditions. In addition to requiring significant purification effects, ease of use, and safety, air purification materials also need broad-spectrum antibacterial and antiviral properties.

[0003] Traditional air purification filter media are made of polyester and polypropylene short fibers, with coarse denier short fibers as the skeleton and fine denier short fibers as the filter substrate, and are formed by hot pressing together low-melting-point short fibers. In this traditional method of hot bonding low-melting-point short fibers, the low-melting-point short fibers are not evenly dispersed within the polyester and polypropylene short fibers during filter media processing. The areas where the low-melting-point short fibers are clustered are too tightly bonded, resulting in an excessively large bonding area with no filtration pores, leading to a lack of airflow in the bonded areas. Conversely, the sparse areas of the low-melting-point short fibers are not sufficiently bonded, resulting in significant differences in filtration accuracy and making it difficult to achieve uniform filtration performance.

[0004] With the increasing demand for a high-quality life, air purification requires antibacterial properties, creating a market need for antibacterial short fibers used in air purification filter materials.

[0005] In summary, the following technical issues urgently need to be addressed in air purification filter materials: 1. While ensuring uniform filtration accuracy, improve adhesion to achieve good fiber formation, thereby increasing the material's porosity, improving air permeability, and reducing filtration resistance; 2. Ensure that the short fibers in contact with air have long-lasting and broad-spectrum antibacterial and antiviral effects to meet the antibacterial and antiviral requirements of air filter materials. Summary of the Invention

[0006] In view of the shortcomings of existing technology, the purpose of this invention is to provide a trilobal composite short fiber for air filters and its preparation method. By comprehensively utilizing the trilobal composite fiber structure and providing a low-melting-point component at the tip of the trilobes, the protruding parts of the fiber cross-section can be thermally bonded in a line-contact manner during the hot rolling process of manufacturing air purification filter media. This bonding is uniform and maximizes the preservation of the concave structure of the trilobal cross-section, providing a larger pore size and filtration area for the filter media. This results in high porosity, low damping, resilience, and rigidity. Simultaneously, antibacterial materials are incorporated into the trilobal body of the cross-section, endowing the fiber with long-lasting, safe, broad-spectrum antibacterial, antiviral, anti-mildew, and deodorizing functions. The technical solution adopted by this invention to solve its technical problem is as follows: A composite short fiber for air filters, comprising: A fiber matrix, the fiber matrix being made of a first polymer; the surface of the fiber matrix having multiple recessed grooves; and a protruding rib being formed between two adjacent recessed grooves; The top of the protruding rib is covered with a low-melting-point layer, which is made of a second polymer; The melting point of the first polymer is 40-100°C higher than that of the second polymer.

[0007] Optionally, the fiber matrix contains an antibacterial material; Preferably, the antibacterial material is at least one of nano-copper carbon, nano-zinc oxide, and graphene; Preferably, the content of antibacterial material in the fiber matrix is ​​400-2000 ppm; Preferably, the fiber matrix further contains a dispersant and an antioxidant.

[0008] Optionally, the first polymer is at least one of high-melting-point polyester and polypropylene; the melting point of the first polymer is 250°C to 258°C. Preferably, the second polymer is at least one of low-melting-point polyester and polypropylene; the melting point of the second polymer is 150°C to 180°C.

[0009] Optionally, the fiber matrix surface is provided with 3 recessed grooves, and 3 protruding ribs are formed between the recessed grooves on the fiber matrix surface.

[0010] Optionally, the weight ratio of the first polymer to the second polymer is 55-70:30-45.

[0011] Optionally, the fiber matrix further includes a dispersant and an antioxidant; The dispersant is a low molecular weight polyester LMPET or PET wax, or a titanate coupling agent, etc. The antioxidant is a hindered phenolic antioxidant, such as pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate).

[0012] An apparatus for manufacturing composite short fibers for air filters, comprising: The spinneret has spinneret holes, which are provided with guide grooves, trilobal guide holes, transition holes, and trilobal micro-orifice units. The guide grooves expand around the trilobal guide holes, and the trilobal guide holes, transition holes, and trilobal micro-orifice units are interconnected. The ends of the trilobal shapes have a semi-circular arc structure. The distribution plate has an A-component flow channel and a B-component flow channel; the B-component flow channel is provided with a B-component through-flow hole at the position corresponding to the spinneret guide groove; the A-component flow channel is provided with three A-component through-flow holes on the inner side of the semi-circular arc at the top of the spinneret's three-lobe guide hole, and the outlet end of the A-component through-flow hole is three extended needle tubes that are inserted into the inner side of the semi-circular arc at the top of the spinneret's three-lobe guide hole. The high-melting-point B-component fiber-forming polymer melt flows into the spinneret guide groove through the B-component through-through guide hole of the distribution plate and gathers into the trilobal guide hole; the low-melting-point A-component fiber-forming polymer melt flows into the inner side of the semi-circular arc of the trilobal guide hole through the three needle tubes in the A-channel of the distribution plate.

[0013] Optionally, the included angle of the three lobes of the trilobal guide hole is 120°, the width of the lobes is 0.08-0.16 mm, and the aspect ratio of the lobes is 3-6; the insertion depth of the needle into the trilobal guide hole is 0.5-1.5 mm. The spinneret and the distribution plate are hard-sealed at their mating surfaces, with a surface roughness of 0.1-0.25 micrometers.

[0014] A method for preparing composite short fibers for air filters includes the following steps: Using a masterbatch injection device, an antibacterial masterbatch containing antibacterial material is melted and injected into the melt of the first polymer to form a high-melting-point B-component fiber-forming polymer melt; the second polymer is melted to obtain a low-melting-point A-component fiber-forming polymer melt; the high-melting-point B-component fiber-forming polymer melt and the low-melting-point A-component fiber-forming polymer melt are respectively injected into the above-mentioned device for manufacturing composite short fibers for air filters, and the composite spinning process is used to obtain the composite short fibers for air filters.

[0015] Optionally, the method for preparing the antimicrobial masterbatch containing antimicrobial material includes: blending, melting, and kneading antimicrobial material powder with a first polymer at a weight ratio of 1 to 4:10 to prepare antimicrobial masterbatch.

[0016] The antibacterial masterbatch is dried in a vacuum drum until the moisture content is below 50 ppm. Then, the antibacterial melt is injected into the high-melting-point fiber-forming polymer melt of component B using a masterbatch injection device to achieve secondary dispersion.

[0017] The beneficial effects of this invention include: This invention discloses a trilobal composite short fiber for air filters and its preparation method. It designs a trilobal cross-section composite short fiber, a trilobal composite spinneret, and a distribution plate. The fiber cross-section contains two fiber-forming polymers with different melting points. The fiber cross-section is trilobal in shape, consisting of a trilobal body (component B) and a trilobal tip (component A). The trilobal body and the trilobal tip polymer are bonded together by interfacial forces, but have different melting points. By comprehensively utilizing the trilobal composite fiber structure and providing a low-melting-point component at the trilobal tip, the protruding parts of the fiber cross-section can be thermally bonded in a line-contact manner during the hot rolling process of manufacturing air purification filter media. The bonding is uniform, maximizing the preservation of the concave structure of the trilobal cross-section. This provides the filter media with larger pores and filtration area, enabling the filter media to achieve high porosity, low damping, resilience, and rigidity. Simultaneously, antibacterial materials are incorporated into the trilobal body of the trilobal cross-section, endowing the fiber with long-lasting, safe, broad-spectrum antibacterial, antiviral, anti-mildew, and deodorizing functions. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a trilobal composite fiber cross-section structure provided in one embodiment of the present invention; Figure 2 This is a top view of the spinneret of the present invention; Figure 3 This is a top view of the distribution plate of the present invention; Figure 4 This is a cross-sectional view (including the structure with holes) of the spinneret and distribution plate assembly of the present invention. Figure 5 This is an indicator of the antibacterial properties of antibacterial fibers. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0021] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] First, this invention proposes a composite short fiber for air filters, comprising: A fiber matrix, the fiber matrix being made of a first polymer; the surface of the fiber matrix having multiple recessed grooves; and a protruding rib being formed between two adjacent recessed grooves; The top of the protruding rib is covered with a low-melting-point layer, which is made of a second polymer; The melting point of the first polymer is 40-100°C higher than that of the second polymer. Preferably, the melting point of the first polymer is 60-90°C higher than that of the second polymer. Furthermore, the fiber matrix contains antibacterial materials; Preferably, the antibacterial material is at least one of nano-copper carbon, nano-zinc oxide, and graphene; The preferred antibacterial material used is nano-copper-carbon material. This utilizes copper ions (Cu²⁺). + The antibacterial mechanism of this invention involves inhibiting or killing microorganisms by disrupting bacterial cell walls, inducing lipid peroxidation, and DNA degradation. Due to the encapsulation and stabilizing effect of the carbon matrix, the copper component is not easily released rapidly, achieving a long-lasting, slow-release antibacterial effect while reducing potential toxicity to the environment and human body. In this invention, the trilobal body of the trilobal composite short fiber is always in contact with purified air, forming a stable Cu=Cu2O equilibrium system during use. This system exhibits excellent chemical and physical stability, primarily using contact killing as the main mode of microbial control, achieving an environmentally friendly, eco-friendly, and human-friendly antibacterial (sterilizing) and antiviral system. This invention utilizes copper-carbon antibacterial materials from Suzhou Guanjie Company.

[0025] Preferably, the content of antibacterial material in the fiber matrix is ​​400-2000 ppm; more preferably, it is 500-1000 ppm.

[0026] Preferably, the fiber matrix further contains a dispersant and an antioxidant.

[0027] The first polymer is at least one of high-melting-point polyester and polypropylene; the second polymer is at least one of low-melting-point polyester, polypropylene, and polyethylene; the melting point of the first polymer is 250℃~258℃; the melting point of the second polymer is 150℃~180℃.

[0028] Furthermore, the fiber matrix surface is provided with 3 recessed grooves, and 3 protruding ribs are formed between the recessed grooves on the fiber matrix surface, forming an overall trilobal shape.

[0029] Furthermore, the weight ratio of the first polymer to the second polymer is 55-70:30-45.

[0030] Furthermore, the fiber matrix also contains dispersants and antioxidants; The dispersant is a low molecular weight polyester LMPET or PET wax, or a titanate coupling agent, etc. The antioxidant is a hindered phenolic antioxidant, such as pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate).

[0031] The present invention also proposes an apparatus for manufacturing composite short fibers for air filters, comprising: The spinneret 2 has spinneret holes, which are provided with a guide groove 21, a trilobal guide hole 22, a transition hole, and a trilobal micro-orifice unit 23. The guide groove 21 expands around the trilobal guide hole 22, and the trilobal guide hole, transition hole, and trilobal micro-orifice unit are interconnected. The end of the trilobal guide hole 22 has a semi-circular arc structure. The distribution plate 1 has an A component flow channel 12 and a B component flow channel 11; the B component flow channel is provided with a through flow guide hole at the position corresponding to the spinneret guide groove; the A component flow channel is provided with three through flow guide holes on the inner side of the semi-circular arc at the top of the spinneret's three-lobe guide hole; the outlet end of the through flow guide hole is three extended needle tubes 13, which are inserted into the inner side of the semi-circular arc at the top of the spinneret's three-lobe guide hole; The high-melting-point B-component fiber-forming polymer melt flows into the spinneret guide groove through the through-through guide hole in the distribution plate B channel and gathers into the trilobal guide hole; the low-melting-point A-component fiber-forming polymer melt flows into the inner side of the semi-circular arc of the trilobal guide hole through the three needle tubes in the distribution plate A channel.

[0032] Furthermore, the included angle of the three lobes of the trilobal guide hole is 120°, the width of the lobes is 0.08-0.16mm, and the aspect ratio of the lobes is 3-6; the insertion depth of the needle into the trilobal guide hole is 0.5-1.5mm. The spinneret and the distribution plate are hard-sealed at their mating surfaces, with a surface roughness of 0.1-0.25 micrometers.

[0033] This invention also proposes a method for preparing composite short fibers for air filters, comprising the following steps: The apparatus for manufacturing composite short fibers for air filters is mounted on the masterbatch injection unit; The antibacterial masterbatch is melted and injected into a high-melting-point melt through a masterbatch injection device to form a blended component B. Then, it undergoes composite spinning with the fiber-forming polymer melt of component A, metering, quenching, oiling, yarn guiding, feeding into the bobbin, bundling, balancing, stretching, crimping, drying and shaping, cutting, and packaging.

[0034] Furthermore, the method for preparing the antibacterial masterbatch includes: blending, melting, and kneading the antibacterial powder with the first polymer at a ratio of 10% to 40% to prepare the antibacterial masterbatch; The antibacterial masterbatch is dried in a vacuum drum until the moisture content is below 50 ppm. Then, the antibacterial melt is injected into the high-melting-point fiber-forming polymer melt of component B using a masterbatch injection device to achieve secondary dispersion.

[0035] Furthermore, the winding speed of the short fibers is 1000-1500 m / min, and the draw ratio is 3-5 times. The prepared trilobal composite short fibers have a specification of 1.1 dtex-3.75 dtex, a cut length of 38-76 mm, a breaking strength of 3.5-4.5 cN / dtex, a breaking elongation of 25%-35%, and a crimp of 5-10 crimps / cm.

[0036] Example 1 Firstly, this invention proposes, as follows: Figure 1 The air filter uses a trilobal composite short fiber. The fiber cross-section contains two fiber-forming polymers with different melting points. The fiber cross-section is trilobal, consisting of a trilobal body (component B) and a trilobal tip (component A). Component B is a high-melting-point polyester (PET) with a melting point of 258°C, and contains 1000 ppm of antibacterial material (copper-carbon material). Component A is a low-melting-point polyester (Co-PET) with a melting point of 180°C. As shown in the figure, the surface of the trilobal body of component B has multiple recessed grooves (b1) in an arc shape. A protruding rib (b2) is formed between two adjacent recessed grooves (b2). The tip of each protruding rib is covered with a low-melting-point layer of component A.

[0037] This embodiment further proposes an apparatus for manufacturing composite short fibers for air filters, such as... Figures 2-4 As shown, it includes: The spinneret has spinneret holes, which are provided with guide grooves, trilobal guide holes, transition holes, and trilobal micro-orifice units. The guide grooves expand around the trilobal guide holes, and the trilobal guide holes, transition holes, and trilobal micro-orifice units are interconnected. The ends of the trilobal shapes have a semi-circular arc structure. The distribution plate has an A-component flow channel and a B-component flow channel; the B-component flow channel has a through-flow guide hole at the position corresponding to the spinneret guide groove; the A-component flow channel has three through-flow guide holes on the inner side of the semi-circular arc at the top of the spinneret's three-lobe guide hole; the outlet end of the through-flow guide hole is three extended needle tubes that are inserted into the inner side of the semi-circular arc at the top of the spinneret's three-lobe guide hole.

[0038] The present invention also proposes a method for preparing trilobal composite short fibers for air filters using the above-mentioned apparatus: Using a masterbatch injection device, antibacterial masterbatch containing antibacterial materials is melted and injected into a high-melting-point polyester (PET) melt to form a high-melting-point B-component fiber-forming polymer melt, in which the antibacterial powder content is 1000ppm; after melting the low-melting-point polyester (Co-PET), a low-melting-point A-component fiber-forming polymer melt is obtained. High-melting-point component B fiber-forming polymer melt and low-melting-point component A fiber-forming polymer melt are respectively injected into the aforementioned apparatus for manufacturing composite short fibers for air filters, and the composite spinning process yields the composite short fibers for air filters. The high-melting-point component B fiber-forming polymer melt flows into the spinneret guide groove through the through-flow guide hole in the distribution plate B channel, and converges into the trilobal guide hole; the low-melting-point component A fiber-forming polymer melt flows into the inner side of the semi-circular arc of the trilobal guide hole through three needle tubes in the distribution plate A channel. The processing steps include composite spinning, metering, quenching, oiling, guiding, feeding to the bobbin, bundling, balancing, drawing, crimping, drying and setting, cutting, and packaging.

[0039] The tri-blade composite spinneret used has 1200 holes, with each micro-perforated unit having a blade width of 1.2 mm, a length-to-width ratio of 4.8, a tri-blade angle of 120°, and semi-circular tips. The needle insertion depth of the distribution plate is 1.2 mm. The weight ratio of components A to B is 30:70, meaning each blade tip contains 10 parts of low-melting-point polymer. The prepared tri-blade composite short fiber has a strength of 3.3 dtex, a cut length of 51 mm, a breaking strength of 4.0 cN / dtex, a breaking elongation of 31%, and a crimp of 8 fibers / cm.

[0040] Example 2 Compared with Example 1, the difference in this example is that: in this example, component B is high-melting-point polyester (PET) with a melting point of 258°C, and the antibacterial powder content in component B is 1000 ppm. Component A is polypropylene with a melting point of 170°C. The weight ratio of A to B components is 55:45, and the content of each low-melting-point polymer at the top is 15 parts. The rest of the implementation method is the same as in Example 1.

[0041] Example 3 Compared with Example 1, the method for manufacturing composite short fibers for air filters in this example differs in that: The antibacterial masterbatch is melted and injected into a high-melting-point melt using a masterbatch injection device to form a blended component B. This component then undergoes composite spinning with the fiber-forming polymer melt of component A, followed by metering, rapid cooling, oiling, yarn guiding, feeding into the bobbin, bundling, balancing, drawing, crimping, drying, shaping, cutting, and packaging. The preparation method of the antibacterial masterbatch includes: blending, melting, and compounding antibacterial powder (copper-carbon material) with a first polymer at a ratio of 20% to prepare the antibacterial masterbatch; the antibacterial masterbatch is vacuum drum dried until the moisture content is below 50 ppm, and then the antibacterial melt is injected into the high-melting-point fiber-forming polymer melt of component B using a masterbatch injection device to achieve secondary dispersion. Component B is a high-melting-point polyester with a melting point of 260°C. The copper-carbon antibacterial material powder content in the antibacterial masterbatch is 25%, and the antibacterial powder content in component B is 1200 ppm. Component A is a low-melting-point polyester with a melting point of 200°C.

[0042] The three-blade composite spinneret used has 1500 holes, the three-blade micro-hole unit has a blade width of 1.4 mm, the blade length-to-width ratio is 5, the included angle of the three blades is 120°, the end of the three blades is semi-circular, and the insertion depth of the needle tube of the distribution plate is 1.5 mm.

[0043] The high-melting-point B-component fiber-forming polymer melt flows into the spinneret guide groove through the B-component through-through guide hole of the distribution plate and gathers into the trilobal guide hole; the low-melting-point A-component fiber-forming polymer melt flows into the inner side of the semi-circular arc of the trilobal guide hole through the three needle tubes in the A-channel of the distribution plate.

[0044] The ratio of components A to B is 40:60, and the content of low-melting-point polymer at the tip of each leaf is 13.3 parts. The prepared trifoliate composite short fiber has a specification of 2.65 dtex, a cut length of 51 mm, a breaking strength of 3.8 cN / dtex, a breaking elongation of 28%, and a crimp of 10 crimps / cm.

[0045] The antibacterial properties of the material in this embodiment were tested, and the results are as follows: Figure 5 As shown.

[0046] Comparative Example 1 No antibacterial materials were added to the components in this comparative example.

[0047] This example still uses the apparatus from Example 2 to manufacture composite short fibers for air filters: Components A and B are melted and heated by a screw to form a polymer melt composite spinning process, including metering, rapid cooling, oiling, yarn guiding, feeding into the bobbin, bundling, balancing, drawing, crimping, drying, setting, cutting, and packaging. Component A is a low-melting-point polyester with a melting point of 180℃. Component B is a high-melting-point polyester with a melting point of 260℃. The three-blade composite spinneret used has 1500 holes, with each micro-perforated unit having a blade width of 1.4 mm, a length-to-width ratio of 5, an included angle of 120°, and semi-circular ends. The needle insertion depth of the distribution plate is 1.5 mm. The A:B component ratio is 40:60, and each blade tip contains 13.3 parts of low-melting-point polymer. The prepared three-blade composite short fiber has a specification of 3.3 dtex, a cut length of 51 mm, a breaking strength of 4.0 cN / dtex, a breaking elongation of 31%, and a crimp of 8 fibers / cm.

[0048] Experimental results show that the actual antibacterial rate of composite silk produced without the addition of antibacterial masterbatch is almost zero.

[0049] Comparative Example 2 Composite production is carried out using two different materials with the same melting point.

[0050] This example continues to use the apparatus from Example 2 to manufacture composite short fibers for air filters: The antibacterial masterbatch is melted and injected into a high-melting-point melt using a masterbatch injection device to form a blended component B. This component then undergoes a complex spinning process with the fiber-forming polymer melt of component A, including metering, rapid cooling, oiling, yarn guiding, feeding into the bobbin, bundling, balancing, stretching, crimping, drying, shaping, cutting, and packaging. The preparation method of the antibacterial masterbatch includes: blending, melting, and compounding antibacterial powder with a first polymer at a ratio of 10% to 40% to prepare the antibacterial masterbatch; drying the antibacterial masterbatch in a vacuum drum until the moisture content is below 50 ppm; then, using a masterbatch injection device, injecting the antibacterial melt into the high-melting-point fiber-forming polymer melt of component B to achieve secondary dispersion. Component B is a high-melting-point polyester with a melting point of 260°C. The antibacterial powder content in the antibacterial masterbatch is 25%, and the antibacterial powder content in component B is 1200 ppm. Component A is also a high-melting-point polyester with a melting point of 260°C. The tri-blade composite spinneret used has 1500 holes, with each micro-blade unit having a width of 1.4 mm, an aspect ratio of 5, an included angle of 120°, and semi-circular ends. The needle insertion depth of the distribution plate is 1.5 mm. The A:B component ratio is 40:60, and each blade tip contains 13.3 parts of low-melting-point polymer. The prepared tri-blade composite short fiber has a strength of 3.61 dtex, a cut length of 50 mm, a breaking strength of 3.0 cN / dtex, a breaking elongation of 25%, and a crimp of 7 fibers / cm.

[0051] The fibers from Examples 1 and 3, and Comparative Example 2, were fed, opened, carded, and cross-laid to form composite fiber webs. These composite fiber webs were then thermally bonded at 10 m / min through a hot air chamber at 130°C. After initial bonding with cold rollers, they were further shaped and reinforced by passing them through upper and lower hot rollers at 155°C / 155°C at a speed of 10 m / min, with a distance of 0.04 mm between the upper and lower hot rollers. Finally, a thermally bonded filter felt was obtained. Scanning electron microscopy revealed that the bonding of the three types of fibers differed, as shown in Table 1. Table 1

[0052] Experimental results show that although antibacterial masterbatch was added during production and the antibacterial effect met the requirements, the low bonding rate between fibers in the cross-section due to the same melting point of the two materials resulted in poor bonding and affected the filtration effect.

[0053] This application discloses a trilobal composite short fiber for air filtration and its preparation method. The invention designs a trilobal cross-section composite short fiber, a trilobal composite spinneret, and a distribution plate. The fiber cross-section contains two fiber-forming polymers with different melting points. The fiber cross-section is trilobal in shape, consisting of a trilobal body (component B) and a trilobal tip (component A). The trilobal body and the trilobal tip polymer are bonded together by interfacial forces, but have different melting points. By comprehensively utilizing the trilobal composite fiber structure and providing a low-melting-point component at the trilobal tip, the invention achieves a concave trilobal cross-section structure. This provides a larger pore size and filtration area for the filter material, enabling the filter material to achieve high porosity, low damping, resilience, and rigidity.

[0054] In the preparation of air purification filter media, the low-melting-point component A of the trilobal composite short fiber can be thermally bonded to ensure good filter media shaping, uniform filtration accuracy, high porosity, low filtration damping, and high tear resistance. Component B, representing the trilobal cross-section of the fiber, serves as the filter body and possesses broad-spectrum and highly effective antibacterial (sterilization) functions. Furthermore, the incorporation of antibacterial materials within the trilobal cross-section gives the fiber long-lasting, safe, broad-spectrum antibacterial, antiviral, anti-mildew, and deodorizing properties. The trilobal cross-section increases the filter media's purification area, improves filtration uniformity, and reduces air filtration resistance, making it a highly efficient antibacterial and antiviral air purification material widely used in various air purification applications.

[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A composite short fiber for air filters, characterized in that, include: A fiber matrix, the fiber matrix being made of a first polymer; the surface of the fiber matrix having multiple recessed grooves; and a protruding rib being formed between two adjacent recessed grooves; The top of the protruding rib is covered with a low-melting-point layer, which is made of a second polymer; The melting point of the first polymer is 40-100°C higher than that of the second polymer.

2. The composite short fiber for air filters according to claim 1, characterized in that, The fiber matrix contains antibacterial materials; Preferably, the antibacterial material is at least one of nano-copper carbon, nano-zinc oxide, and graphene; Preferably, the content of antibacterial material in the fiber matrix is ​​400-2000 ppm.

3. The composite short fiber for air filters according to claim 1, characterized in that, The first polymer is at least one of high-melting-point polyester and polypropylene; the second polymer is at least one of low-melting-point polyester, polypropylene, and polyethylene. Preferably, the melting point of the first polymer is 250°C to 258°C; Preferably, the melting point of the second polymer is 150°C to 180°C.

4. The composite short fiber for air filters according to claim 1, characterized in that, The fiber matrix surface has three recessed grooves, and three protruding ribs are formed between the recessed grooves on the fiber matrix surface.

5. The composite short fiber for air filters according to claim 1, characterized in that, The weight ratio of the first polymer to the second polymer is 55-70:30-45.

6. The composite short fiber for air filters according to claim 1, characterized in that, The fiber matrix also contains dispersants and antioxidants.

7. An apparatus for manufacturing composite short fibers for air filters, characterized in that, include The spinneret has spinneret holes, which are provided with guide grooves, trilobal guide holes, transition holes, and trilobal micro-orifice units. The guide grooves expand around the trilobal guide holes, and the trilobal guide holes, transition holes, and trilobal micro-orifice units are interconnected. The ends of the trilobal shapes have a semi-circular arc structure. The distribution plate has an A-component flow channel and a B-component flow channel; the B-component flow channel is provided with a B-component through-flow hole at the position corresponding to the spinneret guide groove; the A-component flow channel is provided with three A-component through-flow holes on the inner side of the semi-circular arc at the top of the spinneret's three-lobe guide hole, and the outlet end of the A-component through-flow hole is three extended needle tubes that are inserted into the inner side of the semi-circular arc at the top of the spinneret's three-lobe guide hole. The high-melting-point B-component fiber-forming polymer melt flows into the spinneret guide groove through the B-component through-through guide hole of the distribution plate and gathers into the trilobal guide hole; the low-melting-point A-component fiber-forming polymer melt flows into the inner side of the semi-circular arc of the trilobal guide hole through the three needle tubes in the A-channel of the distribution plate.

8. The apparatus for manufacturing composite short fibers for air filters according to claim 7, characterized in that, The included angle of the three lobes of the trilobed guide hole is 120°, the width of the lobes is 0.08-0.16mm, and the aspect ratio of the lobes is 3-6; the insertion depth of the needle into the trilobed guide hole is 0.5-1.5mm. The spinneret and the distribution plate are hard-sealed at their mating surfaces, with a surface roughness of 0.1-0.25 micrometers.

9. A method for preparing composite short fibers for air filters, characterized in that, Includes the following steps: Using a masterbatch injection device, an antibacterial masterbatch containing antibacterial material is melted and injected into the melt of the first polymer to form a high-melting-point B-component fiber-forming polymer melt; after melting the second polymer, a low-melting-point A-component fiber-forming polymer melt is obtained. The high-melting-point B-component fiber-forming polymer melt and the low-melting-point A-component fiber-forming polymer melt are respectively injected into the apparatus for manufacturing composite short fibers for air filters as described in claim 7, and the composite spinning process is used to obtain the composite short fibers for air filters.

10. The method for preparing composite short fibers for air filters according to claim 9, characterized in that, The method for preparing the antibacterial masterbatch containing antibacterial materials includes: blending, melting, and kneading antibacterial material powder with a first polymer at a weight ratio of 1 to 4:10 to prepare antibacterial masterbatch; Preferably, the antibacterial masterbatch is dried in a vacuum drum until the moisture content is below 50 ppm, and then the antibacterial melt is injected into the high-melting-point fiber-forming polymer melt of component B using a masterbatch injection device.

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